THE ERYOZOA 0F MSCHKBAN TAXQNOPMY. ECGLQGY AM? blSTRSBUTIGN WAR? II mcwm, maximum mu LONGEB'ITY. cu: WBREW {PART H} Thesis for fhe Dom-M 06 Ph. D. MlCHEGAN SKATE UNIVERSE‘W Rmhn Mama Bushnail, Jr. 1.9251 This is to certify that the thesis entitled THE BRYOZOA 0F KICHI GAN TAXONOMY, ECOLOGY, AND DISTRIBUTION (PART I) GROWTH, MORTALITY, AND LONGEVITY or PLUMATELLA REPENS (PART II) presenteflg John Horace Bushnell, Jr. has been accepted towards fulfillment of the requirements for P111 D: degree in ZOOIOEY Maj professor 0-169 LIBRARY Michigan Sta I: University THE BRYOZOA OF MICHIGAN TAXONOMY, ECOLOGY} AND DISTRIBUTION (PART I) GROWTH, MORTALITY, AND LONGEVITY OF PLUMATELLA REPENS (PART II) BY John Horace Bushnell, Jr. AN ABSTRACT OF A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Zoology 1961 ABSTRACT THE BRYOZOA OP ICICILIGAII TAXCIICLY, ECOLOGY, AND DISTRIUJTIOI: (PART I) GROWTH, MORTALITY, AND LONGEVITY OF PLUMATELLQ REPENS (PART II) by John Horace Bushnell, Jr. The purpose of this investigation was twofold: first to amplify distributional, ecological, and systematic know- ledge of Michigan Bryozoa, and second, to obtain growth, mortality, and longevity data on Elemetellg repens. No extensive experimental study had previously been conducted, to obtain growth, mortality, or longevity data on fresh-water Bryozoa living in natural habitats. This portion of the study was accordingly conducted in the field. Collections were obtained from 122 bodies of water in Michigan. Three species not previously reported in hichigan were found: Plumatella fruticosa (10 sites), Lgphopodellg carteri, and Stolelle eyelinae. Plumatella grbispermg, found previously only by Kellicott (1882), was discovered in three ponds. This form is more fully described and assigned to the genus Eyelinella. The new designation is_§yalinella orbisperma (Kellicott) 1882. Flabelliform and geminate-flabelliform colonies of Plumatella emarginata were found. Evidence is presented to demonstrate that this growth form may sometimes be the result of a simultaneous germination (with a subsequent loss of the valves) of two contiguous statoblasts. A discussion on the systematics of the species collected in Michigan, and on their relationship with.world-wide forms, is presented. John Bushnell The growth data suggest that the increase in the number of polypides in colonies of‘g. repens tends to be geometric. This tendency is most clearly revealed by colonies growing under favorable conditions. Healthy colonies at favorable sites doubled in size each 3.4 to 7.4 days. The summer doubling time was 3.4 to 4.9 days, and the spring doubling-time was 4.0 to 7.4 days. Temperature is correlated with this difference. Erratic or depressed growth was noted at some stations, and densitybdependent and densitybindependent factors are discussed in relation to variations in growth. An extremely high attrition of.§. repens colonies was observed at some stations. Colonies of several hundred poly- pides were sometimes destroyed between two observation periods. Occasionally an entire substrate was denuded of colonies. Colonies located largely free of dense vegetation and not too close to the lake bottom were believed most successful because they were less accessible to crawling predators and to deleterious chemical factors. The importance of site and chance in relation to mortality was discussed. Longevity data for 373 polypides were obtained. ‘3. repens polypides lived from 4 to 53 days. Four ancestrulae survived for 29 to 53 days. The survivorship curve suggests that the greatest number of polypides die between 21 and 36 days. Eighty per cent of the polypides died within 28 days. Twelve of the 375 polypides survived longer than 57 days. John Bushnell Attention is concentrated on‘g. repens and‘g. emarginate. A variant form, classified under.§. emar inata, was found at six localities. It has characteristics consistently intermediate between‘g. repens and‘fi. emerginata, and also shares characters with Plumatella elegans and glumatella javanica. Fredericella sultana appeared to be the species most tolerant of marly habitats. '2. repens was found to be a lake, pond, and ditch form, mndlfi. emarginata demonstrated a decided preference for streams. New tolerance limits for temperature are presented, namely; 1.5 degrees centigrade for‘g. sultana, and 37 degrees centigrade for'fi. regens and'g. fruticosa. 2, fruticosa was found in water with the greatest color and the lowest pH. Lists of plants and animals found in association with Bryozoa are given, and a discussion of bryozoan-sponge and intra-bryozoan associations is presented. Bryozoan predators included Gastropoda, Tendipedidae, Elmidae, and fish. However, Trichoptera were the most frequent predators. In particular, Athripsodegggg. and Orthotrichig‘gp. were seen repeatedly attacking and eating polypides (and statoblasts) of g. repens. Growth, mortality, and longevity data were obtained by inserting plastic page of different colors into substrates, beside colonies or polypides. Where possible, colonies recently derived from statoblasts were chosen for study. Parallel studies were conducted at several stations on two small Michigan lakes, both of them.water-fow1 sanctuaries. Copyright by JOHN HORACE BUSHNELL, JR. 1962 THE BRYOZOA OF MICHIGAN TAXONOMY, ECOLOGY, AND DISTRIBUTION (PART I) GROWTH, MORTALITY, AND LONGEVITY OF PLUMATELLA REPENS (PART II) By John Horace Bushnell, Jr. A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Zoology 1961 "J 1".' , :l '. -’ 1’ L,‘ ,. (9/7. CE} .2 ACKNOWLEDGEMENTS My appreciation and respect are directed first to Dr. T. W. Porter whose enthusiasm helped to ignite my interest in aquatic creatures. His direction, assistance, and criti- cism, through all phases of this research, were immediate and meaningful. Gratitude is extended to Dr. G. J. Wallace, Dr. L. W. Mericle, Dr. wm. B. Drew, Dr. M. M. Hensley, Dr. G. W. Pres- cott, and Dr. P. J. Clark who have all contributed to my. education and the guidance of this research. Their patience, time, and wise counsel have served to ripen my biological perspective. Further appreciation is accorded to Dr. P. J. Clark for his suggestions with respect to the handling of quantitative data. ‘ My investigations were aided by the use of the facilities of the W. K. Kellogg Biological Station of Michigan State 'University; by the cooperation of Hr. R. D. Van Dousen, Director of the W. K. Kellogg Bird Sanctuary on Wintergreen lake; by the assistance from a grant held by Dr. T. W. Porter, and by the services and facilities made available to me by washington and Jefferson College, in particular, by us. W. R. MbWhinney, reference librarian. Certain identifications and confirmations of Protozoa and algae were made by Dr. J. O. Corliss of the University of Illinois and Dr. G. W. Prescott, respectively. Helpful suggestions and opinions were given by Dr. Mary D. Rogick of New Rochelle College, New Rochelle, New Ybrk; ii iii much.valuable literature was received from Dr. M. Toriumi of the Biological Institute, Tohoku University, Sendai, Japan, and from Dr. H. Marcus of the University of Sao Paulo, Brazil. To each of these people, I am sincerely grateful. I am in addition, appreciative of the photographic assistance given by Mr. 8. Arthur Reed and of the numerous and efficient services rendered to me by Hrs. Bernadette Henderson. Finally, my affection and.gratitude are expressed to my wife, Judith. Her assistance has been continuous, her determination tireless, and her encouragement gentle. She has served clerically, artistically, and editorially. Her endeavors were indeed an expression of devotion , and I shall not forget them. TABLE OF CONTENTS Page PART I INTRODUCTION 1 METHODS AND'MNTERIALS 5 Temperature Data .5 Chemical Data 5 Collections and Study 5 Narcotization and Preservation 6 measurements and Study 8 Illustrations 9 COLLECTION DRTA ll TAXONOMICAL DISCUSSION 21 Cristatella mucedo 21 Lophopodella carteri 23 Fredericella sultana 27 Paludicella articulate 31 Plumatella repens 34 Plumatella emarginata 47 Plumatella emarginata, Pony Creek form. 63 Plumatella fruticogg 72 ‘Hyglinella orbisperma - new designation 81 Diagnostic Revision,'§. orbisperma 94 'Hyglinelle gunctata 95 Stolella indica 99 Stolellg evelinae 103 Unidentified Specimen 109 iv ECOLOGICAL DISCUSSION Physical Factors Bottom composition Current and water movement Temperature Chemical Factors Biological Associations Botanical Zoological Predation SUMMER! PART II INTRODUCTION Wintergreen Lake Burke Lake METHODS Marking Random choice Checking colonies RESULTS Growth Mortality Longevity GROWTH DISCUSSION MORTALITY'DISCUSSION LONGEVITY’DISCUSSION Page 111 112 112 114 118 120 121 121 131 144 149 151 152 154 156 156 167 168 172 172 175 175 176 189 193 vi Page SUMMARY 196 APPENDIX 198 LITERATURE C ITED 2 98 TABLE 1. 5. 4. 5. 6. 7. 8. 9. 10. 1‘37 0 38‘42 e 45. LIST OF TABLES ‘Distribution records of Bryozoa collected in Michigan.between 1957 and 1960 Plumatella reggae measurements Plumatella emarginata measurements Plumatelle fruticosa measurements . ‘Hyelinella orbisperma and‘gyglinella punctata measurements Plants found in association with Bryosoa Animals found in association.with Bryosoa Showing the frequency of association of the species of Michigan Ectoprocta collected General data for each study station at Burke Lake, Clinton County General data for each study station at Wintergreen Lake,‘Ka1amazoo County APPENDIX TABLES Growth data Longevity data water temperatures taken at Wintergreen Lake and Burke Lake on the date when data were collected. vii Page 16 42 53 79 86 122 133 142 157 158 263 292 297 Figure l. 5. 4. 5. 6. 7-10. 11. 12. 15. 14. 15. 16. 17. 18. 19-20 a 21. LIST OF FIGURES Distribution map showing the species of Ectoprocta found in Michigan Colony of Lophopodella carteri Statoblast of Lophopodella carteri Enlarged statoblast of Lgphopodella carteri Sessdblast of Fredericella sultana Septum of Plumatella repens Plumatella repens floatoblast, dorsal side Plumatella repens defective floatdblast Plumatella repens sessoblast Plumatella repens sessoblast showing reticulations Plumatella emarginate zooecium Plumatellg emarginata floatoblast, dorsal surface Plumatelle emarginata floatoblast, ventral surface Plumatella emarginata, flabellate and geminate flabelliform colonies Showing a colony intermediate between the f1abellum.and Jugalis forms Plumatella emarginata (Pony Creek form) floatoblast, dorsal surface Plumatella emarginata (Pony Creek form) enlarged floatoblast, dorsal surface viii Page 14 25 25 25 30 45 45 45 45 45 58 58 58 61 61 67 67 22. 23. 24. 25. 26-270 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. ix Plumatella emarginata (Pony Creek form) enlarged portion of a floatoblast, ventral surface Plumatella fruticosa zooecium showing special budding zone Serrated zooecium of Plumatella fruticosa Plumatella fruticose floatoblast, dorsal surface Plumatella fruticosa sessdblast Plumatella fruticoeg enlarged sessoblast Colony of Hglinella orbisperma, Barry County Colony of Eyelinella orbisperma, Iosco County Elongated zooecium of‘Hyelinella orbisperma igyalinella orbisperma statoblast, dorsal surface Igyalinella orbispermg enlarged statoblast Linear colony of‘Hyglinellgflpgnctata Hyalinella punctata statdblast, dorsal surface Stolella indica colony Stolella eyelinae colony Stolella eyelinae colony jgtolellaigzelinae statoblast, dorsal surface 67 75 75 80 80 80 82 88 88 98 98 100 108 108 108 Figure 40. 41. 42. 43. 44. 45. 46. 47-48 0 49-500 51-53 0 54-55. 56. 1 -28. 29 -36. 37. Stolella evelinae statoblast, ventral surface Showing release of a statoblast by a living pOlypide of Stolella evelinae Dense tufts of Fredericella sultana A pond, Barry'County, where‘Hyalinella orbisperma was collected Hall Lake, Barry County, where Peeli- natella magnifies was found Colony of Fredericella sultana attached to dorsum of an Odonata larva Trichopteran case composed largely of Lophgpodella carteri statoblasts Study stations at Burke Lake, Clinton Co. Study stations at Birke Lake, Clinton Co. Study stations at Wintergreen Lake, Kalamazoo Co. Plumatella repens growth study colonies designated by colored plastic pegs Miniature grid divided into one cm. squares used in counting dense bryozoan colonies APPENDIX FIGURES Growth graphs Gross mortality graphs Survivorship curve for 373 polypides of Pigmetella repens Page 108 108 115 117 117 145 145 160 161 162-163 166 170 198-252 253-260 261 ART I TAXOIT HY, ECOLOGY, AND DISTR BU'I‘ION INTROIIICTION The taxonomy of the fresh-water Bryozoa has been a subject of frequent disagreement.among Bryozoologists. This disagree- ment has been particularly evident with respect to the family Plumatellidae. The separation of genera and species within the Plumatellidae has frequently been a challenge to the_ resourcefulness of systematists. Categories higher than.the family, as Hyman (1959) has stated, do not appear Justified, or too useful, because of the structural similarities exis- ting among all the phylactolaematous Bryozoa. Several classification systems have been erected for the fresh-water Bryozoa, the most notable of which have been those of.A11man (1856), Jullien (1885), Kraepelin (1887), Vangel (1894), Rogick (1935a), and Toriumi (1956b).. The last is a correlative study based upon Toriumi's earlier series of taxonomic studies numbered I through XVI. Other notable contributors to the problem of fresh-water bryozoan clas- sification have been Braem (1890) and Rosenberg-Land (1896). Hewever, the classifications of Allman and.Kraepelin have been most frequently'used‘by investigators in the past. . Toriumi's recent studies are the most definitive undertaken in this century and serve to illuminate and clarify several of the taxonomic problems which have made fresh-water bryozoan classification so difficult. His studies are of particular merit, because he has suggested taxonomic characteristics of fresh-water formm,heretofore neglected by other workers. He has also methodically investigated certain of the more per- -1— -2- plexing aspects of classification (e.g., variations in the incrustation of the ectocyst, variations in colony growth form, and variations in the wrinkling or lamellations of the zooecia). He has found many of these variations to be highly intra-specific. His work thus cautions against a reliance upon certain criteria formerly used to determine species. Much of Toriumi's information has been obtained by growing young colonies in the laboratory. In addition, he has placed certain species in synonymy, and he has reinstated certain of Allman's (1856) species (e.g., Plumatella emarginata and Plumatella fruticosa). Several workers have given a number of variety designations to species of Bryozoa. Kraepelin (1887) uti- lized variety designations freely. Certain of his varieties had species status in Allman's classification (e.g., Allman's Plumatella repgns became Plumatella polymorpha var. repgns inJKraepelin's systematics). All forms which are today generally recognized as belonging in the genus Plumatella, Kraepelin placed in two species: princeps and polygprpha. Other workers have used the variety designations. Here recently Rogick (1935a) placed all forms of Plumatella occurring in America, in the species repens, as varieties. She elevated some of these varieties to species status in 233313 M11 Biology (Edmondson revision, 1959). Toriumi, in the past - decade, has refrained from using the variety designation in classification. Marcus (1942) and Harcus (1946; 1955) have uti- lized the form.and subspecies designations. As Cain (1954) -3- states, the variety designation has been largely abandoned because of its all inclusive implications. It has been used with.reference to seasonal forms, genetic variants, and rep- resentatives of morphologically and geographically distinct populations. The subspecies, the criteria for which rest upon the quantitatively demonstrable taxonomic characteristics existing within distinct geographical populations, has received little application. A historical study of the intra-generic categories of the Plumatellidae suggest that this family may contain polytypic species, as defined by the new systematics. Michigan is one of a relatively few states in which several bryozoan collections have been made. Brown (1933) collected from some 50 sites. However, nearly all of these collections were made in three counties as his study was concerned primarily with a non-systematic study of statoblasts. .Rogick and Van der Schalie (1950) summarize and augment the collection records and descriptions for the state. Brown's investigation includes some ecological data, and more information is given in other papers published throughout the world. Certain of the more important of these reports have been written Allman (1856), Davenport (1904), Harmer (1915), Harcus (1926, 1934), and Hurrell (1927). Biological information on the fresh-water Bryozoa is fragmentary. Bryo- zoan-plant associations have been reported by several investi- gators. However, few reports include algal associations. Several investigators have recorded animal associations with freshpwater Bryozoa. Predators of Bryozoa have been reported by Harcus (1926, 1954) and a few others. I have talked to -4- several biologists who have expressed an interest in bryozoan- sponge associations. Several scattered records have been published. From the review of the literature and through preliminary collecting of Bryozoa, I came to appreciate the perplexing nature of bryozoan systematics. The present study was con- ducted in order to amplify the distributional, ecological, and systematic knowledge of Michigmn Bryozoa. Particular attention is given, in both sections of this dissertation, to the family Plumatellidae. METHODS AND MATERIALS Temperature Data Temperature readings were taken with a standard 0 to 100 degree centigrade field thermometer. Chemical‘gggg A set of sealed standard color tubes manufactured by ' 'LaMotte Chemical Products Company was used to obtain pH read- ings. Second readings were sometimes taken with a Beckman ' electric pH meter, particularly at sites where the water was colored or murky with suspension. Alkalinity data were gathered by the standard method employing methyl orange and phenolphthalein as color indica- tors and titrating with N/50 hydrochloric acid. Standard laboratory glass-stoppered reagent bottles were used to col- lect water samples from various stations. Analyses were made immediately at the collection site either on shore or in a boat. Alkalinity readings were not made on water which had been in collection bottles for longer than 45 to 60 minutes. Collections‘egg‘ggggy Bryozoan collections for this study were made over a period of four years, beginning with the summer of 1957 and ending during the summer of 1960. Most of the collections were made from a boat or while walking in shallow water. Occasionally colonies were Obtained by diving for them, or by throwing out or towing a standard plant hock from a boat. Collections were obtained from substrates located over organic, marly, and sandy bottoms. They were obtained from lotic and lentic -5— -6- habitats and from wave-washed shores. In collecting from the littoral area of a lake or in making collections at any specific site on a body of water, stones, sticks, logs, and other likely substrates were examined. The leaves and stems of numerous plants were examined. When algae or animals were present on substrates in close association with Bryozoa, specimens were removed for identification. Numerous animals and plants were identified to genus and species when in particularly close association with Bryozoa. Some identifications were made in the field with the aid of 10X, 15X, and 20X hand lenses. If bryozoan colonies were attached to plants, the portion of the plant to which the colonies were attached was removed. If the colonies were growing on a wood substrate, a piece of wood' holding the colonies was removed with a scalpel or knife. Many colonies were growing on stones or rocks. Small stones were collected. Colonies were carefully scraped from the surface of larger rocks or stones. .Living colonies were kept in finger bowls and petri dishes until tentacle counts and other Observations could be made. Many hours were spent in observing colonies in the laboratory. Narcotization and Preservation Careful narcotization is necessary in order to preserve Bryozoa in a fully evaginated and life-like state for pur- poses of further study. Narcotization is variously accom- plished. Chloral hydrate, menthol crystals, cocaine, and chloretone have been used. The author has found chloral hydrate less effective than menthol as an anesthesia. How- ever, a combination of chloral hydrate and menthol has -7- generally proved very satisfactory. The procedure, when using both substances, was to place the colonies in a one per cent aqueous chloral hydrate solution (in a small stender or petri dish) for 15 minutes. Two medicine droppers full of saturated menthol solution were added every 10 to 15 minutes. Within one or one and one-half hours, the colonies were usually sufficiently insensitive to be placed in a fixative or to be preserved without fixation. Narcotization was successful if several polypides from different parts of the colony failed to retract when tapped rather forcibly on their tentacles and zooecial tips with a small dissecting needle. Experimentation proved that narcotization was not achieved equally well by a single method. Lophopodella carteri, Pectinatella magnifica, and Plumatella repens were generally preserved in a well evaginated state by the method outlined above. Fredericella sultana, Paludicella articulata, Plumatella emarginata, and other Plumatellidae were effectively narcotized using a saturated solution of menthol. This solution was pipetted (two droppers full every 10 to 15 minutes) into small stenders or petri dishes containing the Bryozoa and water from their collection site. The effectiveness of the chemical was judged by the amount of it required for narcotization, by the number of polypides which remained evaginated after preservative was added, and by the completeness of evagination. When effec- tively accomplished, nearly every polypide remained evaginated and appeared to be maximally extended. Elglinella orbigperma was most often refractory to chloral hydrate or menthol -8- anesthetization. These chemicals were used on several occasions with poor results. Then a saturated solution of chloretone was administered (in the manner described for using a saturated menthol solution), and excellent results were Obtained eech time. Following narcotization, colonies were preserved in 70 per cent alcohol or in 4 per cent formalin. On occasion Bouins fixative solution was used followed by alcohol or for- malin for permanent storage. Formalin is perhaps better for gelatinous colonies as it gives some added stiffness to the soft ectocysts. Collections made during the last year were often preserved in sugar-formalin solutions. This combination is one suggested by Jackson (1919), a medical doctor, and has received little subsequent comment from investigators. This preservative is recommended, particularly for gelatinous colonies. Colonies remain swollen and the delicate tentacles remain straight and expanded. Osmosis and the density of the solution perhaps help to promote the condition. Certain vari- ations of the original formula were found most effective. The following ratio was preferred: Cane sugar 12 parts Formalin 5 parts Distilled water 100 parts Jackson employed the sugar-formalin combination successfully for the preservation of insect larvae and pupae. Measurements 9.9.9. S3391 _Mbst study and measurements of living and dead colonies were made with a Bausch and Lamb dissecting microscope. ,The ..9— ocular micrometer was calibrated against a stage micrometer. A Bausch and Lamb compound microscope equipped with an ocular micrometer was used for additional observation and measurement. Tentacles were often difficult to count and several counts were sometimes necessary. Four to 10 tentacle counts were taken on each living colony. Newly budded individuals were avoided as they have fewer tentacles, in most species, than older polypides.l On extended field trips tentacle counts were made with a binocular dissecting scope. Dissections of the zooecial tubes were facilitated by watch makers forceps and insect minuten needles. Illustrations Most of the illustrations used are photographs. Habitat photographs were obtained in the field with an Argus C-4 camera. The underwater photographs of Fredericella sultana colonies were made with the aid of a square wooden box, three feet long, which was open at the camera end and sealed with a glass plate at the underwater end. The sealed and was submerged to within a few inches above the colonies to be photographed. Photomicrography was accomplished with.a.Kodak "Pony" camera mounted on a late model American Optical Company compound microscope. A 10X eyepiece was used most successfully in conjunction with the following objective powers and lens speeds: 5X - 1/125 second, 10X - 1/50 second, 45X - 1/25 second. These speeds were generally effective when the vari- able light source was set at maximum.intensity. The variable backgrounds and substrates made it necessary to alter the .10... above settings occasionally. Kodak Tri-X film was used. Drawings were made with a monocular compound microscope equipped with a calibrating eyepiece. The drawings were made using graph paper placed under tracing paper so that correct measurements and proportions could be obtained. COLLECTION DATA The material for the present study was collected during the years 1957 through 1960, from 122 separate aquatic habi- tats, including lakes, rivers, creeks, ponds, and ditches, located in 48 counties in Michigan. The distribution, by counties, of the species of Ectoprocta collected in this study is shown in Fig. 1. Each of the species is indicated by a symbol. The larger symbols represent species found during the present study with the exception of those recorded by Dr. T. W. Porter, for Cheboygan and Alger Counties. The small symbols represent reports made by other collectors. Only county species records which are not duplicated by the present study are represented by the small symbols. These were included so that published county records for the state would be as nearly complete as possible. The reports indi- cated by small symbols were obtained from the Rogick and Van, der Schalie (1950) publication on Michigan Bryozoa. A list of the collection sites visited during this study is given in Table 1. Three species not previously reported for Michigan were collected during this investigation. These species are Plumatella fruticosa, Stolella evelinae, and Lgphopodella carteri. Specimens collected near Ann Arbor by Kenk (1949) were identified by Dr. M. D. Rogick as Stolella indica. They were somewhat atypical and in Fresh Water Biology (Edmondson revision, 1959). The only occurrence record given is from Pennsylvania. Stolella indica was collected during this study, '11- .12- and on the basis of Kenk's report must be assumed to be the second record for the state. A species described by Kellicott (1882) as Plumatella orbisperma was found during this study. Prior to the present.investigation, this form had been found only by Kellicott, in a pond near Little Traverse Bay. I have transferred this species into the genus_Hyalinella. The flabellum form of Plumatella emarginata and the fungosa form of Plumatella repens are also recorded for the first time in Michigan. The Bryozoa with the greatest number of occurrences show no pattern in their distribution. They were present in collections from all parts of the state. ’Pectinatella maggifica has occurred more frequently in the southwestern portion of Michigan. The record for Mackinac County is tentative because only statoblasts of this species were found on rocks in a protected bay on Lake Michigan. These may have been carried by wind or current from the southern portion of the lake. Eight of the ten collections of Plumatella fruticOsa made during this investigation, are recorded from the northern half of the state (north of a line formed by the westward extension of the southern border of Iosco County), and three of these occurrences were from the Upper Penninsula. The uneveness of this distribution may be even greater, since more collecting was done in the southern part of the state. Plumatella casmiana was not found during this investigation. However, the collection records for this species are indicated -15 _ on the distribution map, Fig. l. The entoproct, Urnatella gracilis, is not included on the distribution map, but it has been recorded from the Grand River in Ionia County, by Rogick and Van der Schalie (1950). .44- Fig.1 . Distribution. map showing The spec) es of Eciopmcla. found in Michqun Cjisloiella, muceglg Freder i cell at Sullcmd Eyelinello. Punc‘ioio- Stolella mound;- Plumatella, [ems l:l_ allnello. orblspermo. Plumatella emargmaia Eggshepoclello. carteri ‘ Pecilhd’tella, maqflfg Plumaiello, -‘Prullcosa. Paludicella. articulate. Stolella indica. A PLthaieLla, CaSmldno. RFD'GOOOBID U Lox er s mbols represent ColLecl’lons made Cluxlh ’the present Stud . A number follow/m 0t Symbol mild-01635 ‘the number of different locolltles from which +he Species was collected m the Connie. Small-er Simbols. Yepresen‘l Collections mode b\l prevlcus anCSILfiCLIOYS- F: .1. 00 O an M 000. 1 OTC l 00A I I . 5 L ‘ D 00 n O . NB , CODA l'l AU 0.0 a s 3 2. 00.0 COD 7 00 u. . 3. AOL . . . r 7 a . 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The colonies are among the most easily identified of the fresh- water Bryozoa. Colonies as long as 35 cm. and 50 cm. were observed on the stems of Nuphar advena on Wintergreen Lake. Tentacles The number of tentacles counted on 84 polypides varies between 78 and 96, averaging 85. This number is consistant with the average of 80 given by Allman (1856) and later investigators. Statoblasts Fortybone measured statoblasts average 1.02 mm. in diameter thus falling well within the range given by previous investi- gators, more recently by Toriumi (1943). Kraepelin (1887) distinguishes two varieties, i323 and genuina, on the basis of the statoblast size and number of spines. However the sizes and spine numbers of the Michigan Cristatella mucedo statoblasts overlap Kraepelin's figures. The spine numbers on the dorsal face varied between 50 and 42,-while there was a variance of between 15 and 30 on the ventral face. Toriumi (1943) has indicated that Japanese collections reveal inter- mediate sizes and numbers of spines, and he suggests that seasonal and local factors are responsible for this overlap. Accessory hooks were noted on several statoblasts from -21.. _22” Wintergreen Lake, Kalamazoo County. Hodk variations are discussed by Toriumi. Pectinatella magnifica Leidy 1851 Colony The colony is typical of that described by Leidy (1851b,c). Older colonies are massive with secondary colonies seen as rosettes, a single layer in thickness, covering the surface of a large central gelatinous matrix. Leidy mentions the dark rose-red color of the margin of the inner tentacles and mouth region. Young colonies collected at Hall Lake in Barry County and Sunset Lake in Kalamazoo County revealed this same characteris- tic. However, the author has also noted this coloration for Plumatella emarginata and believes this characteristic is variable and thus should not be considered specific. The largest and most abundant colonies of Pectinatella magnifica were seen in the St. Joseph River, St. Joseph County, and in Hall Lake, Barry County. Rogick and Van der Schalie (1950) record that Dolley collected‘g. magnifica from the St. Joseph River. Two colonies seen in the present study had diameters of slightly over 10 and 12 inches. Borodin (1928) records that‘g. magnifica colonies attain the size of a man's head, and he reports one colony with a diameter of 8 by 5 inches. However, Geiser (1957) states that observers have asserted that colonies of 24 inches were not rare in overflow pools in Iowa. He estimates that during the months of July and August in one year "scores of thousands" of tons of Pectinatella passed over a dam. Judd (1950) records a -23... colony with a diameter of 11 by 14 inches from a marsh near . Hamilton, Ontario. Tentacles ' Of 147 polypides, tentacles numbered 62 to 85 with 90 per cent of the polypides having between 70 and 84. Leidy (18511») gives the tentacle number as between 50 and 80. Davenport (1904) states that tentacles range from 60 to 84. Statoblasts Diameters ranged between 0.84 mm. and 1.1 mm. on 48 measured statoblasts. Hooks numbered 12 to 22, with an average of 16. This agrees well with the 14 to 16 spines Leidy (18516 reports and the 11 to 22 range reported by Davenport (1904). There is some variability in the morphology of the hooks of statoblasts. This has been discussed in detail by Davenport (1900). Pectinatella magnifica is perhaps the easiest of the fresh-water bryozoans to identify as taxonomic characters are distinct and reliable. macroscopically, young colonies may sometimes be confused with young Cristatella colonies. Lgphopodella carteri (Hyatt) 1865 The collections from Wintergreen Lake, Kalamazoo County, are the first record of this bryozoan in Michigan, and one of the few reports for the Western hemisphere. The species was first reported by Rogick (1934) from Lake Erie. Statoblasts of this species found in bottom samples were given to the author for identification by Mr. Rudolf Scheibner in March of 1957. The colonies were abundant in all parts of the lake -24- from 1957 through 1960. Colony The colonies are typically globular and gelatinous ranging in form from somewhat round to elongated (Fig. 2). The colony, with proliferation, becomes lobate with from six to 10 or 12 individuals in each lobe. Colonies may break up into daughter colonies. Takahasi (1934) reports colonies that had from 20 to 45 polypides. The Wintergreen Lake colonies were commonly composed of 35 to 55 polypides, and one colony was found with 70 polypides. The polypides range in length, from the anus to the tip of the stomach, 1.08 mm. to 1.52 mm. Lophopodella colonies are motile, moving up to 10 to 12 cm. per day (Dahlgren 1934). Ectocyst The ectocyst has a medium, stiff, gelatinous consistency and lacks incrustatibn. It is hyaline, often appearing some- what yellowish in color. It is non-sclerotized, and the surface of the ectocyst was observed to be finely papillose. Vorstman (1928a) states that the external surface of the polypides collected from Java are covered with minute tubercles. Zooecia Polypides are contiguously situated, withdrawing into a common cavity. As Toriumi (1956a) states, "Only the tip is recognizable as the remnant of each zooecium." The zooecial diameter in the distal region averages 0.5 mm. This figure is in agreement with Rogick's (1934) average of 0.544 mm. 3. swim” — (lei-waned Spines “0" clear) Ffa‘. Sick Oblfls“ - enLcu ement Showi {but cetis and +evmiv'u‘2l spiues uni-k barbs. F; a 4. -26.. 422322 Septa are not present. Tentacles The tentacles of non-ancestrulae vary in number from 67 to 89 in the Wintergreen Lake collections.' The average number was 79 tentacles (145 counts). These figures are in nearly perfect agreement with Toriumi (1956a), who gives the range in the Japanese forms as 68 to 91 tentacles with a central range of 78.5 to 80.8. These figures are higher however, than those given by Rogick (1934) for Lake Erie collections. She. states the tentacles varied in number from 52 to 82 with a median number of 64. Several investigators, including the author, have noted environmentally associated variations in tentacle numbers. Statoblasts The spinoblasts are saddle-shaped (Fig. 3), varying some- what in form. The length varies between 0.9 mm. and 1.14 mm. on 53 measured statoblasts (exclusive of spines), with an average of 0.91 mm. The width varies from 0.67 mm. to 0.85 mm. These figures, as well as those on float coverage, cap- sule length and width, .3... perfectly with those of Toriumi and Rogick. The terminal spines vary in number between 7 and 18 with the average between 10 or 11. The number of recurved barbs on the margin of each spine varies from 2 to 21 with the average falling between 12 and 13. Rogick (1936) states that the average number of barbs along the spine margins of her collections was 11.2, with a maximum.of 22. Lee (1936) ._.2 7... reports a rather low number of barbs, two to nine for each spine. All of the measurements for the Wintergreen Lake specimens are essentially in agreement with those of Rogick. Variations were noted in the relative development of the spines and barbs. Some of the spines are diminutive or slightly imperfect. The terminal ornamentation of a'Lgph_- podella carteri spinoblast is shown in Fig. 4. One of the spines has 19 barbs. Statoblasts were observed in the process of forming in a colony of 12 individuals. The statoblast from.which the colony had germinated was still attached. Fredericella sultana (Blumenbach) 1779 Fredericella sultana is second only to Plumatella repens in abundance in the Michigan collections. This was not unex- pected as the species is one of the most frequent and cosmo- politan fresh-water Bryozoa in the world. Colony - The colonies from Michigan habitats vary from small and largely repent with.widely open branching, to colonies often largely free of the substrate. It was not uncommon to find this form growing in dense tufts, from the underside of logs, or on fine protruding rootlets on the lake bottom or in the sand. Such dense colonies were abundant in the outlet to Gull Lake inJKalamazoo County and in Margreth Lake in Crawford County. The branching is typically antler-like and open. The lophophore is actually of horse-shoe shape when retracted, as Toriumi (1951) has observed. It usually appears circular when the polypide is extended. -23- Zooecia The zooecia tend to be elongated and are often vertical to the substrate. A distinct keel is present on repent zooecia while the keel in the free zooecia is sometimes obscure or lacking. The development of the keel in the Michigan specimens is variable, in agreement with Toriumi. The zooecial tips are sometimes smooth, or lamellated. The serrated branches, discussed by Toriumi, were not seen. The width of the zooecia, which tapers little from the proximal to the distal ends varies in measured specimens between 0.17 mm. and 0.33 mm. Rogick (1940) gives diameter measurements of 0.16 mm. to 0.35 mm. for New Rochelle and Lake Erie specimens, with an average of 0.24 mm. The only other United States form, Fredericella australiensis browni (Rogick 1945b) has tubes varying from 0.259 and 0.576 mm. in width. Dendy (1906) reports on an extremely slender form of Fredericella sultana from New Zealand. Ectocyst The ectocyst is sandy-brown, greyish, or grey-white in color. It is most often moderately to heavily incrusted. Toriumi (1951) investigated the color and incrustation of the ectocyst and found no field specimens to be colorless and transparent. However, laboratory-reared specimens had nearly hyaline ectocysts. Essentially hyaline and transparent speci- mens were collected from five lakes in Michigan. These are the first field specimens of‘E. sultana with these charac- teristics. Marcus (1946) describes a subspecies, Fredericella -29- sultana crenulata, in which incrustation with diatoms is always slight. Fredericella australiensis trancaucasica (Abricoaoff 1927a) is also a form with light incrustation. The zooecia are essentially hyaline, transparent, and lacking incrustation on specimens from Round, Mbcosta, and Blue Lakes in mecosta County; Dickenson Lake in Chippewa County; and Long Lake in Grand Traverse County. The Mecosta County lakes are connected. In specimens from Crotche Lake, oakland County, and Little Manistique River, Schoolcraft County, the zooecia are transparent and only faintly yellow. In all other characteristics these colonies are typically Fredericella sultana. These observations and Toriumi's rearing experiments are correlative evidence that variability in incrustation is environmentally related and should be used with caution in systematics. manyvz. sultana specimens are heavily incrusted, of which the Gull Lake colonies are representative. These colonies are greybwhite in color. 121222 Allman (1856) states that a more or less perfect septum is frequently found at the origin of the branches, while Toriumi (1942, 1951) declares that a septum is rarely present at the origin of each branch. Kraepelin (1887) reports that he observed septa primarily at the location of main branches. The presence of the septum is variable in the Michigan zooecia, ranging from infrequent to present in nearly every zooecium. Tentacles The tentacles, counted on 283 individuals, varied from 19 to 25. The average was 22.2. This is consistent with figures -30- given by numerous investigators. Marcus (1946), however, gives the number for var. crenulata as 22 to 28. Goddard (1909) describes Fredericella australiensis with 28 to 30 tentacles. Statoblasts Only sessoblasts are found in this species. They are, characteristically, been or kidney-shaped (Fig. 5). The oval type sessoblasts of E. australiensis were not found. The sessoblasts varied in length and width (141 measurements) from 0.31 mm. to 0.52 mm. by 0.18 mm. to 0.31 mm., thus Fig. 5. Sessoblast of Fredericella sultana corresponding very closely with those of Kraepelin (1887), Rogick's (1940) New Rochelle specimens, and Harmer (1913). The reticulations on the capsule are obscure to reasonably clear. Toriumi (1951) states that the Japanese specimens tend to have a somewhat indistinct reticulation. Most frequently a single statoblast for each zooecium has been considered usual in E. sultana. Borg (l936d records one or two as common; Rogick (1940) shows a zooecium with two sessoblasts, and Marcus (1946) states that as many as six may be observed in sequence in E. sultana var. crenulata from South America. Borg reports that two or three statoblasts in a row were sometimes found in ._31_ a specimen which was possibly 2. sultana, and in one case, five were found. In several of the Michigan collections, two sessoblasts occurred commonly in each zooecium. In specimens from a pond in montmorency County, and from Bass Lake, Oscoda County, several zooecia with three sessoblasts in sequence were noted. A ciliated larva was noted in a finger bowl containing specimens of E. sultana collected in early September from Little Brevoort Lake, machinac County. Larvae have been’ found most often by other investigators in the spring and early summer. wesenberg-Lund (1907) suggests, from his obser- vations, that sexual reproduction may decline or cease in habitats progressively more northern in location. Paludicella articulata (Ehrenberg) 1831 Colony This species of Gymnolaemata is widely distributed in North.America and Europe. Rogick (1940) states that it was scarce in New York collections. However Rogick and Van der Schalie (1950) state that it was the most abundant species in collections from'the Grand River and Pigeon Creek (near Flint) in Michigan and from Lake Erie, and the Tippecanoe River in Indiana. The present study reveals that in addition to abundance and a wide distribution, this is one of the most commonly encountered species (third highest number of occur- rences in Michigan). This diminutive species may be easily overlooked or dismissed as thick algal filaments. Dr. G. W. Prescott gave the author kodachrome slides taken of an empty -32.... coenecium of Paludicella articulata, which had been sent him by a New York collector for identification as a possible new species of alga. The Michigan specimens are often luxuriant. The colonies are repent but in dense colonies large portions of the coenecia are free of the substrate. The zooecia are often entangled with one another. Branches form typically at right angles to the parent zooecium. Lateral buds develOp both proximally and distally on zooecia. The lophophore is circular and lacks the calyx and epistome characteristic of the Phylactolaemata. Zooecia The zooecia are spindle-shaped and have the typically squared orifice. Annandale (1916) describes a species, Paludicella enta onalis, having a pentagonal orifice. Rogick and Brown (1942) have found this species in Guatemala. . The length of the zooecia vary considerably within a colony. The length of the zooecia of muchigan specimens varies between 0.35 mm. and 1.6 mm., but most often between 0.70 mm. and l.25 mm. The width varies between 0.12 mm. at the narrowest and 0.32 mm. at the widest portions of the zooecium. Newly formed zooecia are often considerably shorter than those found in older portions of the colony. Toriumi(195?~4—), as a result of laboratory rearing experiments, maintains that the size of the zooecia is environmentally related. Ectocyst The ectocyst, on most of the specimens, lacks incrustation, but sometimes it is completely covered with diatoms, particu- -33 .- larly Amphor . The ectocyst is pale-yellow to yellow-brown in color. Tentacles Allman (1856) and Rogick (1940) state that this species has 16 tentacles. Kraepelin (1887) and Rogick and Van der Schalie (1950) state that the number of tentacles varies from 16 to 18, and Toriumi (1952a) gives the range as 15 to 18. The tentacle numbers of polypides in the Michigan specimens appear to vary more widely than others, at least others in North America. The average tentacle number is 15.7 for 164 animals, but the range is from 12 to 19. Several polypides had 15 and 14 tentacles. Prenant and Bobin in "Faune de France" (1956) give a range of 10 to 18 tentacles but this does not appear to be the generally recognized range. seats The septa are typically present at the base of each zooecium. , Hibernacula This species does not produce statoblasts, but forms hibernacula. These dormant and sclerotized buds vary con- siderably in shape. Harmer (1913) describes elongated hibernacula which form within the old zooecia. Others are external. Toriumi (1952a) states that the long clavate form is free from the substrate, and the shorter and indented form is adherent. Similar observations were made in the Michigan specimens, however the indented irregularly shaped hibernacula predominated. .54- Plumatella repens (Linnaeus) 1785 Colony Plumatella repens is the most common species in Michigan. Approximately 80 per cent of the colonies collected are open and repent. The remainder are dense, and the most luxuriant of these are fungoid in appearance. The colonies are dendritic and the branching, largely typical. Agglutination of zooecia is present in a few of the colonies. The variation within the genus Plumatella has often obscured systematic relation- ships. This had been particularly true with respect to'g. repgns. The budding rate, degree of elongation of the zooecia, and the character of the substrate are of particular impor- tance in determining the form of the colony (Toriumi 1955a). When the zooecial elongation and the budding rate are constant on a limited substratum, for example aJstick, a fungoid form may result. wesenberg-Lund (1896) observed that large "balls" of Plumatella fungosa originate nearly always from a large number of statoblasts in close proximity} As Toriumi (1955a) states, dense colonies are the result of many statoblasts germinating at the same time. During the spring of 1957, periodic observations were made on some colonies on fallen branches in Gull Lake. These observations reveal how dense or fungoid colonies may form. Examination with a hand lens, revealed that nearly all of the colonies had originated from a floatoblast or larva. In November 1957, when the last of the polypides died, the empty coenecia remained filled with floatoblasts and many adherent _35_ sessoblasts. In the spring of 1958, the coenecia were largely deteriorated, and most of the floatoblasts had been released. However, the sessoblasts germinated, many of them contiguously. Some floatoblasts caught or held on the substrate also ger- minated, and the branches of some of the colonies intermingled. This growth in 1958 produced a greater density of colonies than in 1957, and when these colonies fragmented and died, a greater number of sessoblasts, than before, remained adherent to the substrate. A late summer germination of all the early summer-produced sessoblasts, and of the floatoblasts which had remained in the vacinity, produced colonies which spread out and intermingled over areas of the substrate which had not previously been colonized. All of these new colonies now produced overwintering statoblasts. The network of linearly arranged autumn sessoblasts, in addition to some floatoblasts, then germinated in the spring of 1959. When the sessoblasts all germinated simultaneously, even the young colonies on the substrate were soon intermingling. The result was an increasingly fungoid mass. By late in the year a por- tion of two of the main fallen branches was completely covered by the colonies. Therefore, a new substrate, for example substrate "A", is first populated by colonies originating from floatoblasts and larvae, which are themselves produced by colonies on other substrates. Subsequent colonies on substrate "A" originate predominantly from sessoblasts as most floatoblasts are carried to new substrates, and larvae are believed to be -35- produced during only a brief portion of the year. Each generation of colonies in turn leaves greater areas of sub- strate covered by sessoblasts. The luxuriance of later generations is dependent upon the numbers and proximity of sessoblasts, and the sequential rapidity of their germination. High and regular predation would preclude such elaborate bryozoan growths. Collections of Plumatella repens from a woodland ditch in Saginaw County suggested another means by which colonies often attain dense and irregular growth. Wesenberg-Lund (1896) states that he, like Kraepelin, observed statoblasts of the preceding year germinating in the old zooecia. marcus (1926; Fig. 8, p. 294) has seen floatoblasts germinating while inside the mother zooecia. The author first collected the Saginaw County.§. repens colonies in late April. Numbers of polypides which had germinated from floatoblasts were seen protruding from the blunt open tips of the mother zooecia and from cracks in the mother zooecial wall. The integrity of the old coenecia had apparently been largely preserved, and the floatoblasts had been largely retained.within the coenecia. Sometimes most of the 10 to 15 floatoblasts within a single zooecium, irregularly oriented to one another, were germinating. In addition, sessoblasts in the repent portions of the colony were germinating within the zooecia. The composite colony resulting from the simultaneous germination of hundreds of contiguous floatoblasts and sessoblasts, variously oriented, is in effect a multitude of individual colonies each con- -37- tributing to the final architecture of the total colonial mass. In order for such a colonial mass to develop, old colonies must be preserved through the winter. Such preservation could be expected to occur in the case of particularly stiff and well sclerotized coenecia located where abrasive physical factors (e.g., wave action and current) are absent. Ditches and ponds illustrate such habitats. In shallow protected situations, standing water freezes in the winter thus helping to preserve the old colonies within the ice. In view of the fact that dense colonies may form, as has been described, caution must be used in attributing the presence of luxuriant growths of Bryozoa to a favorable nutrition. Zooecia ‘ f The angle at which the zooecial tips bend upward from the substrate in the Michigan specimens, varies from approximately 30 degrees to approximately 70 degrees and is usually between 40 degrees and 55 degrees. The zooecia are rounded in contour in 85 per cent to 90 per cent of the Michigan specimens. Rogick (1940) states that a slight keel is evident on certain "older and basal zooecia". Toriumd (1955a) found an obscure keel on some zooecia of several Japanese specimens. Some of these same specimens were furrowed, and he found a few zooecial tips of one specimen to be emarginata. An obscure keel is present distally on some of the older zooecia of specimens from six Michigan collection sites. An obvious keel is present on four others. Wherever an obscure or an obvious keel is present, the furrow is also -38.. seen. Emarginate zooecial tips were present on two specimens, collected from Detour Harbor, Chippewa County, and Byram.Lake, Genesee County. The zooecia of the Michigan specimens generally have a gradual taper from the distal to the proximal end. Occasional colonies have zooecia with an accentuated taper or with very little taper. The zooecial diameter of Regick's specimens is stated to be between 0.54 mm. and 0.70 mm. Her averages for each of two collection sites is 0.44 mm. and 0.52 mm. Toriumi states that the zooecial width of the Japanese collections compares favorably with that of North American and European specimens. The zooecial diameter of the Michigan specimens varies from 0.19 mm. to 0.69 mm. proximally. Each of these extreme diameters was recorded for exceptional single speci- mens. Omitting these exceptional specimens, the proximal diameters vary from 0.27 mm. to 0.59 mm. The distal diameters vary from 0.32 mm. to 0.88 mm. The extreme measurements overlap Rogick's maximm and minimm figures, but this is not unexpected, as the Michigan data were obtained from a greater number of specimens. The average diameter of the Michigan specimens is approximately in agreement with those of Rogick's New Ybrk specimens. These data indicate that the zooecial diameter of Plumatella repens is highly variable. Ectocyst Allman (1856) states, "The quantity of earthy matter deposited in the ectocyst is small, and this tunic is generally more pellucid than we find it in most other species of the _39_ genus; it varies however, in this respect, according to age and locality of growth." His illustrations (Plate 5) are of transparent zooecia. Toriumi (l955d found only two specimens with heavily incrusted ectocysts. His specimens vary from naked to slightly incrusted. Approximately 70 per cent of Michigan specimens lack incrustation. 'Four specimens have ectocysts with a somewhat frosted appearance, seemingly attributable to the uniform deposition of very small siliceous particles on the surface of the ectocyst. Some 20 per cent have moderate incrustation, and one specimen has heavy incrus- tation. The color of the ectocyst is, typically, pale-yellow to yellow-brown or reddish-brown. In three specimens the ectocyst is essentially hyaline and somewhat inflated, super- ficially suggesting the genus fiyalinella. Longitudinal striations are noted on the zooecia of colonies from 14 collection sites, most often on the naked, frosted, or slightly incrusted colonies. These striations were of com- parable occurrence in specimens examined by Toriumi. The sclerotization of the ectocyst is variable in the Michigan specimens, the stiffness being greatest on the darker coenecia. White dots were sometimes noted on the endocyst of young zooecial tips, as they are on some §y§l_- ‘ggllg punctata zooecia. Some agglutination of the ectocysts was noted in eight specimens. Septation Allman (1856) states that "transverse septa are most apparent", in the elongated zooecia which are free of the —40- substrate. He continues, "I have met with specimens of the free variation of this species in which well-formed septa occurred between almost every cell." He illustrates the periphery of these septa (Plate 5, Figure 4) by dark lines. Their extent is not evident. Rogick (l940;1?late IV, Fig. 18) shows no septa in her drawings. Toriumi (1955a) indicates that septa in foreign specimens from the United States, Canada, Europe, Manchuria, and Japan are similar and that only four specimens have septa at the origins of the branches and then only rarely. However, in specimens from the Kurile Islands the septum is present in almost each zooecium of largely repent colonies. With respect to septation, certain other- wise typical Michigan colonies depart somewhat from Toriumi's data. Although over 50 per cent of my specimens are without septa, collections from 14 sites have septa at the base of nearly all zooecia, seven others have septa at the origins of branches, and 16 others have occasional septa. The fungoid colonies have the most frequent septation both in the repent and free branches. The septa are largely of the round peripheral type, and a pale yellow-brown in color. Only five specimens have the stiff, brownish septa with the elongate perforation, so frequently encountered in Plumatellg emarginata. A septum Similar to the type frequently found in E. emarginata zooecia is shown in Fig. 6. The elongated perforation is even narrower in some E. gmarginata septa. Thus, with regard to septation, many of the Michigan colonies have their greatest affinity with Allman's specimens and with -—41-. those from the Kurile Islands. Tentacles The number of tentacles, according to Allman, is "about sixty", while the number given by Jullien (1885) varies between 44 and 53, most frequently between 49 and 53. Toriumi (1955a) gives a range of 39 to 65 with a central range of 51.1 to 52.7. His Tsuta-numa specimens range in number from 53 to 72 with a central range of 60.7 to 63.9. The number of tentacles of the Michigan polypides compare very closely with Toriumi's non-Tsuta-numa specimens. They number 38 to 65 with an average of 53.5 in 389 counts. Toriumi indicates that the tentacle number of newly evaginated ancestrulae is 18 (12 outer, 4 inner, and 2 anlages). I have counted tentacles on newly evaginated ancestrulae found in a woodland ditch in Saginaw County, which varied from 12 to 19. The most frequent counts were 16 and 17. Other ancestrulae counts have been taken ranging between 24 and 28. Floatdblasts The sizes and ratios of the Michigan specimens are in agreement with those obtained by other investigators. Stato- blast measurements are given in Table 2. Reticulations on the capsule are variable in distinctness, and they are less evident or absent on the dorsal side, in agreement with Toriumi's observations. Mammillations are present, and usually best developed on the dorsal side and along marginal areas. The float coverage is, in most cases, very typical. The ventral surface has only a thin float nearly equal in __42__ TABLE 2. Plumatella repgns measurements Source fronvwhieh Number ‘Whole statoblasts measurements were of Length Average ‘Width Average Ratio taken measurements in In. length in mm. width length to width Floatoblasts Present study 252 0.30; 0.35 0.22: 0.26 131.32 Kraepelin (1906) l ? 13108.1:135 Rogick (1940) 277 0.26; 0.333 0.223 0.243 0.45 0.41' 0.29 0.28' Hosawa and I Toriumi (1941) i . i 2. {goes 0.35; l 0.21; f 0.37 0.23 Borg (1941) ‘ i 1.1.20 iaeourt (1951) 0.353 ' 0.273 0.38 0.28 Toriumi (1955a) 0.33. 0.37; 0.24; 0.27; 1.2.1.5 } 0.41 . 0.38* 0.31 0.289 (Av. 1.21124).- l I Sessoblasts ' Present study 85 0.38: 0.60 0.313 0.38 l§1.31 0.68 0.47 Rogick (1940) as 0.42; 0.47 0.28; Hosawa and E Toriumi (1941) ! £3 fuggoga 0.80 0.39 Laoourt (1951) 0.563 0.43; 0.60 0.52 Toriumi (1965 .) 0.361 0.43; 0.27; 0.32: 0.51 0,45. 0.40 l 0.34: i * Rogick and Toriumi give their averages as a range, therefore they can only be compared approximately with other averages. -43.. -- _.~——-—~_—-_——_-—~_—..—~----.—_— _.--.—_— ...4— ““ —--—..— _—_-.-——. V _,. _ .— Hunber Ca sule .n1i_ .__ of Length Average Width Average Ratio measurements in mm. length in mm. width length to width 177 0.19: 0.27 0.18: 0.22 1:1.23 0.39 0.29 277 0.24: 0.265 0.183 0.203 0.31 0.27. 0.26 0.22"I s E I 9 y i i 0.23; 0e28, Gels! 3 0e223 lelgle4 : 0.33 0.299 0.26 g 0.23‘I (Av. 1.21.1.24)* E ; 1 ? * § 85 i 0.30; 0.41 0.27; l 0.30 131.36 0.56 0.37 3 i 83 0.36; 0.37; 0.25; 0.283 0.45 0.41m 0.36 0.30* ! -44- width at the ends and sides of the statoblast, and the dorsal side has somewhat more float coverage at the tips. Variations in the amount of float coverage are more apparent on the dorsal side of the floatoblasts. Differences in float coverage and shape of Michigan 2, repens floatdblasts are illustrated by Fig. 7 through 10. A floatoblast, with an incomplete float, is shown in Fig. 11. Where the true float is absent, only a thin reticulate lamella is present, similar to that found in the sessoblast. Naked capsule (area of capsule not covered by float cells) measurements are as follows: Range of lengths and.widths, respectively; dorsal side, 0.12 mm. to 0.26 mm. by 0.10 mm. to 0.23 mm. and ventral side, 0.17 mm. to 0.32 mm. by 0.15 mm. to 0.25 mm; the average length and width of the dorsal side are 0.20 mm. by 0.17 mm., and the averages of the ventral side are 0.25 mm. by 0.19 mm. The statoblasts with somewhat greater float coverage than usual, are often similar in appearance to Pateff's (1924; Fig. l) illustration of a‘fi. repens floatOblast. Sessoblasts The measurements and ratios of the Michigan sessoblasts given in Table 2 conform to those of other investigators, although the maximum is somewhat higher (Fig. 12). The width of the lamella given by Toriumi (1955a) ranges between 0.30 mm. and 0.80 mm. The Michigan specimens have lamellae which agree with these figures. Rogick (1940; fig. 20) shows a sessoblast on which the lamellar reticulations are clearly evident. Toriumi declares that his specimens have an obscure -45- “uranium. m5 .3 Fe .1315“; 4: 3pm t 1 3 doves-1:». 5 52,7? Smashed \lewhul Suvface. .‘1____ Fig. septum rom a “Swid‘idom, aha Fl +bt‘t 11‘ (I ®:s:(°s:¢2mc €61.10. Flmbbhsl‘ dovSoJ Stu-(00: l I l 1 cfirs““§ é - ’ \c, (vafiogtovix i%fi)on5 {was-4+ ‘ * '" H on can 9.3.11. Detect-‘0: {lodoblnst Lon \Qmelko. edeeat is Pkg-re. \vuower PoiHa $63.13.“ ‘\') sessoblast- S w'm distinct Ye‘h‘ {ens flelomeua. -45- and sometimes distinct reticular pattern on the lamella. The sessdblasts of the Michigan specimens have distinct lamel- lar reticulations in most cases (Fig. 13). In only a few are they obscure and in only one specimen is the reticulation absent. It is possible that the sessoblasts which lack reticulations are immature. Mammillations are clearly evident on the capsules of the Michigan 2. repens sessoblasts. Detour Harbor, Chippewa Count , Specimen This specimen of‘g. repens is atypical and requires special comment. The small and compact colony was developed from a floatoblast, and the branches radiate sinuously from this point of origin. There is little elongation of the zooecia, and often two to four zooecia lie parallel and closely con- joined; thus, the individual contour of the zooecia is often obscure. The zooecia are repent and wide, averaging 0.664 mm. in diameter.‘ The zooecial tips are short with numerous lamellations around the distal portions. The massive hyaline and thick zooecia are suggestive of Hyalinella pgnctata. The (ectocyst is stiff and somewhat incrusted. Other characters suggest Plumatella emarginata; a sometimes distinct and broad keel, hyaline furrow, and emargination on the tips of the incrusted zooecia. In some places distinct indentations on the surface of the coenecium form.what may be called rugosities. Longitudinal striations are also evident on some of the zooecia. The light incrustation is whitish in color. This is the only form collected which has charac- teristics of both‘g. punctata and E. emarginata. The form -47_ was classified as Plumatella repens on the following basis: tentacles approximately 60; septa absent; typical 3. repens floatoblast; typical 2, repens sessoblast with distinct lamellar reticulations; stiffness of the hyaline ectocyst. The colony is decidedly unusual and the author has not found a similar form in the literature. I believe that the charac- teristics have been largely dictated by the environment. The colony was situated in a small concave despression in a rock, on a wave washed shore. The nature of the small deep concavity and the agitation of the water may have retarded the elongation of the zooecia, encouraged lateral expansion of them, forced them into close apposition, or checked thelelongation 0f the zooecial tips. The rugosities and lamellations may be the result of physical confinement by the sides of the concavity. The colony by adhering to the contour of the substrate, developed a concavity on its own dorsal surface. The physical stress of this dorsal concavity caused wrinkling and resulting rugosities of the colony surface. The development of the keel and furrow may likewise have been dictated by the sub- strate contour and the movement of the water. Plumatella emarginata Allman 1844 Colony The Michigan specimens vary from widely open and repent to dense with many zooecial branches entangled and free of the substrate. The dense growth form was originally des- cribed by Allman (1856) as Alcyonella benedeni. Kraepelin (1887) includes three varieties under his Plumatella princeps, —48— var. spongiosa, muscosa, and emarginata. Braem (1890) was of the opinion that both gpongiosa and muscosa were variations of Plumatella emagginata. Toriumi (1952e) reared colonies which had been germinated from statoblasts of luxuriant colonies, and new branches assumed a widely open orientation. He has confirmed Braem's opinion by finding that variation depends on substrate, budding rate, and the relative elongation of the zooecial tubes. The varieties would thus be pheno- types of the same species; var. gpoggiosa is the highly luxuriant growth form, and var. muscosa ( and Allman's Alcyonella benedeni) somewhat less luxuriant growth forms, while var. emarginata is the open form. I have noted free branches in approximately 25 per cent of the Michigan colonies. This is more frequent than Toriumi has reported from Japan. Zooecia Both rounded and truncated tips were observed frequently. Wrinkles, called annulations (sometimes lamellations), were noted at the tips of approximately 25 per cent of the zooecia (Fig. 14). Toriumi (l952e) states that these annulations on Plumatella Emerginata are not related to season or locality, and that Plumatella casmiana is the only other species with these characteristics. However, the author has observed rather well developed terminal annulationson older zooecia of Flumatella repens from four collection sites and weakly developed annulations on certain other specimens. Meat 3. ggpgpg colonies with these annulations are essentially typical in other characteristics. __49_ Marked taper was only rarely noted in the zooecia. Annandale (1910), Vorstman (1928 a,b) and Toriumi (l952e) are among those who have commented on the essential uniformity of width of the zooecia from proximal to distal end. Two collections were made of flumatella Allmani type colonies where the taper toward the proximal end was marked and where some taper was evident at the distal end. These colonies have a clear furrow and emargination and a weakly developed keel. The zooecia vary between 0.215 mm. and 0.44 mm. in diameter proximally and 0.249 mm. and 0.52 mm. distally. Rogick (1940) gives zooecial diameters ranging from 0.31 mm. to 0.45 mm. with a median range of 0.34 mm. to 0.40 mm. The Michigan forms are closely in agreement with hers. The keel is strongly developed throughout the length of the zooecia in nearly 50 per cent of the Michigan Plumatellg emarginata specimens, weakly developed or developed only distally on some 40 per cent, and essentially lacking on two specimens. The furrow is moderately to clearly evident on approximately 90 per cent of the specimens, obscure or lacking in 10 per cent. The emargination is present on most specimens and largely obscure in two specimens. R0gick and Van der Schalie (1950) state that the zooecia of their collections are "noticeably keeled". The keel, furrow, and emargination have all been traits of specific value and were recently reevaluated by Toriumi (l952e). He states that all colonies which he has examined have a furrow on some of the zooecia, all have a keel, though often obscure on the free branches, and all have at least a few emarginate zooecia. In the present study, when one or two zooecial traits were largely obscure, other specific traits were determinative. Zooecial tips are depressed or flattened against the substrate in nearly 50 per cent of the Michigan specimens. Ectocyst Allman (1856) describes the ectocyst as being heavily covered with minute and agglutinated siliceous particles except in the immediate vicinity of the orifice. Toriumi (l952e) reports that the ectocyst is incrusted with a variety of materials which give it various colors, usually grey, yellowishrbrown, or black. Annandale (1910) speaks of the dark brown to black color of the ectocyst. Six shades of color from whitish-grey through reddish-brown to black occur with nearly the same frequency in the Michigan specimens. Black colonies with whitish tips were collected from four collection sites (Fig. 17 and 18). Light-colored zooecial tips were noted in a majority of the Michigan specimens. In a number of cases the incrustation is not securely imbedded in the substance of the ectocyst, but rather loosely imposed. With careful scraping, this loose incrustation could sometimes be removed revealing the nearly transparent yellow-brown ecto- cyst beneath. In newly formed zooecia, the ectocyst is medium soft gelatinous and hyaline. In a few cases the ectocyst is) not incrusted. In collections from one location in Wintergreen Lake, unincrusted colonies were present with E. repens, and the colonial aspect of both species is similar. Borg (1936b) -51... describes an entirely transparent and hyaline colony of E. emarginata from Africa. Toriumi (1954a) speaks of the agglutination of ectocysts in luxuriant colonies of 3. emarginata and Plumatella fungosa. The author noted extensive agglutination of ectocysts in luxuriant colonies and in flabellate colonies from Spring lake, Ottawa County, and Van Etten Lake, Iosco County. Toriumi records that longitudinal striations on the ecto- cyst are present in specimens from Japan and vicinity and from Tahiti, but that he did not find them on specimens from North America, Sweden, Holland, and Czechoslovakia. Striations are present on several zooecia of colonies of 2. emarginata collected from two lakes in Michigan. They are evident on 15 to 20 per cent of the Michigan colonies of E. repens. m The presence of septa is not indicated by Allman (1856). Annandale (1910) states that partitions are present. Toriumi (19526) states that generally each zooecium of a repent or open branch has a septum, The number is variable, and some- times they are present only at the origin of the branch. Septa are present to some degree in all of the Michigan speci- mens with the exception of one very young colony and one colony fragment. In approximately 60 per cent of the speci- mens, septa are present in each zooecium. The septa of 3. emarginata are usually very dark and stiff and may be arched or moon-shaped. Often the communication between zooecia is only a narrow vertical portal or no more than a slit-shaped -52- perforation. However, the septa inlfi. repens are frequently not so dark and stiff and more often have circular perforations (i.e., peripheral septa). There are exceptions, of course, but the thin vertical perforation is approximately five times more common in‘fi. emarginata study colonies than in partitioned ‘2. repens colonies. Thus septation is of some aid in syste- matics. Tentacles The following tentacle numbers are given by several investigators: Allman (1856) "about 40"; Kraepelin (1887) for Plumatella princeps, 28 to 42; L0ppens (1908), 42 to 54; Borg (1936b), 40 to 50; Lee (1936), form typica, 40 to 44, and form benedeni, 30 to 32; Rogick (1937), 40 to 54; Rogick (1940), 30 to 42; Hozawa and Toriumi (1941), 36 to 42; Toriumi (1952s), 20 to 51. The counts on the typical Michigan speci- mens varies from 26 to 54, with an average of 40.6. There are thus wide variations, causally associated by Toriumi with environmental conditions. In the present investigation, variations in tentacle numbers among colonies from different locations of the same lake corr0borate this assertion. Low tentacle counts of 14 and 15 were taken on two ancestrulae. Floatoblasts Table 3 reveals that colonies of the typical Michigan 2, emarginata produce floatoblasts of such variability that the length and width measurements (both whole and capsule) nearly encompass the entire range of variation reported by earlier investigators. The length and width maxima and minima are TABLE 3. Pflu-atella emrginata masurenents Source from which lumber Whole statoblasts assurenents were of Lingth Average width ’ Average Ratio taken measurements in 3. length in In. width length to width floatoblasts Present study ' (typical) as 0.33; 0.41 0.20. 0.25 1.1.04 0.60 0.32 ‘ (Pm Creek fern) 67 0.26: 0.36 0.20: 0.24 141.46 0.37 0.27 Braem (1890) 0.47: 0.49 0.26: 0.26 0.62 0.27 Kraepelin (1906) 0.36: 0.21: 0.60 0.31 I”? (1913) 0e338 0.37 0.22! 0.24 131.5‘ 0.42 0.26 Abricossoff (1927.) ‘ Moscow for: 0.60 0.27 Vladicauoas 0.46 0.26 Vex-stun (192891) 0.37: 1.1.1.1:2 0.60 Lee (1936) 0.34 0.20 Borg (19361:) 0.46 0.21 Hastings (1938) I,” 11 0e“ 0.30 131e63 11051.1: (1940) 94 0.35; 0.40; 0.21; 0.23; 0.47 0.46"I 0.31 0.26. Hozawa and 0.37: 0.21; Toriumi (1941) 0.42 0.24 Berg (1941) 181.60 lacourt (1961) 0.42: 0.23; 0.60 0.27 Regiek and 0e“ 0e23 131e88 Vendor Schalie (1950) 10’1““ (19520) 0e“: 0e203 1e“.1e71 0.46 0.27 1' Rogick gives her a‘verage as a range. compared approximately with other averages. Therefore it can only be Number Capsule _.“w of Length Average Width Average Ratio .Ieasurenents in mm. length in mm. ‘width length to width 66 0.23: 0.27 0.18: 0.21 1:1.29 0.32 0.23 48 0.22: 0.23 0.17: 0.18 1:1.25 0.26 0.19 I 5 x 0.29 0.27. 0.23 0,214 0.26: 0.188 0.28 0.20 0.28 0e21 1:1e36 0.23: 0.26: 0.17: 0.198: - 1.30.1.33 0.30 0.27* 0.23 0.203* ‘ Rogick and Toriumi give their averages as a range. Therefore they can only be compared approximately with other averages. TABLE 3. (continued) Source from which lumber Whole statoblgcsts m measurements were of Length Average Width Average Ratio taken measurements in m. length in -. widfl: length to width Sessoblasts Present study (typical) 26 0.38: 0.44 0.30: 0.34 1:1.32 0.62 0.40 (Pony Creek form) 22 0.43; 0.40 0.30; 0.34 1:131 0.60 0.36 Harmer (1913) 0.32: 0.44 0.32 0.34 181.32 0.48 0.37 Vcrstsmn (1928a) 0.46 Borg (1936b) 0.39 0.31 Hastings (1938) 0.48 0.36 131.33 Rogick (1940) 19 0.40: 0.44: 0.27: 0.303 0.68 0.470 0.36 0.33. Borg (1941) 111.23 Rogick and i 0.46: 0.368 Vander Schalie l 0.47 0.39 (1960) ! Lacourt (1961) l 0.50 0.38 * Rogick gives her average as a range. compared approximately with other avenges. Therefore it can only be _.55._ Number of length measurements in mm. 20 0e30, 0.46 22 0.363 0.43 17 0e353 0.48 0.40 ' Average length ‘;--s "w.-- a. V -}.. 0.38 0.58 0.38; 0.40* 0.22: 0.37 0.25: 0.35 0.253 0.31 0.29:- 0.35 Average ~Ratio width length to width 0.28 1:1.36 0.27 ( 1:1.36 l I I 0.278 0.29. -57- only slightly more inclusive than Rogick's (1940). The length- width ratios are consistent with those of Toriumi and never reach the extremes given by Hastings (1938) for type I, or by Vorstman (1928a). The floatoblasts measured by Rogick (1940) and Rogick and Van der Schalie (1950) are somewhat narrower than those of the current study. The tips of the Michigan floatoblasts are either truncate or rounded, often comparable in design to those in Plate I, Fig. 1-5 of Rogick and Van der Schalie. The ventral and dorsal surfaces of the typical Michigan ‘3. emarginata are shown in Fig. 15 and 16. Some variability is noted relative to float coverage with the float in extreme cases covering nearly the entire dorsal surface. The dorsal surface is decidedly flat with a tendency to round only at the peripheral margins of the float area. The ventral surface is typically convex and less covered by float portion. Thus the naked capsule area on the ventral side is greater. The average length and width of the naked capsule are as follows: dorsal side, 0.11 mm. and 0.09 mm.; ventral side, 0.20 mm. and 0.17 mm. The float coverage agrees with figures and illustrations given by Rogick (1940) and Rogick and Van der Schalie (1950). The suture line of the float is visible on dorso-lateral surface of the statoblast. Mammillations are generally uniform and complete on both surfaces. Sessoblasts The measurements of the fixed statoblasts agree with those given by other investigators (Table 3). The mammillations are —58- “annotate. Mint“ 51.14. Zooeciuum. Annuicdfi‘ons Cure visu'blto ab Y‘ - “k i 'iu‘o edogx. c “6.9mm ns affine L 94.15. fimlobmgt {-323.10 filoaioblqst dofyd wean “QM SulfacQ -59- complete and uniform on the dorsal surface. Distinct reticu- lations on the capsule are frequently present. The lamella, or vestigial annulus,is somewhat narrower on 2, emarginata than on.£. repens. Toriumi has reported that the lamella of of both.§. repens (1955a) and‘g. emarginata (1952e) has obscure reticulations. However Rogick (1940; plate V, Fig. 20 and 24) shows clear reticulations. A partial or complete reticular pattern is evident on the sessdblasts of approximately 40 per cent of the typical Michiganlg. emarginata sessoblasts, while it is obscure or essentially lacking on the remainder. Reticulations are clear on nearly all of the‘g. repens speci- mens, being obscure on only two. Therefore only partial taxonomic value may be given to this character (1.0., when distinct reticulations are absent, supportive evidence for g, emarginata is enlisted, but when distinct reticulations are present, other characteristics must be wholly determinative). Plumatella emarginata, flabellate form Allman (1856) discusses two species, Alcyonella flabellum Van Beneden.1848 and Plumatella Ingalis Allman.1850, founded essentially on their geminate fan-like growth form. The former species was described as dense, with zooecia con- tiguous, and the latter was widely open in form. Jullien (1885) contends that the twin-like character of these two forms is not a basis for specific separation. He places these forms under 3. repens. Abricossoff (1927b) suggests that flabellum is a seasonal form. Rogick (1941) discusses these two geminate forms and gives measurements for the Jugalis form but leaves —6‘«- their systematic position undecided. Toriumi (1952d), by means of rearing experiments on statoblasts, concludes that geminate colonies do not originate from statoblasts but come from larvae, which generally have two incipient polypides. These polypides germinate in opposite directions. All gemi- nate colonies oflg. emarginata examined by Toriumi are of the Jugalis type. The variation flabellum has not previously been reported for Michigan. Rogick and Van der Schalie (1950) reported the collection of‘g. repens jugalis from Michigan. It is not certain whether their form was‘g. repens or'z. emarginata, as all Plumatella forms were classified under repens at that time. Flabellate and intermediate flabellum~ Jugalis type colonies were found in Van Etten Lake, Iosco County, and in Spring Lake, Ottawa County during the present study (Fig. 17 and 18). Two of the specimens more nearly like the Jugalis form had originated from contiguously located sessoblasts which had germinated simultaneously. The polypides had germinated essentially facing each other, and so one ancestrula had crossed the other in elongating, leaving a narrow connecting portion of the zooecium.between the two subsequently formed flabellate portions of the colony. The author noted one geminate and flabelliform colony which had developed apparently from two contiguous floatoblasts. The ventral valves of these two statoblasts remained loosely attached to the narrow interconnecting zooecial area between the colonies. The dorsal valves were no longer present. The basal portions of the two ancestrulae had fused nearly completely, -61... Wumdella emu-(13 natq, F“ ~11 Ce‘fi'e‘t: Udbelhke opLovfies Lower ‘8 +1 \lou“ . 5‘8“»; will”? Qkflodh‘ (Calm-Is H8m\ Hack En Cdor wH-la wkch‘sk +~p$ 'VVI C9‘ “Y R‘Y‘w‘ Show‘m (Lotion ivfitrmecflpadg @9111.) (“at \LLum and “an5 iforms. CNoi-e dark séSSobLaSTs {a vu‘finfl. Co\oV\ . This. dole or: {him (Vow. setsebla 6" y- — 1‘ - and they had elongated away from the point of origin giving rise to geminate flabelliform colonies. During the present study extensive agglutination between the soft gelatinous bases of newly germinated ancestrulae of Plumatella repens has been observed. The author suggests that the soft gelatinous ecto- cysts of two oppositely directed but contiguous ancestrulae may thus agglutinate, with the fusion so complete as to make it difficult to determine whether the two resulting flabellate colony portions had originated from one larvae or two floato- blasts. This postulate presupposes the loss, subsequent to germination, of the statoblast valves. The two dorsal valves had been lost in one of the cases already cited. Valves would be detached most readily from colonies growing along wave- washed shores (Spring Lake) or in flowing water. One geminate form was found with a thin zooecial connection between the flabellate portions as pictured by Allman (1856; Plate 4, Fig.2) and Braem (1890; Plate II, Fig. 17 and 18). No statoblast valves were seen. This colony may have originated in the manner just discussed or from a larvae as suggested by Toriumi. The flabellate colonies from both Van Etten Lake and from Spring Lake are typical Plumatella emarginata colonies with nearly black, white-tipped zooecia. The development of flabel- liform.colonies depends upon a rapid budding rate or a reduced elongation of the zooecia, and upon the parallel orientation of the zooecia and their branches. In summary, observational evidence and discussion are presented for the origin of geminate flabellumptype colonies -53- from the simultaneous germination of two contiguous statoblasts in conjunction with the fusion of the bases of these statoblasts and the subsequent loss of the valves. Plumatella emarginata, Pony Creek form The characteristics of this form, collected at six sites, are consistent and intermediate between those onglumatella repens and Plumatella emarginata. There has been much dis- agreement among bryozoologists with respect to the systematic distinctness of Plumatella emarginata and Plumatella repens. '2. emarginata has been placed in, or taken out of, synonymy with.§. repens a number of times by various investigators. Specimens of one of these species often reveal one, two or sometimes three characteristics which are associated with the other species. However, this taxonomic intergrading is most often confined to a minority of individuals in a population. The present discussion concerns a form which is consistent from one population to another, and which has intra-pOpulation stability. This form may be compared to Plumatella ele ans, because the characters of that species, as defined by Allman (1856), are embodied in the phenotype of the Michigan specimens. Likewise there is much agreement between the Pony Creek form, which the author has tentatively placed under'z. emarginata, and Plumatella lgvanica. The consideration of this Michigan form again raises the question of the relationship between '2. emarginata and‘g. repens. The author agrees with those who have favored species status for these two Bryozoa. How- ever, such agreement fails to illuminate the position of -64- reasonably consistent intermediate forms. Environment is known to modify the phenotype of freshrwater bryozoans, but a consis- tency of characters among several populations argues against a purely environmental shaping of this phenotype. ‘3. emarg - [2535 and‘g. repens appear to be very closely related, but this close relationship does not preclude the existence of inter- mediate species. On the other hand, hydridization may occur in the family Plumatellidae. Diagnosis: Plumatella emarginata, Pony Creek form Colony The colonies collected during this study are repent. The branching is widely open,and the tips are often raised from the substrate. Zooecia The zooecia most often have a very gradual taper. However, some colonies at two collection sites have clavate zooecia. The zooecia vary in diameter from 0.24 mm. to 0.44 mm. proxi- mally and from 0.34 mm. to 0.55 mm. distally. They therefore tend to have greater width distally than‘g. emarginata, but do not attain the higher maximal dimensions of P, repens. A feeble keel is present only distally on approximately- one-half of the specimens, but it is more strongly defined on the remainder. The furrow is seen on some zooecia in each collection, and it occurs frequently in two of the collections. On three or four zooecia of the Vermillicn Creek colonies, the var. furcifer furrowing was evident (1.9., the proximal bifur- cation of the unincrusted furrow into two obliquely proceeding -65.. lateral lines). The emarginate orifice is seen on zooecia of all colonies, but not with the same frequency. The above traits are particularly well deveIOped on the Pony Creek specimens. Longitudinal striations are visible on the zooecia of colonies from two collecting sites, while sub-orifice annulations occur in a single case. ,Ectocyst Incrustation is moderate to heavy with the exception of a few Wintergreen Lake colonies which were nearly naked and grey-yellow in color. Incrustment appears to be the usual condition. Siliceous particles and detritus make up the incrustation. The color is most often whitish-grey to yellow- brown. The zooecial tips of one-half of the specimens have whitish tips. gems. In small or fragmentary colonies, septation is lacking or only occasionally present. In most colonies septa are numerous. The Pony Creek specimens have dark, stiff, and frequent septa. Tentacles The average tentacle number is 45.5 (on 158 counts), while the range is 40 to 54. The lowest of the range figures and the highest of the range figures represent approximately the lowest and highest recorded counts for‘z. repens and'g. emargi- _n§ta respectively. The average number of tentacles is inter- mediate between these two species. —66— Floatoblasts The statoblasts are of particular significance in this form. They are intermediate in every way. The maximal length is below the maxima for bothIg. repens and E. emarginata. The ratio of whole length to whole width, 1:1.45, is indicative of a statoblast narrower than‘fi. repens, yet wider than'fi. emarginata. The capsule measurements are not significant. The float coverage (Fig. 19 through 22) is lesser on both dorsal and ventral sides than in the typical‘g. emarginata, and it is greater than in 2. {92353. The float coverage is consistent, and the average lengths and widths of the naked capsule are as follows: dorsal side, 0.15 mm. by 0.14 mm.: ventral side, 0.22 mm. by 0.17 mm. The dorsal side is flattened‘ma.tends to round more at the margins than in‘g. emarginata, thus bringing the suture closer to the center line. mammillations are relatively even and complete on both capsule surfaces. Sessoblasts The sessoblasts are not particularly distinctive. How- ever lamellar reticulations are reasonably well developed on all of the sessoblasts examined, a characteristic shared with 2. repens . Discussion Jullien (1885) includes Plumatella elegans and 3. emargi- ‘ggtg unterlg. repens. Kraepelin (1887) places 2. elegans in synonymy, along with‘g. repens, Plumatella fungosa, Alcyonella flabellum.and other forms, within his species Plumatella -57- BM mam (Pony Creek {ox—m) {\od’eblafl-s ,._. 3 \ Fm‘J‘). Dorsal surface F' {1.10. Dermal Surface. 75:3. 21.Devsal surface. F€%_22. Ventral Sur ace. (ehq‘t Cell Clem-(Y evident) —68— polymorpha. Thus it is separated from‘g. emarginata which he includes in his Plumatella princeps group. Braem (1890) considers Plumatella elegans synonymous with.§. repens. Toriumi (1952s) states that the statdblasts of.§. emarginata fall generally into two catergories, those of type I and those of type II of Hastings (1938). He states that the floatoblast of Z. elegans appeared to agree with type I of 2, emarginata. So contrary to the opinion of many workers, 2, elegans should be regarded as a synonym of‘z. emarginata. I agree that‘g. elegans conforms more closely tolfi. emarginata, but I do not agree that the type I statoblast of Hastings (1938) agrees fully with the floatoblast of‘g. elegans. Allman (1856) states that "the statoblasts are broad, ellip- tical, with a widely overlapping annulus; they are narrower than those of'fi. repens, but wider than the ova of.§. emargi- ‘2223, and present no tendency to the bean-shaped figure of the latter." The ratio of length to width of Hastings type I statoblast is 1:1.8. An examination of Table 5 discloses that this ratio is not intermediate in width between E. repens and '2. emarginata, but is actually in the more narrow range even for‘fi. emarginata. Even the typical Michigan‘fi. emarginata is narrower than Hastings' type I statoblast. Type II stato- blasts agree more closely with the Pony Creek form as she gives a ratio of 1:1.55. Thus the statoblasts of the Michigan Pony Creek specimens are truly intermediate in width between the two species. _59_ Allman illustrates only one face of the statoblast for Plumatella elegan . The float coverage and round naked capsule area closely resemble the dorsal surface of the Pony Creek form. If Allman's drawing represents the ventral face of the capsule, the dorsal face would have still greater coverage by the float, and would in effect have the typical emarginata float coverage. Neverless, in comparison to 2. repens, the float is more widely overlapping in both 3. elegans and the Pony Creek form. Other species which the Michigan specimens resemble are Plumatella Javanica and Plumatella vorstmani. '2. javanica was described by Kraepelin (1906). The zooecia are similar to the Michigan specimens in that branching is often infrequent and zooecia tend to be elongate. Kraepelin's Fig. 2 shows the distinct furrow and emargination, and is identical in appearance to a number of the Michigan specimens. Annandale (1910) states that‘g. Javanica, which he found abundant in Calcutta, is related to‘fi. emarginata but is distinguished by the infrequently branched linear series of zooecia. He states further that the "zooecia are entirely and invariably recumbent." This is also true of the Michigan specimens. Annandale declares that there is never any "trace of pigment in the ectocyst, which is markedly transparent and delicate; the external surface is smooth." The Michigan colonies are either without pigment or pale yellow, and most often incrusted. Annandale gives no tentacle data, but Kraepelin gives the tentacle number as 45, and this is in excellent agreement with the Michigan specimens. Vorstman (1928a) considers Kraepelin's -70- number "a mistake", and states that the Javanese collections have only 20 to 27 tentacles. The floatoblasts shown by Kraepelin (Fig. 3) and described by Annandale have less float coverage than my specimens. Vorstman shows (Fig. 4) a floato- blast somewhat similar to the Pony Creek form but narrower, having a length to width ratio of 1:1.6. She describes the sessOblast as somewhat smaller than the floatoblast. Thus the Plumatella javanica sessoblast does not agree with those of the Michigan specimens. Toriumi (1952c) gives particular importance to the small size of the sessoblast, in erecting the new species, Plumatella vorstmani. He placeslg. javanica, as described by Vorstman, in synonymy with his new species. The Michigan colonies are in better agreement with Toriumi's .2. vorstmani than they are with Kraepelin's and Annandale's description of 2. javanica. This is largely because he des- cribes the ectocyst as being naked to slightly incrusted, and also states that a slight keel, in addition to furrowing and emargination, may be present. The zooecia shown in his Fig. 3 and 5 are described as heavily incrusted, and frequently have the keel. Toriumi's Fig. 4, showing a linear sequence of zooecia, some of which are elongated, resembles colonies from the Thunder Bay River. The floatoblasts of Toriumi's specimens are strikingly similar to the atypical Michigan floatOblasts in size and float coverage. The round naked capsule area on the dorsal side, also the elliptical naked capsule area on the ventral side are the same in both forms. Toriumi gives __71__ a length to width range of 1:1.59 to 1:1.74. This range over- laps the average ratio of 1:1.45 of my specimens. His average ratios of 1:1.55 to 1:1.59 are somewhat higher and essentially within the range of the widest Plumatella emarginata floato- blast. Plumatella vorstmani differs from the Pony Creek group in the following characteristics: incrustation is not frequently so heavy; the keel is not as distinct or frequent; no septa are present; the tentacle number is considerably lower than in the Michigan form, ranging between 18 and 52, and the sesso- blasts are smaller than the floatoblasts. Plumatella ele ans, Plumatella Javanica, and'g. vorstmani all share many characteristics with‘g. emarginata and particu- with the Pony Creek group. However the differences between these forms and E. emarginata, and even the Pony Creek group, are of sufficient magnitude to advise against taxonomic combinations at present. Allman's (1856) E. elegans relates closely to the Pony Creek form, but is incompletely described in terms of the more recent systematic characters. Thus, the Pony Creek form is intermediate in many characteristics between ‘3. repens and‘g. emarginata and likewise between P. emarginata and the European, Javanese, and Japanese forms with which it has been compared. Future systematic study may prescribe a species or sub- species status for the Pony Creek form. However, such a recommendation at the present time does not appear appropriate and would possibly only serve to amplify the complexity already _|72._ existing among intergrading forms. The Pony Creek group shares a greater number of characteristics with the cosmo- politan‘g. emarginata, and for this reason is delegated to this species. The fact that the two forms have not been found in the same habitat acts in support of this decision. The information and discussion which have been presented serve to highlight some of the extensive intergradation which exists among members of the family Plumatellidae. A similar overlap exists among other forms in this family, and some of the systematic separations appear tenuous. A thorough examination of the world-wide members of the family Pluma- tellidae would be of taxonomic value. The results of such a study could conceivably make possible a systematic revision of the fresh-water Bryozoa in terms of polytypic species and subspecies, as discussed by Mayr, Linsley, and Usinger (1955). Cain (1954) refers to the merit of the term."semispecies" as suggested by Mayr. This designator may also have application in bryozoan taxonomy. Plumatella fruticosa Allman 1844 Colony Plumatella fruticosa has not heretofore been recorded from.Nuchigan. Collections of this species were Obtained from 10 localities during the present investigation. The colony described by.Allman is attached only at its origin. Toriumi (1954» states that the colonies vary from repent to shrubby in appearance. This shrubby appearance is found in Frederi- ggllg sultana, and Toriumi (l952b) indicates that the free _73_ branches of Plumatella osburni also show this characteristic. Colonies found in five Michigan collections are largely repent; those in four, have both repent and free portions; those in one, are largely free of the substrate. The branching is shrubby on the free portions and.0pen in pattern. The most luxuriant colonies were collected from Clark Lake, Luce County. The zooecia are most often erect or nearly erect, and the zooecial tips are usually raised a distance of 0.8 mm. to 1.2 mm. above the substrate. The vertical zooecia of the Muskellunge Lake, Montmorency County, specimens are frequently in excess of 2.0 mm. above the substrate. Wiebach (1952) discusses the release of statoblasts in Plumatella fruticosa from a "hyaliner cysts". The statoblasts pass into this thin hyaline protrusion from the side of the vestibule and are released. Mhrcus (1941, 1942) discusses the release of state- blasts from Stolella evelinae, Stolella agilis, andigyalinella 'carvalhoi throughwa special pore, and Wiebach (1955) reports that he has observed the expulsion of statoblasts from living polypides in Plumatella.repens and.P1umatella emarginata. The author has not observed this process in living‘g. fruticosa colonies. Zooecia The zooecia of my specimens are typically narrow with the sides at a steep angle to the substrate. A keel is strongly developed on nearly all of the repent zooecia. This keel is often obscure to lacking on the free branches, which often are essentially round, in contrast to the triangular repent zooecia. Allman (1856) describes the keel as obscure. Braem (1890) describes the keel as mostly distinct. Toriumi (1954b) states that the keel varies from weak to strong and that the furrow is absent except in rare cases. A furrow is present on several of the zooecia from two of the Michigan collection sites. A specific character of'g. fruticosa is the formation of a linear series of daughter zooecia from the side of a mother zooecium. The daughter zooecia produced by this unique budding zone are detached from the mother zooecia and are thus believed to be a supplementary source for new colonies. How- ever, Wiebach (1954a, 1954b), after a month of observation, reports that no colonies were formed by these detached buds. After these daughter zooecia have been released, a charac- teristic serration (stumps of the daughter zooecia) is present on the mother zooecia. Jullien (1885) noted these unusual buds and serrations on Plumatella lucifugg,(includes‘£.‘££gg$- cosa). He found one zooecium with 12 daughter zooecial locations. One of the daughter zooecia was still attached. Wiebach (1954b; Fig. 2) portrays a portion of a coenecium on the zooecia of which as many as 15 or 14 bud stumps appear to be present. Toriumi (1954b) records that serrated branches are present on nearly all colonies which he collected. In contrast, serrated zooecia are present in colonies obtained from four of the ten Michigan collection sites. The maximum number of daughter zooecia stumps on a single zooecium.in the Michigan specimens is eight. Zooecia with daughter buds and characteristic serrations are shown in_Fig. 25 and 24. -75- “umai'ello. Q Yuth (030.. Zoesifizvggtgs S Penal 94.25. Moi—her Zooecium chh two (la htar zooecia. 5": [L attached (Se. tum ma 2. Seen as the dark Una at ‘Hie base iii-he upper do Light er as o 2.014,; Fury-L gelrm‘tiedi 1.3a; um ~ Show. WMCH do~ chr Zooecia. Mama be.‘ detached. —76— Ectocyst The Michigan specimens agree with the description Toriumi gives, in that they are occasionally slightly incrusted, otherwise they are without incrustation. The ectocyst is semi- opaque and pale grey or pale yellow-brown in color. m Allman (1856) does not refer to septation. Wiebach (1954a) refers to the septa which form in connection with the special daughter zooecia. Toriumi (1954b) states that a septum is present in each zooecium. —This is not the case with the Michigan specimens. Septa are frequent or present between most zooecia in six of the collections. However, septa are only occasional in colonies of three collections, and absent in two small colonies from the remaining collection site. The greatest number of septa are pale yellow-brown in color and have a thin vertical perforation. Some septa are nearly complete with only a minute central pore visible with a thin slit or a brownish suture extending from this pore to the substrate. Tentacles Jullien (1885) reports that Vaucher gave the tentacle numbers as between 25 and 52 in 1804. Jullien reports that they range in number from 42 to 54, with the most frequent number being 44. Toriumi states that the tentacles range in number from 52 to 50, and that 40.2 to 42.0 is the center of this range. The tentacle numbers of the Michigan specimens vary from 58 to 55 for 102 counts. The average tentacle -77- number is 45, thus essentially in agreement with both Jullien and Toriumi. Floatoblasts Relative to float coverage, the Michigan specimens agree with the statoblasts pictured by Allman (1856), Borg (1941), and Toriumi. The float covers the major portion of the more flattened dorsal surface, often leaving a slender area of exposed capsule (Fig. 25). There is a greater area of exposed capsule on the ventral surface. The average dimensions of the naked capsule are as follows: dorsal surface, 0.25 mm. by 0.07 mm.; ventral surface, 0.51 mm. by 0.15 mm. Statoblast measurements are given in Table 4. The data for the Michigan specimens agree with the data for specimens fran other parts of the world except in the capsule ratios. The capsules of the Michigan specimens tend to greater narrowness. Mammilo lations on the capsule surface are fine. The central portion of the capsule is sometimes smooth. Sessoblasts The dimensions of the Michigan §° fruticogg sessoblasts agree with those given by most other investigators. Wiebach (1954a) reports that he has found sessoblasts with a length to width ratio of more than 5:1. The lamella is wide in this species with.a distinct lacy reticulation, and it has a serrated border. The surface contour of the capsule is unique in that prominent tubercles protrude from the dorsal surface. These tubercles are irregular as Toriumi (1954b) reports, and they are more TABLE 4. Plumatella fruticosa measurements Source from which Hum-berm Whole statoblasts measurements were of Length Average Width Average Ratio taken measurements in run. length in m. width length to width Floatoblasts Present study 40 (0.44: 0.49 0.11; 0.20 1:2.45 0.65 0.22 Braem (1890) 0.50: 0.52 0.20: 0.21 1:2.48 0.67 0.21 Pateff (1924) ' 0.56 0.20 1:2.75 Lacourt (1951) 20.62: 0.20; 3 0.60 0.25 Toriumi (1942) 20.41: 0.17; } (Av. 2.36.2.40)‘ f Toriumi (1954a ‘o.4o; 0.41; 0.17: : 0.20 (Av. 2.36.2.40)‘ 0.55 0.48' 0.23 ; Sessoblasts ) i Present study 21 0.47: 0.60 0.19: 0.26 1:2.5 ' 0.71 0.50 Laeourt (1951) 0.70 0.27 1:2.53 Toriumi (19549 . * Toriumi gives his average as a range. therefore approximately with other averages. it can only be compared _79_ # ‘— “an.“ amwugmos\ .- -. ---— -....o— var”.- -- Number Capsule of Length Average Width Average Ratio measuremnts in mm. length in mm. width length to width 40 0.27: 0.52 0.08 0.15 1:2.26 0.3? 0.15 l i F '. 0.22: 0.153 0.27 0.17 0.27, 0030 0e14’ 0.16 1.50p1e69 0.35 ( 0.19 21 0033’ ‘ 0e44 Osl‘, 0019 132.31 0.50 E 0.20 t 0.393 0045} 0e17, 0e19, 2.31.2.59 0.56 0.49“ 0.21 _ 0.20‘ Fig 2.1. 5¢SSobia5T ~80- ?\uwxatella. f rid-1‘ c as 0., Fu‘15‘. F\eo:toblast d6r$a\ Suxfate. FicYZ‘; sessobLO 5‘- (Nofe rei—Cculafions 0n capSuLl e) . (€10le aired tubercles 9- $e_cn Clear). (“Oh Pen @4an e c apSule) fic‘ 18 —Scss°bla5t— av weaker Enter Meat 5 owin Ye’ciaulal‘ed lamellmdv't) ““034de hiberdes -81- elongate along the peripheral portions of the capsule. He also states that these tubercles "show specific character in number, distribution, shape and size." The tubercles on the Michigan sessoblasts (Fig. 26 through 28) appear to be particularly well developed in comparison to Toriumi's Fig. 4, No. 11. They are often bent or twisted and may sometimes be seen to extend out over the lamella. These tubercles are seen greatly enlarged in the photomicrograph, Fig. 28. ‘gyalinella orbisperma (Kellicott) 1882 New Designation Colony The colony architecture of this species is variable. The Barry County specimens are dendritic with repeated dichotomous branching, and the branches are longer and more sinuous than in other filglinella specimens I have collected. In addition, the Barry County colonies are often free of the substrate or only loosely attached to it or to clumps of algae, moss, or detritus. The zooecia, in the basal area of a colony, are frequently intertwined. Colonies collected in this county are luxuriant and irregular in aspect (Fig. 29). The specimens from Otsego and Iosco Counties are more compact and lack free branches (Fig. 50). The polypides in the Barry County colonies are arranged in distinct clusters of four to eight individuals. In speci- mens obtained from two other counties, the polypide groups generally include somewhat fewer individuals. The groups in a linear sequence incline, alternately, in opposite directions (i.e., one group leans to the right, and the next group leans Via) 2.9 Co‘onyo otHyalfnella. o_r__b\‘spe_rmo_ -QV°W‘ rn' Coun (nuke circular Si-cAobkasts \‘n Con; cal Zooeo‘so.) 9?.)- -3°. Colon 70+ fludlindlk orbis 8mm, {3mm \fljoseo Gourd (7.008030. Less elongate. ‘Haun in F123. 29) to the left in sequence). Except for this slight lateral inclination, individuals in a cluster are essentially vertical. Only terminal groups are inclined forward at approximately a 45 degree angle to the substrate. The polypide groups are connected by a basal extension of the proximal zooecium in each group. This zooecial extension resembles the pseudostolon characteristic of the genus Stolella. The elongated zooecium is well developed in the Barry and Iosco County specimens; thus, the separated clusters of polypides are readily apparent. The connecting zooecium.is not so elongate in the Otsego County specimens. Except for the elongation of the zooecium of the proximal polypide, successively budded individuals in a group remain contiguous (i.e., their zooecia do not elongate, so they remain in linear sequence, conjoined to the individual from which they were budded). Often the individual zooecia in a group project out from the basal gelatinous matrix of the colony in the form of elongated cones. This is most evident in the Barry County specimens (Fig. 51). The Iosco form has short conical projections, whereas the surface of the Otsego form.is nearly flat, as the zooecial tips do not (or rarely) project above the level of the swollen coenecium. The colonies discovered in the latter two counties have a growth form similar to_§yalinella punctata. Otsego and Barry County speci- mens appear to represent two extremes of colony form, while the Iosco specimens are intermediate. -84- Kellicott (1882) states that the branches of Plumatella (Hyalinella) orbisperma appear to remain distinct and very dense. The polypides are distinct yet compact, with the coenecium extending to the right and left of the point of origin in two or three ”slightly radiating, sparingly branched, trunks." He states further that the polypides are somewhat in clusters and often opposite. The recently collected speci— mens conform in general, to Kellicott's brief description. The polypides have deeply indented lophophores and a large epistome, often faintly brown at the base. Zooecia The zooecial tips are flat and obscure, or round, or short and elongate cones. Only the proximal zooecium of a group is much elongated. The zooecial diameter varies fran 0.6 mm. to 2.45 mm., while the zooecia of the Barry County specimens are rarely wider than 1.4 mm. The zooecium is thickest in the Otsego and Iosco County specimens. Ectocyst The ectocyst is gelatin-soft and hyaline. The thickness of the ectocyst is highly variable. Kellicott (1882) states that in his form the ectocyst is not so thick as in Plumatella vitrea (synonym of Hyalinella pgnctata). The ectocyst is not incrusted.and only in the Otsego County specimens are lamellations visible in the orifice region of the zooecia. Agglutination of zooecial ectocysts is frequent in the dense repent specimens, but not so frequent even in the intertwining branches of the Barry County Coenecia. —85- £92.22 Septa are lacking. The polypides upon retraction actually come into physical contact, the zooecia being confluent. Tgntacles Tentacle numbers (maxima, minima, and averages) are given in Table 5. The maximum number, 67, was recorded several times for the Barry County polypides. The minimum number of 47 was recorded for a young colony with only two polypides. The average number of tentacles for polypides counted during the present study is 60.5. This number coincides perfectly with the number of 60 given by Kellicott for Plumatella (Hzalinella) orbisperma. Statoblasts Only the floatoblast is present. Colonies from.Barry County were observed for four years, summer and fall, and sessoblasts were not found. The floatoblasts are nearly round (Fig. 52 and 55). The ratio of length to width varies from 1:1.01 to 1:1.22 (Table 5). Only one of the measured stato- blasts has a ratio of 1:1.22. All others have ratios of 1:1.17 or below. Kellicott (1882) states that the statoblasts of Plumatella (Hyalinella)gggbisperma are nearly circular, 0.520 mm.‘by 0.545 mm., and that the greatest variation between length and width was 0.525 mm. by 0.560 mm. These length and width figures give Kellicott's statoblasts a ratio variation 1:1.08. The statoblasts are almost equally convex on both faces, again in agreement with Kellicott's description. The peak of the ventral capsular convexity is somewhat pointed in v _86.. TABLE 5. Eyelinella orbisperma and gyalinella punctata measurements. Source fromehich . Whole statoblast measurements were lumber Length Average ‘flidth. Average 'Ratio taken of in mm. length in mm. 'width length to width measurements +--- A ‘4 _ a .. _ a“- Hyalinella orbisperma Present study 156 0.50: 0.54 0.28: 0.51 l:l.01:l:l.22 0.57 0.55 . Av. 1:1.08 Kellicott (1882) 0.54 0.52 (Av. 181.07 Hyalinella pggctata Present study 84 0.54: 0.59 0.55: 0.58 1:1.55 0.61 0.40 Kraepelin (1887) .0.40: : l:l.2:l:1.5 Annandale (1910 } Vorstman (1928) .. 1 ; var. 33353 i T 0.55 i 0.25 f 131.3 var. rostata v 0.60 3 2:1 Rogick (1530) ( 56 0.49; 0.54 i 0.55; 0.57 Av. 1.46 . = 0.60 0.45 Lacourt (1951) i ‘ large form. 1 0.43: l 0.28; . 0.46 0.50 small form . 0.50 0.25: E ) 0e30 roam (19551) 1 0.37; 0.42; 0.28: 0.30; 1.24:1.56 ; 0.49 0.44: 0.34 0.51. * Toriumi gives his average as a range. Therefore it can only be compared approximately with other averages. _87_ Number #CapsufilfiL ____ Tentacle .- of Length Average Width Average Ratio numbers measurements in mm. in run. length to width _ “in--- i a- _-- 1-)- -_ H - ._-- _ 156 0.25; 0.28 0.23; 0.26 (Av. 1.07) 48,67 0.34 0.52 (Av. 60.3) r 84 0.59: , 0.40 0.28: - 0.29 1:1.58 ! 46.65 0.41 ‘g 0.50 3 (Av. 57) 9 40.60 50.40 1 ‘ 28 50 56 0.51; 0.55 0.25: 0.27 1.50 55.55 0.40 E 0.51 ~ i i i 0.27: 0.50: 0.22: 0.24: 1.15.1.41 £ 42.58 0e34 Os31‘I ‘ 0.7.7 oe25’ (A's 1e26, _,. -————-—-——-- ' - £029)..- L -88.. (iqqlineua Orbis perm CL 973.32.. igufsuubust L Surface H.151. Clo afed zooecium w; reunded Hp my. 33.7..112. sanctum- C E‘reater en lavc)e men/rt) -89- contrast to the rounded dorsal convexity. The float is narrow on both the dorsal and the ventral sides of the statoblasts of Hyalinella orbisperma. The following are the average lengths and widths of the naked capsule: dorsal side, 0.225 mm. and 0.215 mm.; ventral side, 0.25 mm. and 0.24 mm. .3: orbisperma (includes Plumatella orbisperma) and Stephanella hina (Oka,l908; Toriumi, 1955b) are the only forms with circular statoblasts, and the measure- ments and appearance of the statoblasts of the two agree in genmnfl. However, Gka's drawing (Plate x, fig. 5) of a stato- blast of S, blag shows more dorsal float coverage than is present in g. orbisperma. He states however that the width of the float varies rather markedly while the size of the statoblast remains more constant. Fine mammillations cover both the dorsal and ventral capsules of the statoblasts of '3. orbisperma, and their periphery is entire. The coenecia of colonies of H. orbisperma were frequently filled with statoblasts in August and September. I have only seen a comparable concentration of statoblasts in colonies of‘fi. repens. Diagnostic Discussion The colonies collected during the present study agree with the characteristics recorded by Kellicott (1882) in his brief description of Plumatella orbigperma. The taxonomic position of‘fi. orbigperma has been uncertain for nearly 80 years. Rogick and Van der Schalie (1950) mention the need for a clarification of the status of this specieg and the infor- -90.. mation acquired during the present study makes a taxonomic revision of this form necessary. The species must be placed in the genus gyalinella. A revision is dictated by the following characteristics: polypidesoften in groups; swollen or inflated ectocyst; ectocyst always without incrustation; absence of septa between polypides and groups of polypides; hyaline and non-sclerotized ectocyst; propensity for contiguous ectocysts to agglutinate; absence of the sessoblast. 'gyggg- ‘ggllg repens often lacks septation, but the other characters are not in agreement with‘g. repens characters. Another form with which Hzglinella orbisperma might be compared is Stepha- ‘ggllg‘higg. As already stated, the circular floatoblasts are what make this comparison appealing. Also the ectocyst is thick and hyaline as in‘g.‘§igg. However, the ectocyst in §_. 11.3-11.9. is very soft, and this species has a more clearly defined stolen-like region than does‘g. orbisperma. The poly- pides are single vertical buds not forming the budding clusters in the same manner as‘g.‘ggbisperma. Also the tentacles of §_. 2.1.29. number only 28 to 46. Finally, 51. £2.39; produces sessoblasts. Gelatinella toanensis (Toriumi, 1955s) has an irregular nodular colony form and has elongate conical zooecia. These characteristics are manifest in the Barry County speci- mens, however, the typical polypide clusters are lacking in this form. In addition the elongated statoblast with the capsular appendage and the presence of the sessoblast discourage further systematic comparison with the Michigan specimens. The evidence thus strongly favors placing the orbisperma form ._ 91- in the genus Hyalinella. The free or open branches of the Michigan specimens sometimes resemble the branches of Toriumi's (1955c) Hyalinella minuta. However, the low tentacle numbers, the oval floatoblast, and the clavate zooecia of his form are not found in may specimens. The most difficult consideration regarding Hyglinella orbisperma was whether it should retain full species status, or whether it should be combined with‘gyalinella'punctata. The statoblast has received particular emphasis in freshrwater bryozoan taxonomy, and‘g. orbisperma varies from‘g. punctata chiefly with regard to the statdblast. The Michigan‘g. ggnctatg statoblasts are large. However, other investigators, as Kraepelin (1887) and more recently Lacourt (1951), have found both large and small statoblasts in H. gnctata colonies. Lacourt found two sizes of statoblasts in the same colony. However, whether large or small, the shape of the §h_punctata statoblast disagrees with that of'§._ggbisperma (Table 5). Statoblasts of H. punctata are broadly oval to elongate oval in shape, while those of‘g. orbigperma range from circular to nearly circular in form. Kraepelin's (1887) Plumatella pgnctata var. 33235 has bigger and broader statoblasts, while his smaller var. prostrata is narrower. Vorstman's data are contrary to Kraepelin's, showing the larger var. prostrata form as being narrower in proportion than the var. densa statoblasts. Vorstman (1928a) and Toriumi (l955d) both mention the serrated peripheral margin on.§. punctata which is essentially lacking 92 on the statoblast of the orbisperma form. Viewed from the side, the statoblasts of‘g. orbisperma are approximately equally convex, with the ventral capsule somewhat pointed. Toriumi's (l955d, Fig. 5) illustration of the side view of‘g. punctata statoblasts shows nearly equal convexity of the dorsal and ventral valves, but the capsules are not as greatly inflated and the ventral side lacks the pointedness of the statoblasts of g. orbisperma. The Michigan fl. punctata statoblasts are somewhat more flattened on the dorsal surface and lack the pointed ventral capsule. Rogick (1940; Plate II, Fig. 6-8) shows a typical statoblast of .§.:ggnctata with.a decidedly flattened dorsal surface. Her figures and illustrations.indicate a wide coverage of the capsule by the float, particularly on the dorsal side. Such extensive float coverage is found in the statoblasts of the Michigan H5 punctata colonies. Thus there is proportionately much less total float area on the statoblasts of‘g. orbisperma. Toriumi (l955d; Fig. 5) shows less float coverage of 31. mg- 2232 statoblasts than is evident in American, European (Kraepelin, 1887), or Javanese (Vorstman, 1928a) specimens. 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T. u n. t u n. w. u w w w n. w I w w w s w $25388 . .. 33a. mu 7. (continual) 4.39- «anon 'IIOIOQI WWW ‘II9I048 1: F944“ unopodoqdoq 2 opoomn E'T "Fawn-IO A J :: ”unfit ‘1101‘UVQOOJ autumn.“ A utoonmtu E 3 N mm“ A “f 1 “100140904“ 219362 moduqu 'IIO‘III‘KH :: :2 34an VIINII‘KH C mania» "IIQWIJ 22G sooogqna; 1 ‘Itflmtd I: I4 :4 nod” T T ”1104mm :: 5&3 O a 1: ad «a .2. 5 5 a a 3. 3 ~ . « '..:33 '"§§§§ °§§§§§ §°:.a» < mama €1.40- with.the-sponge‘ygzggig.mulleri. Stentor cgeraleag and hydroids of Qraspgdacusta sowerbzi were attached at the base of the zooecia and.sponge, and [orticella sp. and Vaginicola sp. were abundant on the ectocyst of the bryozoan. Sponges were found in association with Bryozoa at 29 of the 122 collection sites or at nearly 24 per cent of them. This frequency of association does not indicate that the dis- tributional relationship between the two phylais more than accidental. Plumatella repens was found at nearly every collection site where sponges were collected but was seen interpene- trating sponges only four times, on one occasion the rela- tively rare Heterongnia repens. .20 sultana and‘g,‘ggggr ginata were discovered in intimate association with sponges eight times and four times respectively; Eight of the 10 associations of 2, emarginata with sponges were recorded for streams and on six of these occasions the sponges were §pongilla fragilis and Hezenia mulleri. ‘Ezalinella‘gggigy m was found in intimate association with §_. fragilis. Perhaps, the most provocative relationship was that of Plumatella fruticosa with Tubella pennsylvanica. The sponge was collected twice and.both times entangled with the bryozoan. Both of these associations were made in deeply colored, acidic water. Jewell (1935) reports that Tubella pennszlvanica is found frequently in water of this type. The occurrence of‘g. fruticosa in such water has already~ been discussed. -141- Other investigators have reported on bryozoan-sponge ’ associations. For example, Potts (1884) found Paludicella (Pottsiella) erecta interpenetrating a species of mezpnia. Vangel (1894) claims that E. sultana was most frequently associated with §_. fragilis and g. laoustris. Despax (1926) reports on a close association between Plumatella repens and §_. lacustris; Tanner (1932), an association of E. sultana with g. lacustris; and Borg (1941), the frequent intimacy of E. sultana and Ephzdatia (Megnia) mllcri. I Table 8 summarizes the frequency of occurrence of the species of EctoprOcta with each other. Plumatella _e_m_ar_- gi_n_a£a_ occurred in the same river or lake with 2. repens 12 times and with Paludicella articulata 11 times. In pro- portion to the number of times each species was collected, 2. articulata occurred more frequently with z. repens and _11. emarginata than either of these did with each other. This suggests a wide adaptability by 2. articulata. It also suggests an ecological basis for the separation of the closely intergrading 3. refine and _11. emarginata. The two species were, however, observed in close association on two or three occasions during the present study. 'Cunnington (1920) found them together in three African lakes. Other records exist of their occurrence together. 2.. sultana was collected at 25 more lakes and streams than £0 articulata, but it occurs with E. emarginata approximately the same mmber of times as does _1_’_. articulata. These records, all taken together, suggest that g. emarginata may tend to occur IABLB 8. Showing the frequency of association of the species of ~142- Iichigan.lct0procts collected. ‘ b I 3. v 3 E ‘3 s . '".3 :3 a -3 3. .a .a .4 a (u e 3 <0 v! a; . ‘3 i: a. :3 a g “H °,: 3 1° cw! a a? 3 H H “.1 éaaiest °:a: .E 3 pee " 4. c. e n o ca e a i e «a e a a? a: a: a? u? a: at” a! o' a" v; a; 83 P. repens -- 6 12 3 3 49 51 3 19 1 1 l 10 P. fruticosa 6 -- l 1 -- 2 2 - 3 .. -- -- 30 P. emarginata 12 l - 2 l 12 ll 5 3 l 1 1 5 H. punctata 3 1 2 -- -- 3 4 1 2 -- -- -- 3 H. orbi.pm 3 .- 1 -- -" 1 1 -C -- .- ..- -- 69 P. sultana 49 2 12 3 l - 25 3 14 1 l 1 44 P. articulata 31 2 11 4 l 25 - 4 l5 -- -- ~- 6 P. magnifies 3 -- 3 1 -- 3 4 -- 2 -- -— ~- 22 C. mucedo l9 5 3 2 -- 14 15 2 -- 1 l 1 1 L. carteri 1 -- l -- -- 1 -- -- 1 -- 1 1 1 8. indies l - 1 -— -- l -- -- l l -- 1 1 8. evelinae l - 1 -- -- 1 -- -- 1 1 l -- -143- more often with g. articulata than with any other species. _P_. articulata and §.sultana were found with _11. refine with approximately the same frequency. However, 2. articu- lata and g. sultana were intimately associated together on 13 occasions, and 2. repens was not found intimately asso- ciated with either of them more than two times. Thus, even though there is little difference among these three species with- respect to the number of mutual occurrences, there is a decided indication that E. sultana and z. articulata have an affinity for a similar microhabitat. This contention is supported by the additional observation that many of the most luxuriant growths of the two species collected during this study were obtained from eight of the 13 sites where they were intimately associated. Evidence of a similar ecology for Particulate and g. sultana is provided by earlier investigators. Wesenberg-Lund (1907) reports that they are commonly found entwined in the lakes of Scandinavia and Greenland. Harmer (1913) records the occurrence of 2. articulata and E. sultana, along with Plumatella fungosa and 2. emarginata in British waterworks. Annandale (1922) reports only 2. articulata from the waterworks of Japan. Harrell (1927) states that the two species are associated more frequently than not, and Berg (1941) fmnd _F_'. sultana frequently associated with 2. articulata on the underside of stones, but sometimes Plumatella fruticosa was found with _E. sultana. -144- Plumatella fruticosa, on the basis of only 10 collections, appears to be somewhat more exclusive than other forms. It was the only species collected in four bodies of water, and it was found in each of the other six collection areas with 2. repens. However, 2. fruticosa wasnever found closely associated with any species of Bryozoa with the possible exception of gzalinella punctata and z. articulata. These three forms were removed from large dead tree stumps, which were situated in the organic cone in a bay of Gull Lake. Fredericella sultana was discovered in one of the most unusual associations ever reported. A small colony of this bryozoan (Fig. 45) was attached to the dorsum of a live Odonata larva, Libellula commanche. The small colony had produced two sessoblasts. V Predation: leidy (1851c!) saw) Plumatella diffuse (emarginata) colonies being attacked by larvae of Hydrophilus. Harcus (1926) observed gldrozetgg lacustris, an oribatid mite, eating Cristatella mcedo statoblasts and colonies. He asserts that Dendrocoelum and PolEelis eat living Bryozoa, and that Tendipedidae eat both polypides and statoblasts and are congregated in large numbers in and around the coenecia. He suggests that this "biocoenose" must be an in- direct source of nutrition for fish. Brooks (1929) reports that flatworms eat young Pectinatella magnifies colonies. Marcus (1934) states that additional enemies of Lophopus matallinus, are snails, Trichoptera larvae, and Oligo- chaeta (eg., Chaetogaster sp. and £9.11. Josinae). Rusehe (1938) Fx‘q. 4'5“- Frederiaellm Sultana coLon attached +0 dorsuw. 0 ohofico. \awm, L. bellula. commanche. Ff -¢b- TrichoP‘i‘evnn ease Conn 394 \Cur e\ o Lp kopodeliai ecu'bevi stile la ts—TP -146- 6 declares that tendipedids decimate Plumatella fungosa poly- pides. Tendipedids were frequently found, often in abundance, with Bryozoa collected during the present study. Some were living or eating in the empty zooecia, and others were seen brewsing the surface of the zooecia eating mostly vegetable matter. In some cases profuse growths of Bryozoa and equally douse populations of tendipedids covered a portion of the substrate. The larvae lived in cases which lay parallel to and filled up the spaces between zooecia. Tendipedids would sometimes bite at the surface of the ectocyst but only rarely would they damage it. Even when they did, they have been seen to leave the damaged area. Thus the majority did not appear interested in the Bryozoa, but rather in the or- ganic material adherent to the zooecia, or in other small animals. Sometimes portions of bryozoan fecal pellets were eaten by the midge larvae. In several collections where dense populations of both animals lived in close association, essentially all of the polypides were healthy and evaginated. These communities suggested.mutualism.rather than predation. Peloplinae were often seen moving across a colony and feed- ing,’but on only one occasion did the writer see what could be termed an attack on a polypide of Plumatella emarginata. The larva took hold of the lophophore, but finally released its hold and in doing so pulled off three tentacles. Ten- tacles were frequently missing presumably as a result of predation. ‘Whether or not tendipedids, often found living -147- or eating in the zooecia, were primarily predators or sca- vengers was not determined. Perhaps fewer species of tendi- pedids are predacious on Bryozoa in this part of the world than in places from which high predation has been reported. An Elmidae larva attacked two polypides. (he polypide survived and there was some uncertainty regarding the dis- posal of the other polypide. when the larva departed, the polypide looked essentially uneaten. Several Helichus lithophilus larvae were observed inside the zooecia of what appeared to be a deteriorating colony of Plumatella _e_m_a_r_- ginata. These larvae may have been scavengers.) A Lmaea sp. killed and partially ingested two polypides-of a film-- ‘_1_:_e_l.._1.._a m colony, and _Hglisoma trivolvis injured several polypides in moving across a g. repens colony. Whole state-- blasts and parts of statoblasts were found in the excreta of _H. trivolvis. ‘ A portion of a Cristatella 'mcedo colony and three or four statoblasts were found in the stomachs of two specimens of. M flavescens‘ from Wintergreen Lake. Twenty-seven of the fishtmd been netted by a class in Ichthyology and given tougthe (author for examination. Trichoptera were unquestionably the most carnivorous predators of Bryozoa found during this investigation. Several different species were seen attacking polypides. The most frequent predation, observed repeatedly on colonies of Plumatella repens from Wintergreen Lake and Burke Lake, was caused by Athripsodes sp. in the family _Hldroptilidae, -148-. and‘by Orthotrichia sp. in the family Leptoceridae. Athrip~ .ggggg‘sp. either attacks the evaginated polypide or with un- intended sagacity eats a hole in the zooecium.and devours portions of the polypide commencing with the proximal or stomach region. Often Athripsodes sp. eats a portion of a statoblast, and then proceeds to another zooecium. Orthotrichia sp., a relatively small and rare tricop-, teran, was perhaps the most savage predator observed. The (larva would very rapidly grasp an evaginated polypide, and then thrash about rather forcibly in order to gain a hold with it's mouthparts. This characteristic attack was followed by an equally consistent period of ingestion. The time re- quired for the complete predation of one polypide of.§. repens by Orthotrichia sp. was 33 minutes. The polypide was alive for 15 minutes after the initial attack, and several violent contractions of the digestive tract occurred during this period. The trichopteran never moved its body while ingesting the polypide. First the tentacles, lopho- phore, and pharyngeal region were eaten: then the polypide was drawn progressively farther out of the zooecium by the insect. When the tricopteran departed, the lower portion of the caecum.and the funiculus were all that remained of the polypide. Trichopteran larvae frequently adorn their cases with statoblasts. A larval case composed almost wholly of‘ggphg- podella carteri statoblasts is shown in Fig. 46. 1. 3. 4. 5. SUMMARY A distribution map showing the species of Bryozoa recorded in.each.county was prepared. Collections were made in 122 bodies of water. The map includes Bryozoa repcrted by earlier investigators. Three species of Ectoprocta not previously recorded in Michigan were found. They are Lophopodella carteri, Plumatella fruticosa, and Stolella evelinae. 2, £52217 .2252 was found in 10 localities. (Plumatella orbisperma, reported only once previously, was found and is assigned to the genus glalinella. The new designation is;§1§linella orbigperma OKellicott) 1882. i A discussion of the'ariability'and.systematics of the species found in Michigan includes comparisons with worldwide forms. Attention is concentrated on Elana: 15.922. repens and Plumatella emarginata. A variant form (the Pony Creek form) is disucssed, and assigned to;§. emarginata. It has characteristics consistently inter- mediate‘between g, emarginata and.§. repens, and shares characteristics with Plumatella elegans and Plumatella avanica. Both flabelliform mud geminate-flabelliform colonies of E, emarginata were found. Evidence is presented to demonstrate that this growth form.may be the result of a simultaneous germination (with the subsequent loss of the valves) of two contiguous floatoblasts. -149- 6. 7. 8. 9. 10. 11. -150- Fredericella sultana appears to be more tolerant of con- ditions in marl lakes than other species. .11. repens was found most often in lakes, ponds, and ditches, than in streams as were‘gyalinella‘punctata andlgzglinella orbisperma. ‘3. emarginata demonstrated a decided preference for streams or moving water. ‘flgyg- dicella articulata demonstrates an adaptability to flow- ing, roily and still water. 'New tolerance limits for temperature are given. Living colonies of Federicella sultana were collected during the winter months in water with a temperature of 1.5 de- grees centigrade. Living colonies of 2, repens and Plumatella fruticoaa were collected in water with a tem- perature of 37 degrees centigrade. Plumatella fruticoaa was found in water with.more color and a lower pH, than were the other forms. Tables listing plants and animals associated with Bryozoa are given. Particular attention is given to sponge- bryozoan and intra-bryozoan associations. Predators of Michigan Bryozoa were snails, Tendipedidae (infrequently), Elmidae and‘ggggg flavescena (at least indirectly). However Trichoptera were the most frequent predators. Athripsodes sp. and Orthotrichia sp. were seen repeatedly attacking and eating polypides and stato- blasts of Plumatella repens. PART II GROWTH, I'JOR'I'ALI‘JJSI, AZTD chtem ITY OF PLI'JILATQLLA 13131312173 GRG‘ITH, MORTALITY, AND LONGEVITY OF PLUMATELLA REPENS INTRODUCTION Studies on the growth, mortality, and longevity of invertebrate animals have been few. In the Ectoprocta, for example, information on growth dynamics is scarce, and com- pletely lacking for most species. Among the fresh-water Ectoprocta, most growth and longevity data have been obtained from laboratory-reared animals. Data for animals living under natural conditions in lakes, ponds, and‘streams are essentially non-existent. This investigationwasnade in an attempt to obtain such information. The data were all I collected in the field. Parallel studies on growth, longevity, and mortality were conducted on two Michigan Lakes, Winter- green Lake in Kalamazoo County and Burke Lake in Clinton County. Numerous colonies as well as individual polypides were marked and observed at regular intervals, and data were recorded during these observation periods. This research was conducted in the spring, sunmer, and‘fall of 1959 and during the spring and the summer of 1960. The investigation was conducted on Plumatella remns, believed by many bryosoologists to be the most common and cosmopolitan species of fresh-water Ectoprocta in the world. No comparable field or laboratory research has been conducted on this organism. _P. repens thus appeared to be a particu- larly desirable animal for such a study. The most comprehensive growth data are those acquired- by Rogick (19456), in a laboratory study on colonies of -151- -152- _H‘valinella mnctata. This species and Plumatella repens are considered by most investigators to be closely related, and they are both in the family Plumatellidae. Rogick (1938, 19453) gives some information on the longevity of g. punctata and Lophopodella carteri. The data of the present study indicate that growth tends to be geometric in _P_. repens under favorable conditions. There was, however, much variation in growth rate. Individual polypides of _11. repens rarely live longer than six weeks. Mortality varied considerably with respect to site. The total predation on both large and small ectoproct colonies was extensive suggesting that these animals are perhaps more significant prey organisms than has previously been suspected. Wintergreen Lake In 1926, W. K. Kellogg of Battle Creek, Michigan, pur- chased the SOC-acre farm which surrounds Wintergreen Lake. The lake was established as a sanctuary for waterfowl. In 1929, Mr. Kellogg gave both the farm and sanctuary to Michi- gan State University for agricultural experimentation and scientific investigation. Wintergreen Lake is located in Tier 1 south, Range 9 west, Section 8 of Ross Township, Kalamazoo County, Michigan. Fetterolf (1952) states that the lake had an area of 39.99 acres, a mean depth of 7.56 feet, and maximum depth of 21.33 feet. There were no permanent feeder streams. At the south end there was an outlet emptying into Yale Lake, one-half mile away. Springs at the north and northeast shores help ~153- to maintain the water level. Wintergreen Lake is one of many small pit lakes in the Kalamazoo-Mississianawa morainic out-wash plain system. Fetterolf (1952) states: Bottom deposits are variable. The south and west shore is (generally) pulpy peat to a depth.of three feet, where marl becomes intermixed with it. Marl is pre- dominant to a depth of about twelve feet in all other parts of the lake except the east and northeast shore. These shores are exposed to wave and wind action and are sandy to a depth of 2.5 feet where marl again becomes predominant. Beyond the twelve-feet depth the bottom is of a fine organic case. He continues: Chara is dominant in the shallow areas of the lake. As the depth increases, two species of Potamo eton become abundant: Sago pondweed, Potamo eton pecEI- ngtns, and leafy pendweed, Potamogeton IoIIosus. Coontail, Ceratophyllum.demersum, andTbushy'pondweed, Na as flexIIis, combine 'with the potamogetons to g ve dense weed bed extending to about the four meter contour. Beds of spatterdock, Nu har advena, occur along the shore in the southwestern Eafl' of the lake. There are two patches in the northeastern half; one in the eastern corner and another in the northwestern corner. White water lily, N haea (Castalia_of authors) odorata, is limited go the lagoon area at the southern EIp. The shoreline egetation consists predominately of two species: Swamp loosestrife or water willow Decodon verticillatus var. 1aevigatus, and button busE, CephaIanEEEs ochdentalIs. Fetterolf further states: This lake is perhaps one of the richest in the country from the standpoint of the nutrients added by natural fertilization. Each fall fran 6,000 to 10,000 Canadian geese use the sanctuary as a stepping over place on their southward.migration. ‘An equal number of ducks are also present at this time and a flock of about 70 swans, geese and ducks use the lake the year around. The extent to which the tremendous amount of natural fertilizer in their droppings improves the environment for fish production is unknown. However sokolowski (1960) states that the swan, by feeding on vegetation, prevents the development of stagnant conditions. He maintains that the swan's "abundant droppings falling -154- into the water favour the development of vegetative and animal plankton." Burke Lake Burke Lake is located in Tier 5 north, Range 1 west, Section 23, of Bath Township, Clinton County, Kichigan. The lake is in the Grand River drainage system and has an area of 1.8 acres. Roelofs (1941) states that there were no inlets or outlets of appreciable size, although a small out- let existed .at the north end of the lake. The lake had a maximum depth of 39 feet, and very little shoal area, as the bottom drops off rapidly. The lake was surrounded by a "quaking bog”. Roelofs wrote that the bottom was essentially marl with some organic content in the shoal area. In the deeper areas he asserts that the bottom was marl and fibrous pest and had a 15 to 20 feet layer of organic material. The most comon water plants in the outlet were Cerato- phzllum, M sp., £3133 flexilis, Potamogeton gametifolius, Nuphar variegatum and m latifolia. Roelofs gives One reading, 175 ppm., for bicarbonates. He reports a pH varia- tion of from 6.8 to 8.5. The author found the pH to vary from 7.4 to 8.5. Burke Lake is surrounded by trees and shrubs with tama- rack prominent, particularly along the entrance to the out- 1et where the majority of Plumatella repens study stations were located. The physical characteristics and the vegeta- tion of the shallow marginal areas of the lake and in the -155- mtlet were at the time of this study, generally, in agree- ment with information given by Roelofs. METHODS The data on growth, mortality, and longevity were gathered at regular intervals from mmerous colonies of Plumtella La- 2513 located at several different stations on Wintergreen Lake. in Kalamazoo County, and on Burke Lake in Clinton County, Michigan. These lakes, and stations on these lakes, are shown in Fig. 4'? to 53. Many of the colonies chosen for study in the spring consisted of one or two polypides de- rived from newly germinated statoblasts. A number of the colonies selected for study in 1959 and 1960 consisted of more than two polypides. In choosing colonies, it was necessary to examine a num- ber of substrates at several different sites on the lakes. The criteria for favorable sites were the availability of colonies at the site, suitability of substrates for marking,snc] permanency and structural integrity of substrates. The most favorable substrates were logs or planks semi-anchored along the shore line. liost stations on mrke' Lake were logs or floating posts, while most of them on Wintergreen Lake were flat planks. Tables 9 and 10 give information on the sta- tions established on Burke Lake and Wintergreen Lake res- pectively. There was some contrast in the environment among the different stations. Harkgg: The colonies chosen in hese studies‘were marked with the tips of plastic toothpicks. With a blunt dissect— ing probe, a boring was made in the substrate 2 mm. to 6 mm. to the right of a newly germinated statoblast. The right -156«- -157- . r 5.. 2:; if an? 2%. t2; 1%; . euro); (:30. 305650 c:. Jefekzm $56 8 04¢, weewom «exec... 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V028. .26 38332, .658 in 359: 1 2r... from 713 3 vmsarvo W0 :76, ”no, . wumcoaoo siser woo/o 30% ¢w§§flrnmm mflflz 59:00 .36 nwsucab .Er; ‘Tvcam «163 #soSW NH 00.:30u .ww . . (ESST veer T13 26%. Esaco/ao‘uiyr. .am «1&de $0560 .BW «0505.6 was/am, rfisow TB «163 HH 101001 (33 :2; “a“..“umow «godwprswflwwfi (SECOUOAEAM 0961 be: 500 .36 Maser: N Tflsdm U433 QWHSSO OH T . v0 AF. 371100..ch . {HMO . auofivr .w»oxw+.o,m¥§%> SESUOMZMJQMM Uvoxw Sigom «9..ch rfizdw 1.33 TATE r -SUUS. ”flaw “m WWW.” 05050 Swiom .3333 N Tchm. 1:01 V0.3: ,w bu 7:0 00 VS. wt: 0 dfiwfljw ov CODHJU> m 3+30nu..+w.c_dru$d;wfl!z NJ... via Cowyavoru> 71.30, 13 Rogue vary Eoibm Owermpjm :03on Aves; _foou .OH .306: —160- ' 4'? - . Fiafl'l- Sfa‘h‘ovx7 Burke Lake, Qh‘vfi-on Ocuvfi- Siafi‘ons «(4., \f “ I. .\I '1}, _"x 3{\ J" “u ‘H w - 45-3., 3“». ‘8‘“! ,. Fifi. ‘lrb. Sfaiu‘on 9, Burke Lake, Uin‘t‘on Cuuvfix’ -16l- CM)- '50. Sinkons 4-1, Burke Lake. (‘h‘vd'on 00- -162- “3.51. Std-{ans (a an& Qb- Nn‘nhv-rjreen Lakt, Kalamazoo Cow‘lxl. -- " ti“ > L"‘- ~ “'. I I. .‘ _. 4.1,." ~‘ . 3“." FCC}. 52. Starh‘ona ,WM‘Rr ream Lake, kalnmzoo Counw -165- ¥€cr55. Shfimns 10-13, Wini-cnjrgen Lake kaiamzoo Cbun+y -164- side of the statoblast was determined from the direction of germination. After the‘boring‘was made, the tapered tip of one-half of a toothpick was pressed firmly into the hole with the thumb. From two to 28 colonies were designated in this fashion at each of a number of stations on the lakes. Often all six toothpick colors - red, blue, green, yellow, white, .and pink - were used to designate colonies at a given sta- tion. Colored plastic pegs marking colonies on two sub- strates are shown in Fig. 54 and 55. When numerous colonies were chosen on one substrate, several series of colonies were marked (e.g., a yellow series, Ybl, 132, YBS, YB4; a red series, R-l, R-z,‘R-3, R-4, R-S). Each substrate was divided arbitrarily into a proximal and distal end. This designation was made with respect to a structural peculiarity or an artificial marker or tag placed at one end of the substrate. The criteria for the distal and proximal ends were noted on the field data sheets. The designation of proximal and distal ends made a color series possible (e.g., the yellow peg nearest the proximal end was designated Y-l). In some uses colonies were de- signated by two pegs often of different colors. Sometimes pegs were broken off, presumably by fish or turtles. Small fish were occasionally observed snapping at them. In most cases the broken tip was still imbedded in the substrate so that a new peg could be inserted next to the brdken one. Rarely'was a marker completely pulled and a color series discontinued. The peg pattern of heavily -165b marked substrates was mapped on a field sheet, which made it possible to locate a missing peg withouthaving to remove an entire color sequence. x The method of marking so far described was satisfactory for designating entire colonies for obtaining data on growth and.mortality; but for data on longevity, specific indivi- duals had to be marked. These individuals were often in colonies other than those hing followed for growth data. When a polypide was observed for longevity, a marking peg was placed beside that individual. For longevity study, termi- nal individuals were chosen (i.e., newly budded polypides), and pegs were then placed to the right of them. On substrates where colonies were also being fellowed for growth and gross mortality data, one color of peg (e.g., white) was used to designate individuals for the longevity study only. Thus terminal individuals were marked by a white peg. As the colonies developed and grew in size, there was a tendency for them to intermingle.i When intermingling occurred to such an extent that accurate counts could.not be made, the colonies were discarded. In the 1960 studies, the intermingling of colonies was prevented by destroying all un- marked colonies which were in close proximity to marked colonies. Hany'young colonies, derived from newly germina— ted statoblasts, were found closely associated or in direct apposition at the thme that study colonies were first chosen. After certain young colonies were randomly chosen for study, other young colonies and ungerminated statoblasts in the -166- Pumateilo. $9913 growth 3m Q L . esiqnated bx, Colored plastic ‘32:?” . v ,, ' .) .A ‘ 1e‘1'.\§ .‘ r ”I \ _‘- ’ v t 1' l,’.¢", J. "- -. ‘4: MA _-¢. -167- immediate vicinity were sacrificed. Later in the study, some colonies, which had been formerly'widely separated, grew so that they threatened to intermingle. In this case one (or more) of the colonies was destroyed. Sometimes the destroyed colony was an.unmarked colony and thus not impor- tant to the study3‘but at other times both approaching colonies were marked colonies. One of the colonies was then removed and the collection of growth data on this colony was discontinued. Colonies to he removed were scraped off the substrate with a blunt probe or a small pen knife. The sub- strate had to be scraped clean to assure that none of the mutilated colony remained, as the subsequent decomposition of dead polypides would tend to alter the environment of the closely associated colonies. Through vigilance, germinated statdblasts, newly settled larval colonies, or expanding older colonies could be observed and destroyed when necessary. This made it relatively easy to follow the progress of the marked study colonies. Random choice: The choice of study colonies was arbitrary. Most colonies were sufficiently separated, so that all of them could be marked for study; When germinating statoblasts were closely associated, a number of young colonies, as pre- viously described, had to be removed.‘ This process was essentially at random, as a choice was made quickly and with- out the aid of the 10x or 20X lenses. By using this method no preliminary appraisal could be made relative to the effi- cacy of the site or the robustness of newly germinated -168- polypides. After sacrificing certain of the closely asso- ciated small colonies, the hand lenses were used to ascer- tain whether the chosen polypides were actually alive. Polypides were recorded as living when the lophophore was evaginated. Checking colonigs: Not all stations were selected on the same date. However, numerous stationswere established in late April on both lakes. After a station was designated and a number of colonies and individual polypides had been marked for study, subsequent examinations of the colonies were made atregular intervals. This interval was generally seven days. The time required to check the numerous colonies on each lake varied from two hours to seven hours, depend- ing on the number of colonies under observation at a given time. Observations at the two lakes were made on different days of the week. Habitat observations and.temperature readings were made. each time that the colonies were checked. Other data were obtained less frequently. The observation of the individual colonies was a painstaking routine. Substrates were turned over so that the colonies could be examined. The substrate was submerged every two or three minutes, and on clear days it was generally kept Just beneath the water most of the time to reduce excessive exposure to the sun. The author has kept non-study colonies out of water in the shade for two or three hours without deleterious effects. After the substrate was turned upward, each colony was -169- observed and the individuals in each were counted. These counts were made with the aid of 10X, 15x, and 20x lenses. The number of polypides in colonies of each color series was obtained consecutively. The counting of polypides had to be accomplished carefully, even with magnifying lenses, as a determination of the presence of small new buds was some- times difficult. However, buds are usually turned slightly to one side or the other of the coenecial growth plane, thus making them easier to see. Counting errors were minimized by recounting the polypides in large colonies, sometimes four or five times. The counting of larger colonies was facilitated by the use of a miniature quadrat develoPed by the author (Fig. 56). A small square frame was constructed of quarter inch doweling. Fine drill holes were then made at one centimeter intervals along all four sides of this frame. The frame was strung like a tennis racket usinga fine, colorless.number two nylon leader. This miniature grid (foundrvaluable by the author for counting all sessile invertebrates, including Protozoa) is an adaptation of the field quadrat method of terrestrial ecology. By placing this grid over large celonies, the polypides‘withnn each of the squares could be counted and recorded, thereby assuring an accurate polypide number for each.colony, It was not necessary that each polypide be extended or even alive for purposes of studying colony growth. As long as the total number of polypides which had beenbudded by a particular colony could be determined growth data could be - 170- F'uj.56. Mivfiotture qfid dNidEci ln‘to one centume’w' squares ubed In Countmc} denSe Bryozoqn Co onies ~171- obtained. Often the colony was composed mostly of living polypides. In some cases, when polypides in the older inner region of the colony had died, the coenecium and its sepa- rate zooecia were still easily discernible. Thus accurate polypide counts could still be made. When disintegration had proceeded so that portions of the colony were lost and fragmentation was definitely in progress, it was necessary to record an .35. after the polypide number indicating an in- complete count. Such a colony was no longer of use for the growth study. When entire colonies were destroyed by pre- dators, the loss was recorded as gross mortality. It was necessary to verify that polypides being studied for longevity data were still alive. This was done, each time the lakes were visited, by either waiting for the poly- pides to evaginate or for the zooecial tips to move. Veri-. fication may~even be made on retracted polypides, because when alive the tentacular sheath appears as a sharp thin line suggestive of the bore of a fine pipette. The digestive tract is distinct in living polypides, while in those under- going decomposition, the digestive tract is globular, and the tentacular sheath is diffuse and.milkybwhite in appear- moo e RESULTS Growth Growth and mortality data are given in Appendix Tables 1 through 37. Each of the colonies is designated by a symbol, in most cases a letter or letters followed by'a number. The numbers of polypides in the colonies were recorded at regu- lar intervals. The data plotted on the growth graphs (Appens dix Fig. 1A,B - 28A,B) were obtained from robust and actively growing colonies. Budding was erratic or retarded in numerous colonies, as is evident in the Tables. The apathetic colonies were not representative of the growth potential for colonies of Plumatella repens and were therefore not graphed. Growth data were graphed to determine whether populations of.§. repens exhibit geometric increase. The data for more than 50 individual colonies, and SO multiple colonies were plotted. The multiple colony graphs were plotted from averages Obtained by totaling the number of polypides in several colonies. Only colonies chosen on the same date, at the same station, and with the same initial number of poly- pides were combined. The number of colonies included in such a composite population total was variable and is indicated on the graphs. The data for the colonial populations were first trans- ferred to graphs (Appendix Fig. 1A - 28A) on which the natural logarithm.of the number of polypides in a colony or colonies was plotted on the ordinate, and the number of days from zero time was plotted on the abscissa. A straight linewas then drawn along the linear course of the points, after making -172- -1‘73- certain that approximately equal numbers of them were present on either side of the line. Somewhat less weight was given to the first and last plotted points where they deviated from a line which was otherwise dictated by all the other points. Second graphs (Appendix Fig. 18 - 283) were then constructed to exhibit growth rate on an arithmetical scale. These graphs in general followed the equation: I hh;=rdo ert -where‘§g is the initial number of polypides in a colony or the mean number of polypides (in the case of multiple colony graphs) at the time that observations were begun, and 31* represents the population number at the end of‘t days. The base of Napierian logarithms is _e_, and 5 is the instantaneous growth rate. The value of g'is obtained as the slope of the straight line graph. . Finally, the doubling time (i.e., the time required for a colony to double its polypide number) was computed and is indicated at the bottom of Appendix Fig. 1A - 28A. This was computed by dividing the natural logarithm of two by'E, Doubling rates were computed for many colonies not included in the graphs and were consistent with.those given. Mortality Gross mortality is indicated in Appendix Tables 1 through 37 by an E. The letter 5 indicates that no trace of the . colony (or at least no more than a few sessoblasts or frag- ments of zooecia) remained on the date that the; was recorded. Other symbols are used to indicate that the colony was income -174- plete on that date. Colonies were often incomplete due to partial predation or to natural disintegration of portions of the colonies. When a number precedes the letter K, it indi- cates the number of polypides remaining in a colony which has been partially destroyed. In such cases either single polypides or larger parts of the colony, sometimes growing tips, were missing. This type of attrition appeared to be patternless snd.predation was assumed to be the main cause of colony incompleteness. In contrast, disintegration of a colony generally follows a pattern, taking place from the center of the colony outward. In this case, the isolated growing tips which remain, are the remnants of former large complete colonies. Therefore the term "tips" in the Tables implies that the older central portions of the colonies were essentially absent, as a result of natural disintegration. 33 and fig are desigxations applied to colonies which were "partly gone" or ”mostly gone", respectively}, Whether colonies so indicated were incomplete as a result of pre- dation, disintegration, or both.was not clear. The symbol‘g! stands for ”too mixed" and indicates that colony growth or the intertwining of zooecia was too complex to permit an accurate polypide count. This condition resulted when a single colony became too dense to count, or when two or more colonies had become entangled so that their respective polypides could no longer be reliably determined. The term TEE implies that the colony was too densely entangled to count and was also incomplete. -175- Gross mortality, or total colony predation, for several stations is plotted on the natural logarithm versus time graphs (Appendix Fig. 29 - 56). Longevity Appendix Tables 38 through 42 give the field data on longevity for 373 marked polypides. The letters in these Tables refer to the colors of the pegs which were used to mark the polypides. In cases where only one color symbol is given for the individuals marked at a station on a given date, all polypides were marked with pegs of the same color. It was not necessary to give symbols to each polypide in studying longevity, as only the total number of living poly» pides was recorded. In a few cases polypides were marked with two pegs. Appendix Fig. 37 is a survivorship curve, prepared from the collective survival data on 373 polypides. The natural logarithm of the number of individuals is plotted against time. The following is a summation (from which the survival curve was prepared) of longevity data obtained from colonies at both lakes during the years, 1959 and 1960. 232 or 62.2% of the 373 polypides survived 11+ days 176 or 47.2% of the 373 polypides survived 21+ days 78 or 20.0% of the 373 polypides survived 28+ days 57 or 15.3% of the 373 polypides survived 31. days 12 or, 3.2% of the 373 polypides survived 37+ days 3 or .B% of the 373 polypides survived 46 to 55 days GROWTH DISCUSSION More than 100 graphs were plotted from individual and multiple colony growth data, and in all but a few cases a geometric growth rate was indicated for Plumatella repens. The geometric growth pattern is illustrated particularly well by colonies at stations 3, 7, 8b, 15, and 14 on Burke lake and at stations 5, l2, and 16 on Wintergreen Lake. At these stations most of the colonies appeared in good physical condition, and they were showing positive increase. This only serves to support the premise thatIg. repens proliferates new polypides in a geometrio manner, as the most favorable sites demonstrate most perfectly this type of growth. The colonies at these sites generally revealed the lowest doub- ling time, an additional indication of favorable habitat. Graphs demonstrating geometric growth are seen in Appendix Fig. 1A through 15A for Burke Lake and Appendix Fig. 16A through 28A for Wintergreen lake. Graphs plotting the theo- retical increase in the number of polypides are shown in Fig. 1B through 158 for Burke Lake and 163 through 283 for Wintergreen Lake. The Observed mean number of polypides for a sequence of time intervals was compared with the number expected from the geometric growth law. The observed and expected numbers were generally in close agreement. Appendix Fig. 28 gives both values for one of the stations on Burke lake. The observed number of polypides departs appreciably from the predicted number only on.ths last number. This discrepancy -176- ~1774 at the end of the recorded growth period suggests either the approach of the asymptote stage of the logistic curve or a worsening of environmental conditions. Several other colonies reveal this decline in growth on the final polypide count, but numerous others do not show the same decline, as may be seen by an examination of the graphs. In some cases, the graphs plotted for large colonies of several hundred polypides failed to suggest a leveling off of the growth rate, while the graphs plotted for certain smaller colonies did show this. Polypide counts of colonies which do not show this leveling off were, perhaps of necessity, discontinued too early; in effect prior to the onset of growth limiting densitybdependent and densitybindependent factors. It is not reasonable to assume that all colonies would reveal a decrease in growth rates at the same time. This phenomenon might relate to the environmental resistance existing in the vicinity of each individual colony. It is prObable, that the full biotic potential of this species is not attained, and that the rate of growth is in time progressively curtailed by environmental factors. Stations 1, 2, 4, 6, 9, and 10 on Burke lake and station 13b on Wintergreen Lake show, in general, fewer colonies with high and steady growth rates than do other stations, and at stations 1, 9, 10, and 11 at Burke lake, many eclonies reveal a nearly complete cessation of growth. These poorly growing colonies were of course not graphed. Graphs showing some slight deviation from the geometric growth pattern,evident in -178- the other graphs, are Appendix Fig. 5A for Burke Lake and Appendix Fig. 23A and 26A for Wintergreen Lake. In Appendix Fig. 5A, 13A, and 25A, the points representing later polypide counts are above the line and earlier counts are below the line. The tendency is evident in a number of colonies. It is essentially associated with colonies which were Observed beginning with late April or early May germin- ations. The tendency, of course, suggests a slowly increasing growth rate, in effect a tendency toward a greater steepness tn the slope of the growth line. This tendency is rarely seen in colonies which were chosen in early June or during the summer months. An examination of the doubling rates (Appendix Fig. 1A through.2aA) supports the contention that growth.rates tend to increase during the spring. The doubling rates for colonies marked in late April and observed into early June generally vary between 4.0 and 7.4, meaning that these colonies could be expected to double in size each 4.0 to 7.4 days. The doubling rates for many active colonies marked in early June and observed into July ranged from 3.4 to 4.9. This difference in the rate of colony proliferation suggests that either nutritional, chemical, or physical conditions were more nearly optimum.around the first of June. All of these factors may contribute to an increase in the rate of colony growth. However, the fact that the colonies at the favorable sites, which are the sites under primary consider- ation, appeared well fed and healthy from the end of April -179- into June, suggests that there was no lack of food at these stations. koreover, the abundance of other sessile animals (e.g., protozoans, rotifers), insect larvae, and.snails sug- gests that the chemdcal conditions were not restricting the animal community. If physical factors are considered, temp perature appears to be the most important. Temperature remained above 20 degrees centigrade from the latter part of May into the summer in both lakes (Table 43).‘ The increase in growth rate appeared steady in many of the graphs drawn for spring colonies and the growth rate was steady for most colonies observed during the late spring and summer. The steadiness of the increase in growth rate argues against the sudden rise of a particularly suitable prey species, and suggests instead an environmental element which is steadily changing in the spring and attains an optimum.during the summer. Temperature is of course such a factor. A somewhat greater number of the more successful colonies from Wintergreen Lake had doubling rates of between 4.0 and 5.0 for the late April to June periods than did colonies from Burke Lake. In fact, colony'Yb4 at station 5, Wintergreen lake, chosen on April 29, 1960, had a doubling rate of 3.75. Perhaps the somewhat lower spring doubling rates evident for Wintergreen Lake colonies may be attributed to more favorable nutrition. Even though successfully proliferating Burke lake colonies appeared adequately fed, planktonic food may not have been quite as nutritious as the Wintergreen plankton. Interestingly enough, plankton samples taken from Wintergreen -180- Lake during the spring and summer of 1960 contained a greater abundance of organisms than did those from Burke Lake, meaning that a richer food source was available to the Winter- green Lake colonies. This suggestion is strengthened‘by the fact that there were fewer colonies in‘Wintergreen Lake with sharply decreased growth rates. A drop in lake temperatures during the first half of May could have been responsible for the decrease in growth noted for some spring colonies. In the fall, budding ceased when the temperature fell to 9 degrees centigrade (see station 8, Burke Lake, 1959). Colonies at this station appeared well fed, so the steadily decreasing temperature was assumed to be the major cause of growth depression. An examination of the growth Tables for the different stations at Wintergreen and BurkeLakes reveals a great deal of variability among colonies at different sites. Certain sites, as stations 1, 5, and 9 on Burke Lake reveal a general colony apathy. The colonies at these stations had little more than begun when growth was depressed. Few of the colonies attained a size greater than four or five individuals. Algae, sessile animals, snailafand insect larvae were scarce at these stations. In effect the microhabitat at these stations was more barren than that at other sites.' The digestive tracts of the animals at these sites were fraouently not filled with food or were not as dilated as were those of animals observed at sites where growth was continual and regular. The stomach contents of the poorly nourished animals -181- were observed to be more hyaline. In the better nourished animals, the color of the stomach contents were generally yellow, yellow-brown, or green, and the digestive tracts were expanded. An inadequate diet undoubtedly helped to depress growth at these sites. { A variation in food did not appear to be correlatednwith an increase or decrease in growth. However, variations of diet, regardless of an abundance of food, prObably do affect growth rates. This has already been suggested for spring colonies in Wintergreen Lake. Rogick (1945a) declares that green algae are unsuitable food and that colonies of‘§z§l_- ‘ggllg punctata fed on green algae degenerated early. Green algae did not appear to depress growth or promote early disintegration in Plumatella repens. Many rapidly growing .colonies were seen from time to time with their digestive tract largely filled with green algae. However certain green algae are possibly a less suitable food than others for Bryozoa. Rogick found also that when food was both "adequate and suitable", buds formed and evaginated at a rapid rate. A growth study involving a continual analysis of the flora and fauna of a microhabitat would be of interest in order to determine the importance of specific planktonic organisms on bryozoan growth rates. As might be expected, both density-dependent and density- independent factors appear important in these growth studies. In addition to the densitybindependent factor, temperature, such factors as nearness to the bottom or nearness to dense ~182- plant growths, were seen to be associated with increasingly rapid disintegration of colonies. As the water level in the Burke lake outlet became lower and colonies were only one to three inches above the bottom, colony disintegration was accelerated. The growth of newly germinated young colonies was depressed when these colonies were close to the bottom, or enclosed by heavy vegetation. When a substrate became marooned on the tops of heavy plant growth, notably 22553 sp. (e.g., Q, vulgaris) in Burke Lake, there was a decrease in the growth rate and disintegration of polypides. The under- side of the logs were closely pressed into the dense vegetation. In this situation, movement of water was prdbably impeded. Noxious metabolites from plants and animals, including the ectoproct colonies, may well have accumulated in the poorly circulating water of such a microhabitat and initiated the deterioration of the colonies. Brown (1933) suggests that close association between Bryozoa and 23355 may be unfavorable for the former, because Bryozoa had never been found growing on 99333. The author has found four genera associated with 9.9.93.2: but not often. The retarded growth which was apparent in colonies situ- ated near the organic lake bottom.may have been caused by products of decay, bacterial metabolites, lowered oxygen, or increased carbon dioxide; thus density-independent factors. The metabolites of the Bryozoa themselves and the unavaila- bility of sufficient suitable food (after the colonies reach a certain size) are possibly densitybdependent factors. Both -1es- types of factors doubtless work in conjunction to depress growth and accelerate.the deterioration of colonies. a cyclic fluctuation was noted for populations of'g. repens. Many spring colonies deteriorated by late in June, and in early July sessoblasts produced by some of them, germinated and produced new colonies. These summer colonies formed sessdblasts which in turn germinated (a third genera- tion) in later September or early October. However, the decline in temperature in October precluded further growth, and these colonies proliferated no more than three to twelve polypides. In November these small retarded colonies died. Marcus (1926) discusses a second generation of colonies in the summer, originating from statoblasts produced in the spring. Polypide evagination rates for'glglinella‘punctata as given by Rogick (1945s5Table II and III) may be compared with those for‘g. repens in the present study. Rogick's data indicate that second polypides evaginated 6 to 18 days after first polypides; third polypides, 8 to 18 days after first polypides; fourth polypides, 9 to 20 days after first poly- pides; fifth polypides, 10 to 21 days after first polypides: and.sixth polypides, 13 to 21 days after first polypides. Fourteen day averages of numbers of polypides were computed for combined colonies, each of which was begun.with one poly- pide, at Wintergreen Lake. These colonies were located at stations 5, 10, and 12. In colonies approximately 14 days old the polypide number varied generally between four and -184- eight. These figures are in no way sharply at variance with Rogick's data, which showed that for five different colonies, the sixth polypide was present between 13 and 21 days after the first polypide had evaginated. However, the data for 2, repens were obtained for spring colonies, thus the water temperature was prdbably colder than that in which laboratory» reared colonies of'H. punctata were kept. Her data suggest that the growth rate of very young‘g. punctata colonies was perhaps only somewhat below that of the most actively pro- liferating‘z. repens colonies. The time interval between the evaginations of successive polypides of Lophopodella carteri (Rogick, 1935b) is in the beginning somewhat longer than for either'g. repens or‘g. punctata. Rogick presents data largely for two colonies of‘g. carteri which indicate that second polypides evaginated 19, 21, 38, and 43 days after first polypides; third polypides, 8 and 3 days after second polypides; fourth polypides, 2 and 3 days after third polypides; fifth polypides, 4 and 4 days after fourth polyb pides: seventh polypides, 1 and 3 days after fifth polypides; twentybseventh polypides, 7 and 8 days after‘eighth polypides. One of these colonies budded its thirtybseventh polypide 68 days after germination,and the other budded its forty-fifth polypide 70 days after germination. The time which these colonies required to attain 37 and 45 polypides is considerably greater than for the more actively growing colonies of‘g. repens. More slowly growing colonies, such as R—2 and H-3 at station 4, Burke Lake, only required an estimated 40 to -185- 43 days from the germination of statoblasts to reach the 41 and 42 polypide stage respectively. Colonies at stations where growth was depressed, of course, increased more slowly than the‘L, carteri colonies. Rapidly growing colonies of .2. repens developed 150 to 200 and more polypides in 35 to 45 days. The proliferation of the first several polypides of a colony requires proportionately more time than the proliferation of later polypides in colonies of all three species being discussed.‘ Early budding was particularly delayed in'g. carteri. (However, some increase in the growth (rate was noted in the proliferation of later polypides. One ‘L. carteri colony tripled during a seven day period. Many ‘2. repens colonies tripled in size in a seven day period. Some colonies of P. repens increased by four, five, six, and even seven times their size in a seven day period. Rogick (1938) gives additional growth data forig. carteri colonies reared in the laboratory. Second polypides developed 4 to 20 days after germination of the first polypides. How- ever, her data indicate that it todk from 30 to over 40 days for colonies to triple (from 6 to 18 individuals), and the lowest doubling time for a single interval was seven days (single interval doubling times are only comparable to single interval times forrfi. repens,not to doubling rates). Rogickvs (19459 data indicate that the most successful colonies of ‘5. punctata doubled in a period of three or four days, once they had attained a size of six polypides. Three colonies tripled (6 to 18 polypides) in 4, 5, and 11 days. Comparable -186- increases may be found in the data on'g. repens. Rogick counted the total number of polypides in her colony R-4b until it had 45 individuals, after which she counted only evaginated polypides. If the growth of the R-4b colony of‘g. punctata is graphed up to the forty-fifth polypide stage, an essentially geometric growth is evident. Admittedly this only represents a single colony in a rela- tively early stage of development. However, as the most successful colony of those studied, its growth suggests that another species of Ectoprocta tends to grow in a geometric manner. Certain colonies 0f.Z- repens reveal startling increases during a single interval of time. AColonies R-3 and 1&4 at station 5 and colonies P-3 and P-4 at station 6 on Wintergreen Lake, 1960, serve to demonstrate this increase. Several other colonies were observed to double one week and triple or quadruple the next week. Some sharp variations could be caused by temporary changes in the immediate environment of a colony; however, the author suggests that these variations are attributable in part to the nature of the budding process. On the maternal cystid wall, three buds usually form;a main bud'ventral to the vestibular region, a duplicate bud which is developed from the ventral proximal surface of the main bud, and an adventitious bud located on the side of the main bud nearest the mother polypide wall. When the main bud grows out and away from the motherpolypide, the adventitious ebud above it become the main bud of the mother polypide. The -187- duplicate bud becomes the main bud of the original main bud which has grown away from the mother polypide. This process has been observed by the author and has been studied in detail by Brien (1936, 1953). Incipient buds may be seen forming with close microscopic examination. However, when a number of mother polypides have a series of buds about to evaginate polypides, these are not readily apparent under low power magnification nor can they be counted as mature individuals. If, hypothetically, a majority of individuals in a colony each had incipient buds which were nearly completely developed, but still non-evaginable, then a count of the colony at this particular time would be considerably lower than a count of the same colony, a matter of a few hours or a day later when a particularly large number of incipient buds had become evaginable polypides. If each polypide of such a colony then proliferated one or more subsequent animals in addition to the-nearly mature polypides which had not been counted the week before, then the second count, several days later, would be relatively greater than that recorded at the previous obser- vation period. This third Observation could reveal a proper- tionate decrease when comparedwith the sudden comparatively large increase of the second observation. Rogick's (1945a; Table III) illustrates how different the data would be if a' polypide count of colony R-4b had been taken early on the 20th day after statoblast germination. Polypides 32 through 45 all evaginated on the same day. An early count in this case would have disclosed as many as 14 fewer polypides than ~188- a later count the same day. The 14 polypides not included in the early count would then be compounded with any additional mature buds proliferated by the next observation period. If a majority of polypides, in addition, had proliferated new mature buds Just prior to the second observation, then this latter count, by virtue of timing and the recency of a large- scale proliferation of buds, might have revealed a relatively unusual rate of increase between these two observation periods. MORTALITY’DISCUSSION Gross mortality, indicated by an §,in the growth tables, is graphed for a.number of stations in Appendix Fig. 29 to 36. The data are provocative, because they show that entire substrates were completely denuded of Bryozoa in only a few days. Often the chitinous (Hyman, 1958) coenecia and even the sessoblasts were removed from the substrate. In the case of many of the marked colonies only the colored pegs remained to mark the site of the expunged colonies. Stations 5, 6, 6b, and 9 (Appendix Fig. 29, 30, 31) at Wintergreen Lake and, stations 2 and 5 (Appendix Fig. 32, 33, and 36) at Burke Lake demonstrate especially well the sudden annihilation of Bryozoa from a substrate. These data suggest that the Ectoprocta may play a reasonably important role as a prey species. Mar- cus (1925, 1926) states that tendipedids are noteworthy predators of Bryozoa. The author has not observed excessive predation by these animals, but has observed it by Trichoptera. Such large scale predation suggests the possible survival value of the thousands of statoblasts produced by the poly- pides of Elumatella repens (often 15 to 20 per polypide) on a single substrate. Sometimes one portion of a substrate was attacked by predators and later another portion was attacked. At station 9 on Wintergreen Lake,'colonies G—l through G-6 were missing on may 13, and most of the remaining colonies were gone on June 7. The second wave of destruction included a number of large colonies. This does not_indicate incidental predationcn- -189- -190- predation on an occasional polypide, but rather a methodical and total obliteration of all polypides. This destruction of colonies, on one area of the substrate at a time, is also evident at stations 2 and 9 on Burke’Lake. From these obser- vations, it appears that predators may sometimes concentrate on just one portion of a substrate. Increased numbers of snails and insect larvae, particularly Trichoptera, have been noted on substrates, concurrent with heavy attrition of bryozoan colonies. These same predators have been observed attacking and devouring polypides in the laboratory. Possibly the periodic devastation of bryozoan populations was associ- ated with a peak in the population of certain predators. Further examination of the data reveals that certain sub- strates are singularly free of gross predation (e.g., stations 6, 7, 8b, 13, and 14 on Burke lake; Appendix Fig. 32,343,36). Substrates which were largely free of heavy and sudden pre- dation, were those substrates which were net closely appressed or surrounded by dense mats of vegetation or by other sub- strates. They were in most cases fixed in open water, (or in areas of moderate plant growths) in the slowly flowing current of the outlet, or they were fixed outside the perimeter of the dense shore line vegetation. These substrates were often held in place by a thin projecting tree root or by'a stick across the outlet. Those substrates partially resting on the bottom, surrounded by dense vegetation, or closely appressed .on both sides by other substrates were naturally more acces- sible to crawling predators, which were often found heavily -191- concentrated in the vegetation. Thus where the substrate was not easily accessible to crawling predators, or where the substrate could not readily be used as a bridge to other substrates, predation.was reduced. The question of whether site of chance played the primary role in determining which colonies survived predation merits attention. If there was a sharp decrease in the number of- colonies on a substrate, followed by a leveling off in the predation, it might be concluded that either the colonies had the most satisfactory sites, or the number of predators had decreased. When predation is high, then the suitability of a site is tested. At many of the sites, the substrate was a flat plank. There were some substrates, however, with splits or checks in the wood, or with rough.bark, which by the nature of their irregular contours offered some colony site variation. Colonies G-l, C-2, and G-3 at station_3 on Burke Lake, were located on the roughened end of’a plank and retained their colony hntegrity longer than any on this plank. Probably it was the special location of the colony, being on the end farthest away from contact with adjacent substrates, which accounts for these colonies being spared. The chances of predators proceeding to the free end were less than for other locations on the substrate. Station 12 on.Wintergreen Lake was a roughpbark log. Large colonies had developed on this substrate, but within approximately two weeks, there was no trace of a polypide on the five foot log. Colony R-l, composed of more than 1200 polypides, had been completely -192- obliterated in approximately 10 days. Only one or two of numerous sessoblasts were still found cemented to the substrate. There were colonies on certain substrates, which had grown down into very thin checks in the wood. On several occasions these deeply entrenched colonies were the only ones left on a substrate. These colonies were not marked, because of the impossibility of making careful observations on polypides. Their survival was probably attributable to a favorable site. Large predators, such as most Trichoptera lArvae, snails, and fish, could not reach them. These colonies were still acces- sible to many tendipedids. The graph for Wintergreen lake, station 8 (Appendix Fig. 29), shows a gradual attrition of colonies. Other substrates with a similarly uniform.surface demonstrate a relatively constant attrition. These substrates were probably subject to the continual movement of a limited number of predators across their surfaces. There is nothing to indicate that certain sites were more suitable at these stations. In time most of the colonies were removed or partly removed which suggests that chance is the primary factor operating in the sequential attrition of these colonies. As indicated earlier, the location of a substrate with reference to its closeness to vegetation and other substrates is correlated with a high attrition. Chance plays, perhaps, 'the major role in determining which colonies on a substrate are ravaged. However, the physical restrictiveness of a site J may preclude decimation by certain predators. LONGEVITY’DISCUSSION The longevity data reveal that Plumatella repens polypides survive between 4 and 53 days. Neither the time that each of the polypides had existed prior to being marked, nor the time they survived beyond the last observation is known. There- fore, longevity data represent minimal time, and an unknown plus value may be assigned to each longevity record. This plus value may conceivably vary from a few hours to a few days. Longevity data were obtained from polypides in colonies which appeared to be healthy. Station 1 at Burke Lake was an exception. None of the polypides studied at this station lived longer than 19 days. ~The survivorship curve (Appendix Fig. 37), based on 373 polypides, indicates an appreciable polypide death rate between 21 days and 36 days. The_maximum longevity was 53 days, recorded for one polypide from station 4 and one from station 5 on Burke Lake in 1959. Two polypides survived for 44 days, and still others, for more than 35 days. Hyatt (1868) states that Bryozoa with stiff ectocysts, such as Plumatella and Fredericella live longer than Bryozoa with gelatinous ectocysts, such as Cristatella, Lophopus, and Pectinatellg. However, he offers no concrete data. marcus (1925) estimated that few bryozoan polypides live longer than six weeks. Brooks (1929) declared that polypides of Pectinatella magnifies remained alive for six weeks in the laboratory, and Rogick (1938) reports that ancestrulae (first polypides) of Lophopodella carteri live from 6 to 47 -193- -l94- days and subsequent individuals for a shorter time. Narcus (1941) estimated that polypides of Stolella evelinae live for 3 to 4 weeks. The data given by Regiok (1945» for ‘Hyalinellg punctata indicate that the longest lived indi- viduals die sometime between 3 and 4 weeks. The longevity data for Plumatella repens overlap, in rango,the data given for other species. Rogick (19456) indicates that ancestrulae of _H. punctata were generally the first to degenerate, the process taking (place between 3 and.21 days after statoblast germination. This is a considerably shorter life span than the 47 day maximum longevity that she recorded forlg. carteri. Four ancestrulae of'g. repens lived from 29 to 32 days: two B polypides from station 4, Burke Lake, 1960, survived until may 29; one P polypide survived to the same date at station 10, Burke Lake, 1960- The ancestrula of colony R-l at station 12, Wintergreen Lake, lived 29 days and possibly 11 days longer. The density of the colony at the time of the June 7 observation, made it difficult to determine which of two polypides, one alive and onedead, was the ancestrula. Rogick found that some colonies of‘g. punctata had 17 indi- viduals before the ancestrula began to degenerate. In colony R-l above, of.§. repens, the colony was composed of 76 polypides when the ancestrula was definitely still present. The polypide longevity data for.§. repens appear to agree more closely with those for Lophopodella carteri, than 4.95- with those for‘gyalinella punctata. However, comparisons nust remain somewhat tentative, in that the Plumatella repgns data were collected in the field, while the data for the other species were obtained in the laboratory. 1. 3. 4. 5. 6. 7. SDMMAHY’ The growth data suggest that the increase in the number of polypides in colonies of Plumatella repens tends to be geometric. This tendency is most clearly revealed by colonies growing under favorable conditions. Robust colonies at the more favorable sites doubled in size each 3.4 to 7.4 days. The summer doubling time was 3.4 to 4.9 days, and the spring doubling time was 4.0 to 7.4 days. Growth.was often erratic. many colonies, duringia single seven day interval, failed to double, while others increased four, five, six, and even seven times in size during a single seven day period. Some colonies attained a size of approximately 40 polyb pides in a 40 to 45 day period, others proliferated as many as 200 or more polypides at the end of a 40 day period. The growth rate was affected by temperature, extreme nearness to dense plant growths (e.g.,‘ggg£3) or to the marl-organic lake bottom, and by insufficient food. Growth.was completely depressed.at some stations, with colonies rarely surpassing four to six polypides. Predation on Plumatella repens colonies was very high at a number of stations. Colonies of several hundred polypides were sometimes destroyed between two obser- vation periods. Occasionally an entire substrate was denuded of colonies. -196- 8. 9. 10. 11. 12. 15. ~19?- (Colonies located largely free of dense vegetation and not too close to the lake bottom were believed the most suc- cessful, because they were less accessible to crawling predators and deleterious chemical effects. Colonies located in small checks in the surface of a substrate were seldom victims of predation. The physical limitations of such sites protected the colonies from predation by fish, snails, and most Trichoptera. Colony attrition was steady and gradual at many stations suggesting that chance, rather than site, was of most importance at these sites. (Longevity data for 373 polypides were obtained. Pluma- £23.19. repens polypides lived from 4 to 53 days. The polypide death rate appeared to be highest between 21 and 36 days after statoblast germination. Few polypides lived longer than six weeks. Eighty per a cent of them died within 28 days, and only 12 of the 373 polypides studied lived longer than 37 days. APPENDIX - 198- Fig. 1A. Relation of natural logarithm of the number of polypides in colonies with time ', for 24 colonies each begun'with one ' ' polypide. chosen at Burke Lake, Clinton County, station 3, April 27, 1960. b5»- b0 -— // $5.- 7_ 5.0 L— /’ 5 3 4.5L / 4.0 "- $ r— , ‘9 '31 35 / .— ' F a (4— /'s s o 30'- f/ y i /' 21’ g 205}— ‘4. c i If d— ! I o 1.0)- /.’ C 3 / “' ? . / i5 :— / l \‘o L f 5 r— -’ / / 1 1 ,L L J 1 ,,-1.__..ll__ J I _ o [0 2.0 50 '10 50 Deb‘s Doubhnq ra’te. 5. 3 8 To+al Popu‘O'hon ‘150L 900 r- PiSe In ~199- Theoretical increase in the total number of polypides for 24 colonies. begun with one polypide each, chosen at Burke Labs, Clinton County. station 3. April 27. 1960. ‘ . ‘ -200- Fig. 2A. Relation of the natural logarithm of the number of polypides T 5.5 6.0 n- 9 ‘1‘ 3.0L. bl m I \n of. number of pokfifides m Color“! '9 m 0 m I ”"T‘" q I LOL— in colonies with tin. for colonies G-l, G-2,'and G-3, each begun with one polypide, chesen at Burke Lake. Clinton County. station 3, April 27. 1960. DOuanc‘ rode. 5. 3 _7) To+ol popuj aTu'on Iooov -201- €150 - Fig. 23. Theoretical increase in the total number of poly- pides for colonies Col, 9-2. 6-3, begun with one Cloo *- polypide each. chosen at Burke Lake, Clinton County. station 3, April 27. 1960. _. E‘r‘d‘vdl‘k'tl mbe 850 Txme. c‘ua ‘Ogumeg‘e‘r§ Pojpm‘e. Haugo‘fifgggu Y T: L) \. b8 1 -OO 800w- : H 4.18 14.00 ‘Ta \8’ i058 \3-00 75°F T: 15 2.5. 79 23.33 T: '51 n+0? AS'. 55 =39 \59.|7 l83.53 700)- T. ob 3615.50 400.00 . 11:53 481.5% 800.00 I tso .. I I i boa ’- 5503-— 500.“ .\ L1‘50"- t—loo; o 35.;— 300'- 156;- ) /' looj- ‘ h f 9 \So"' . t loo r— ./ 50 L- / i- ov-WT‘ff".—’|/L 1 mi... ”0.1, -..- -.i____...._L_._..-._.-L. O |O lo 50 '40 so -202- Fig. 3A. Relation of the natural logarithm of the number of polypides in colonies with tire, for 11 colonies, begun with two individuals each. chosen at Burke lake, Clinton County. station 6, April 27. 1960. 5.0-— 45¢- ? / 3 H-o- / a / g 3.5- ,/ . I / 3 'l x/ ’3 3.0}- ,// o— i ,/ 2' g " o g ,/ 0" 1.53" . cr- i / 0 s ‘ :3 1.0?- //.u/ L— I. C L5 . ‘6‘ _S l-oL- .14! . S *" i L \ _WL--.“ . ' I l l 0 )0 7.0 30 ‘40 Does Dmbl'unc} r Q'Te, 7. Li Toiol Popukx‘hbn -203- Fig. 33. Theoretical increase in the total number of polypides for 11 colonies, begun with two individuals each, chosen at 83" Burke Lake, Clinton County. station 6, April 27, 1960. -204- Fig. 4A. Relation of the natural logarithm of the number of polypides in colonies with time, for'colony G-z, begun with one'poly- pide, chosen at Burke lake, Clinton County, station 7, Jam 12. 1960e (0.5 )— bo +- / / r c 50b 1/ .9 ,--’ 8 £ /. C 45" _. / r: : - 1 4 0'— / 7" / 75 3 51- /' I» ; ,/ (+— g- / O ) r’ 5 50k / ’2 i .ll/ 3 1.55 {ttl/ § , j/ q“ : I O 1.0.)- / C u I _ L/ ‘6 , y I to?— .5‘ S L \ i L l i 4 J 1 O ' Does DOub‘;nC‘ reds 4.7.5. -205- Fig. 4B. Theoretical increase in the total number of polypides for colony o-z. begun with one polypide, chosen at Burke Lake, Clinton County, station 1, June 12. 1960. Izwr- o HOG“- I000!- Ciao- 700' (poo _- To+o| Populoiion 400 P 300 i-- 200 )- \00 r- / ’1‘. 6‘. In of number a? Polsioficies. in colonxl -206- Relation of the natural logarithm of the number or polypides in colonies with tine. for eight colonies. etch begun’with two individusls. chosen st Burke Lube Clinton County, station 7 , April 27. 1960. . 4.0- /// 3.5% / /"I 3.0- l/. ‘ / / I I I I l 2.0 50 go 3:115 7.37 Doubhnci ml’e -207- Fig. 63. fheoretiecl increase in the total number of polypides for eight colonies esoh begun with two individuels, chosen at Burke Luke. Clinton County. stntion 7, April 27. 1960. 50" r. 40}- ° L. c 3"” .9 _p .9 _. 3 D— Q C 4' 7.0}— E ,9 n. \o— /. \n of number of ?o\\'?&c\es in Coioru' -208- 315. 6A. Dalstion of the natural loserithn of the umber of polypides in colonies 'vith tine. for colony B-l begun iith three individuals. chosen st Burke Inks, Clinton County, station 1, June 12, 1960e 65- ° be +— ~+sp 4.0 h- as- / / zsw- /// 1.0.. /' L5!- 0 LO" .5 P 1 i L L -.__...L-.-.....-.-.L J _4 _I 0 \o 10 3o ‘40 Dax‘S Doubhnfi (0+9. 3.8b ‘To'i'ai Popui 01’; on -209- Fig. 63. Theoretical inoreue in the total number of polypides for colony B-l begun with three individuals, 'chosen at Burke Lake. Clinton County, station 7. June 12. 1960 Howr- ' 1500b Hoar- i300 #- noo- HOO- IOOO" CPoo- 7007“ 6003-- 500}- L400 F— 300 >- \oo '- - / -2 1.0- [15, u, Relation of the natural logarithm of the number or polypides in colony with time, for colony I—l begun with one'indisidual. chosen at Burke Lake. Clinton County. station 7, June 12. 1960. 6.0? . 5.5- r "6 o c 45r- ‘3 a5 4.0,... I '5. 2‘ 3. 3.5r- / I ‘6' / lg 30}- / s . /' g 1.5L- ,O/ / ‘3” 2 / 5 or / 1 L L- L_ .1, mm.,}, l 0 ‘0 7.0 30 :Doxis .Doubfinc‘ ral’c 3. 8 5 To+o‘ Popu‘Q‘Hon -211- Fig. 73. Theoretical increase in the total number or polypides for colony I-l begun with one individual, chosen at Burke Lake. Clinton County, station 7. June 12. 1960. 55.0”“ e Soc?- I400 "T 350 *’ Boo _- 250- 200 "' \So- Fig. 8;. Relation of the natural logarithm of the number of polypides ’ in colony with time. 't‘or colony P-l begun‘with one indiridual. chosen at Burke lake. Clinton County. station 81:. Hay 8, 1960. .515 -.* 5.0? l‘ C o - ’ lb 5 o A i U ! c a - ’ 4.0 -— n f U a ’0 i .a_ 30$“. 3’ . x’ 0 ? /. or . / ‘*- 3.0?— l// 0 S ’/ z i ’g 1.5;" / 5 z . C 7“ O i- e Kr- ! 1 o s x 5 '/ E l 51— [/1 l o L— / ./. /, 05"- .1, ,/ x L fiL L_ 0 )0 2.0 DQ‘S DouquIINq Ydle. Li 5 q -213- Pig. OB. necrotical increase in the total nunber of polypides tor colony P-l begun with one individual. chosen at Burke labs. Clinton County, station 8b. lay 8. 1960. 250? P . 'LooF \50?‘ C o L.- *3 3 a. 3, \00 ~— :3 0 L I'" e 50»- T‘ /e . M'/ I; J 1 1 I \ 0 no no 30 Ho -214- ’1Se “e Rolation of the natural lOgarithn of the number of paly'pidec in colonies with tins. for {its colonies each begun with three individuals. chosen at Burke Lab. Clinton County. Itation 7, Jun 12' 1960c '7.o - Io-SI" b.0r- 0 5.5L- / Z‘ / ' —9 / o 5'°I’ _ o g / c l ./ “ 4.5!— d) 4): . , 'a— LLOI— // .2- I , O ' // q.— o /' 3 3.0L ,0 E 5 C 25*- q... ° 1 _E ZOOI- LSI‘. I-OII- .5» 1 I _.-_I_ I I I L I 0’ Io 2.0 50 40 DoubIInci m‘Ie 4.30 'To+n\‘poPuIakIOV\ ’1‘e 930 850 - 750r VooL b50~ boo- 550!- 500~ I-ISO~- I50“- I00 "‘ 50L- -215- Theoretical increase in the total number of polypides for five colonies each begun with three individuals. chosen at Burke hke. Clinton County‘ station 1. June 12. 1960. In Of number of POI‘f‘IC‘QS in CoIonY -216- P15. 10;. Relation of the natural logarithn of the nunhsr of polypides" in colonies with tins. for colony Y-l begun with'one individual. chosen at Burke Lake. Clinton County. station 14. April 21. 1960. 5.5 —- / 570- // ,v‘// 4.5?- ’/ 4.0 I- ff .O/. 3.5? ,3" 5.0r ‘ 15 - fl" . 2.0 - fl / .‘/ 3 L54— ’,-/ / Lor- . S‘I— // l 1 L L l J L L l I o \o 20 30 ‘I0 50 130.15 Deublmfi roie. 5. I7 _To‘IaI Pop ul :1ro n Fig. 450 400 -217- 10!. Theoretical increase in the total number of station 14. April 27. 1960. l-”.r-.- 200 I50 I00 SO I'"' I polypides for colony T-l begun with one indie I- widual, chosen at Burke Lake; Clinton County, I In of numbers of PI‘IPI‘Ies in CoIoan Fig. lue (0.5... 515» 15»— 1.0L. -218- Relation of the natural logarithm of the nusber of polypides in colonies with tins, tor ll colonies begun with one indi- vidual each. chosen at Burke Lab, Clinton County. station 14, ipril 27, 1980. I i I J ___._L _1 '° 2° 3° LID 50 “Day‘s v0ubIIhq TO‘I'e, l"I.85 IO‘I’aI PopuI o‘I’Ion _— -219- Fig. 113. Theoretical increase in the total number of polypides for ll colonies, each begun with one'indiwidual. chosen at Burke Lake. Clinton County. station 14. April 27, 19,60. Boo F 750 r' 700 r- bso +- boo L- 550L- 500 ,— 400? 350.— 150 '- IOO "' \S'O r— \00'- . - «~220- Pig. 121. Relation of the natural logarithm of the number of polypides in colonies with tins. for colony Y—‘I, begun with'one indi- vidual. chosen at Burke Labs, station 3. April 21. 1960 “t5" 2.. 0 4.0” '5 (J .S 3.51- \n «‘3 ,7.‘ Oh 2.5:— 0 I 5 L ’0 2.0I , // E ; / :5 I / C \.5’ .h V / o I ’C— Ivor II/ I ’/ I '/ -5I“ / I _ u 4 1 L l r I o lo 2.0 30 Denis DoubImc‘ role I‘I-IOZ -221- Fig. 123. Theoretical increase in the total nuaber of polypides for colony T-‘I. begun with one individual. chosen at Burke Labs. Clinton County. station 3. April 27. 1960. 150 I- I" . C .9 4— >— 3 I00 3 o. g_ r- ‘3 ‘5‘ 50 L- I“ /. O / him—“’1’ 1 4 I 1 1 l o no 20 30 ‘IO Pisa 13L. ~222- Relation of the natural l‘egaritha of the number of pOlypides with time. for colony B-t‘. begun with'one individual. chosen at Burks inks. station 4. April 27. 1960. usr r C '33 ' ““°‘ ; .9 5.5"— W . 3g . a. 5.0I— / . 42‘ . /. 0' I —+— ,— 0 1.5 ‘v 3 ,, 2.0L E O 3 5 ‘5‘ “SI- 5 0 /1I 05 "/ 1 l I l L I I A 0 IO 10 30 “IO DeubII mi val e b- 05 Total ”popular? I on ~223- Pig. 133. Theoretical increase in'the total number of polypides for colon B-d.‘ begun with one individual. chosen at Burke Lake. Clinton County. station 4. April 27. 1960. I00 L So *‘ I, /‘ / o Is +~—-——-—r.—-'j/. 1 _J 1 J 1 I0 10 30 t—Io In of number Of pokflmdes in CoIoncl -224- Fig. 14A. Relation of the mtural logarithm of the number of polypides in colonies with time. for'colony' Tbegun with two individuals. chosen at Burke lake. Clinton County. station 4. June 20. 1959 (aoa 5.5.. 2.0r‘ I5— L07 L L L I I 0 IO 20 8%— '40 Dan’s DoubIlnc‘ voile. 4.42 -225- Fig. 148. Theoretical increase in the total number of polypides for colony I begun with two individuals. chosen at Burke Lab. station 4. June 20. 1959 Boar I— 0 25'0" r‘ 200* +— C .9 ‘H d I50:- ‘3 ! a. o 0.- ~— 3 o _. r’ \00 50-- 0 e/ / I L I l 1 L -226- Fig. 15A- Relation of the mtural legarithm of the number of polypides in colonies with time for three colonies. each begun with a two individuals. chosen at Rurb Lake. station 4. lay 17,.1959. 5.5- 50+- 4.5+— 4.0}- 35' T \ 2.5 - ’ 2.0- ,/ In of number 0f POI‘IPICICS in OoIonY (N O I \: Dcu'S DeubIInq ml 6, LI. 50 -22'7- Fig. 163. Theoretical increase in the total number of polypides for three colonies. each begun with two individuals. chosen at Burke Lake. Clinton County, station 4. May 17. 1969 250 P 200 ISO” 100 r- " / O ‘ a lo _ 20 50 -228- Fig. 16A. Relation of the lateral logarithm of the number of polypides ‘ colonies with time "for colony I-S, bégun'with two individuals. chosen at Nintergreen Lake. Kalamasoo County, station 5. April 29. 1960. 4.0 - r C _9 8 3.5?- E ‘ ‘3 3e— —e . '8. I 7. Q.- I 2“- ° 2.0L- 3. cu ,o E I‘5 '- / 3 r c / ‘3" nor / c / .5I— 1 L l 1 1 I 0 IO 20 30 Douinnc‘ role. 5.2.4 -229- Fig. 183. Theoretical increase in the total nusbe'r'of polypides for - colony l-3. begun with two individuals. 'dmoscn at'Winter- green lakc. Ialamasoo County. station 5. April 29. 1960. Zoo- 1— ISO - C. I- .9 _P ,9 I00 .. 3 a. O s D- +- ’3 .18 o [- 50 F‘ O I— / fg/r’.’7/ 1 L L 1 o lo 2.0 30 -250- Fig. 11A. Relation of the mtural logarithn of the tutor or polypides in colonies with time. for 10' colonies'each begun with one individml. chosen at Iintergreen lake. Kalamasoo County. 5.5- 4.9- 5.5— / 3.0L / In of number 0f poIIpides 'm CoIoml 2e5- 2.0I— IeSI'" . LO '- 05 "" L l L l I L l J 0 IO 20 3O LIO Dan's Ecuinnc‘ role I4.06 -231- Fig. 17!. Theoretical increase in the total number ot'polypides for 10' colonies. each begun with one individual. chosen at lintergreen lake, Kalamsoo County. station 6. lay 6. 1960. N O __0 ' " "T"""‘1 ‘ ‘ I «7. o 8" “fold POPLL‘CItiOh I..',_..-.._T--.-_-_ ‘ -232- Relation of fine natural logarithm of'the number of polypides piSe 1“. in colonies with time for colon; G-“I. begunwith'onc ’indi- vidual. chosen at Wintergreen Lake. Ialasnsoo County. station 9. April 29. 1960. 4.5— ? +0“ 0 ‘3 y g 351. a") a—‘Cj 3.0;7' / .2”— I / 3. 2 s— , 3 I / g 1.07‘ y/ E : / 3 / C ‘esr / Lk—~ O E 20 30 D (“I s DoubIInc‘ role LLBI -233— Fig. 18!. Theoretical increase in the total number of polypides for colony 6-7. begun'with'one individual. chosen at Wintergreen lake. Kalamsoc County. station 9. April 29. 1960. LIo 3OI- “II-0+0! POPu'GfIOOn 10*" \oI— ~234- Pig. 19A. Relation of the natural logarithm of'the number of polypides cc. qI- 5.5-- 52w- )~. E ‘° 45 8 ‘ r .S In 4.0L- “ I .‘9 I Q. , r 0 C1. K.._ O L CI ,0 E 3 C 3‘ _C in colonies with time for colony Gel. begun'with one indi- vidual. chosen at Wintergreen Lake. Kalanasoc County. station 8. April 29. 1960. I . J I I L A 20 30 t-Io Daxls Douinnfi rate— 4.30 TotQI POP”, I 0110” -235- Fig. 19!. Theoretical increase in the total number of polypides for 500 L¥30 LJCMD 300 31157<: \:sr<3 \¢:><:> colony C—l. begnnnwith'one individual. chosen at”lintergreen Lake. Ialamasoo County. station 8. April 29. 1960. 0 I0 20 50 Ho Mg. 201. I 0 number 0 - n f I fon‘FICItS I“ QOIQn Relation of the natural logarithm of the number of polypides in colonies with time. for five colonies. each begun with two individuals. chosen at Hinton-green Lake. Kalansoo County. station 11. April 29. 1960. DCL\I S DOubIn'mi role. LI.CII -237- Fig. 203. Theoretical increase'in the total number‘of polypides for five colonies. each begun with'two'individuals. chosen at ' Wintergreen Labs. Kalamsoo County, station 11. April 29. 1960. 10- - 50:- 3 LIO- ‘T’o‘I’Q I pop“ ”the“ 20*” 10'— -238- Fig. 21A. Relation of the natural logarithm of the number or polypides in colonies with time Tor'sii colonies. each begun with'one individual. chosen at Wintergreen Lake, Kalasmsco County. station 12. April 29. 1960. 7:0" e.o- ./ 5.5 I \e 9.5 I. L10 I- /, 3.5I‘ / 2.5 - / In °I number oi M1963 'm Q°I°NI \ 2.0 More / 05"— Dues Douinnfi mic— LIbCI To'tCII PopuIcTIon “IOO' BooI- 150,. 700- 65d- (000*- 500L— 450 r. 490- 250 - zoo - \5’0 - '00?— 50*- 0? -239- Fig. 213. Theoretical increase in the tetal'number' of polypides tor'siz': colonies. each begun with'one individual. chosen at Wintergreen lute. Kalanm'soo County. station 12. April 29. 1960. -240- Fig. 22A. Relation of the natural logarithm of the number of polypides in colonies with time. for colony T—l. begun with one indi- vidual. chosen at Wintergreen lake. Kalamasoo County. station 12. April 29. 1960. 7.0 —- (9-5 " ° 6.0 I— 55 I- ‘ / /. Z” / 3 5.0 *- O o ,1 .2 us.- n . 0 I f? 4.0 - ‘ 0' x. 7. , 8' 3.5 I" , / / ‘4'" . ‘ O I; g; 3.0 - / s c 2.5 I- x” 9-4- ,"f O I C 1.0 I- 1‘" —— ‘/// ‘05 " // / / / |.o I- .5' I- I _L Iv L I I I I I I 0 I0 10 30 LIo 5'0 Dan’s Douinm‘ role, - 4, I01 To’mI popuhfion I000 r- -241- Q50- Pig. zznd'hcoretical increase in the total number of polxpides tor colony P-l. begun with "one 400- individual. chose'n'at 'lintcrg'rcen lake; Kalahsoo County. station 12. April 29, 1960. 850 r 750T- 700L- 650-- 500-- 200 L— ISoI. IOO .— \n of number of Pok‘nkdes in Co‘onxi ~242- Pig. 2“. Relation of the natural logarith’n of the master of polypides in colonics'with tine. for colon; R'. begun with two indi- viduals. choeen at'lintergrecn Lake, Kalamsoo County, station 11. April 29, 1960. 3.5- / 2 o —- / LS'L- . 1.0 r— o .5" 1‘ x t I J I 0 IO 10 30 Daxls Doubimq rate- b.8q To‘tcd PopuIat ; on -243- Fig. 233. theoretical increase in the total nfinber‘of polypides'f‘or colony, R, begun with one individual. chosen at Iintergreen Lake. Kalansoo County. station 11,. Lpril 29. 1960. L40r- 30- 20- 0 lo 20 30 \n of number of Pok’PQdes in Odor»! ~244- Pig. 2“. Relation of the natural logarithn of the number of polypides 4.5+ LO-' L5r- in colonies with tile. for colon! 1+8. begun with one indi- vidual. chosenoat linurgreen Lalo. Kalamsoo County. station 6. April 29. 1960. L, I I I I I ID lo 30 Daxls Doublinc' rule. “LC! 5 -245- Fig. 20. Theoretical increase in the total number or polxpides for colony Y—R. begun with one individual. ohoeen at hinter- green Lake, Kalanasoo County. station 5, April 29. 1980. 50}- ' To+o| PoPulcd'I on I \O‘" ~246- Fig. 25A. Relation of the natural logarithm of the number of polypides in colonies with time. for colony, P-S, begun with one indi- vidual. chosen at Wintergreen Lake, Kalamazoo County. Station 6. April 29' 19600 , / I I I I 4 I I- J O I o 2 9 50 Deni S Doubimfl rate — 4. 85 ~247- Fig. :58. Theoretical increase in the total number of polypides for colony P-S. begin with'one individual, chosen at tintergreen lake. Kalansoo Comm station 6. April 29, 1960. be” I 50 I- J‘. O T TotoJ POPuI afion‘ ‘8' T 20" IO"- Pig. 2“. 35r- Relation of the natural logarithm of the nudaer of polypides in colony with time, for colony r-z. begun with one indi- vidual. chosen at Iintergreen lake. Kalanasoo County. station 6. April 29. 1960. 7— 0 g , .2 8 3.0» .S 3 I... _‘U 1.5“ 5.. 3" 8' 200— . (J— 0 L “SL— o O .0 S 00" C l q.- 0 e _g .5I— I I I I I J 0 lo 20 30 DQxiS DoublInCI rate - b- 52 Fig. 263. theoretical increase in the total number of polypides for colony 9-2. begun with one imividul. chosen at Wintergreen Lake, Xalansoo county. station 6. April 29. 1960. - 10 I" e C .. .2 *3 7 ‘0 L’ e a. o A. / 4E e / i' /3 I I I I I 0 IO 20 30 4219- Fig. an. Relation of'the natural logarithn of the nutter of'polypides in colonies with tin. for seven. colonies each begun with one individual. chosen 'at'Wintergreen Lake, Kalanmsoc County, station 9. April 29. 1960. m co\on1 In 0f number of. poNPIdes Douanc‘ rale— 4.52. -250. Fig. 273. theoretical increase in the total nunber of polypides for sewen oolonies each begpn with ono'individual; chosen.at lintergreen Lake. Kalansoo County, station 9, April 29,- 1980. 255“ 200L r. 5 LP I50 L‘ .9 a I. « o D— "5 I00 I— .4..- o h" I r— 50 +- ' L ’///// e "/ we/ I I l I I _L 0 I0 20 3o lI0 \n of number of PWPQAes In CO\OH\I -251- Fig.3“. Relation of the natural logarithm of the number of polypides (0.0 53 5.0 I45 3.5 3.0 in colonies with tine. to:- col ' . G-Z ‘ ' vidual. chosen at Wintergreen fi‘ dm'é? one indi- etetion 3._April 29. 1960. at]. Dan’s Doubhnq raie- 5.10 -252- Zo&~ I‘IS'—- ' I50~ ’ I151— IOO I— To‘IoI Population 50- 25? / In of number of commas remaining ~253- Pig. 29. Showing groes colony mortality for total colonies chosen st stations 6. 6b and 8 at Iintergreen Lake. Kalansoe County in 1960. 1'he natural logarithm at the number of nrked colonies reninin; at each station is plotted against tip. 3 0 @'\Q \ 2.8 G) 7.9 “—5 ' 1 ll . \A 23} \A I A 2 o— \ IBI- .5 May— I WI [31 m;— G) A LG I .81— . (9 ~— .LI I— .2 L I l L I I L w I r: L I A L J J J L o ,0 lo 30‘” 40 V 50 (ac 7o Dax‘s G Sicilian 5 A?!“ 29, IQbO A Stafion 8 Aprzl 24, I450 E 5lotion 63 Max, Io, Who | In of number 0? Yamdm'mc] Cokm‘es -25;- Fig. 30. Showing gross colony mortality for total colonies chosen at stations 6, 5 and 13!) at lintergreen Lake. Kala-moo County in 1960. The natural logarithm of tin number of nrked colonies remaining at each station is plotted against We ‘ 1.6 r 2-‘4 dD—Q—G E 2.2 2.0 I-‘* ~ EI—m—EI A up 0 I0 20 30 Ho 50 Days Sia‘IIon Io Ma b, I950 Stanfion 3 APrII 21mm StaiIonIBB June 23mm 5196) -255- Fig. 31. Showing gross colony mrtality for total colonies chosen at station 9. Spril 29. 1960. at Wintergreen lake. Kalansoo County. The natural logarithm of the number or marked colonies renining at each station is plotted againet the c] co\on..es IhIh In of number Of remo 3.0 I 2.6 1.6 2.4 202 2.0 ha In of number of remoImnc‘ COIOh.|C$ Fig. 32. -256- Showing gross colony mortality for total colonies chosen at stations 2. 6 and 7 at Burke Lake. Clinton County. in 1960. the natural logarithm of the number of marked colonies renining at each station is plotted against time. L U3 El [3 1.0 "‘ \a . (3 I-S '- ‘CO I. A (3 El B .5 r \ 1 J _1 J I L 1 l J 0 IO 2% 3° ‘IO 50 Daxls ® Station 7 June l2) IQbO A Stallonz Max, 8,I9bo B Station 9 Maul 8, Hbo In of number 0f remqmmc‘ Co\on°ses -257- Fig. 33. Showing gross colony mortality for total colonies chosen at stations 2 and 4 at Burke lake. Clinton County in 1960. The natural logarithm of the nufier of marhed colonies re-ining at‘ each etation is plotted against fi-e ' 5°cb—©\ 2.5 . ®\® WI \A \B 5w \ \ o ' .2 ‘ I. 9 a; L I. J 5; D07 5 Slotfion 2 Apr” 27, Who Sta‘tIon 2 No.1 |,I‘lbo STQ‘Uon LI Max, I, Who Ell>® In of number “I remaking COIOn.\es -253; Fig. 3%. Showing gross colony mortality for total colonies chosen at stations S and 9 at Burke Lake. Clinton County. The natural logarithm of the number or narked colonies remaining at each station is plotted against time. 3.0 _Q _A\ 2.5 - 8\A-_—A—-A\A———_A A j I/ 1° ‘ wn—E—m———m———a l5 - \ 9 L0 r- \ DQYS Siafion ‘1 Apr” 27, Who Staflon b Apr" 27, who Staiion in Max, IE, ICIbo [390 09¢. SN. ucjfiI m £0;de a 9:: .3 :54 .n... £23m n 32.5 fix; j :0?de @ mrdfl on on cm or om 0N o. o a «I d d ‘ # a I1 fi 44!... fi I—I I4 1 fl ‘ m. E IQ U ~259- m: In O.N /®./I M.N 0.0. .alfl vegans 63....on ea nouvse dose as voids!!- eeaneueo venues «c hen-3n as» «o 53.253 «can»! I: .82 3 #53 .3933 .83 out... a. o 3. e 3933. .m 3.4 meeono weanoaoc 133 uou 5633.8! booaoo :93 Hogan .3 «h In o; number of remak‘nfi Colonres OJ»: «. >02. 00 COuaudvm a on... ._.~ 1...? h. Sufism 6 03¢. .w >6: m (Quantum Q L6G. 0m 0+. ON ON 0. O ow A g — 4 - ‘I u IQIfiI A 1 j m. I o._ o. a E G/ I h.— % /aIm In @I . .I.I.I.U./ E/Elll' L OM .15 «.36. 23.3 a 833. :8. a. manual... eeaooaco 3n!- uo hen-do on» no Influence "shoved can .82 3 95.8 «338 .33 3.25 a. no 3. n. .u .838. as neeome eeuocacc «33 new baud-0.8- hoodoe ocean mode—Eu .wn .mfi In of number og remalnlnc‘ Qo‘cmles In 0*" ‘I’ola' number of howpIdes SurvIvInc] —261- Fig. 37." Survivorship curve for 373 polypides or Plumatella regns. The natural logarithm of polypiacs sfiving is plotted against time. Data are from appendix tables 38 through 42 for Iintergresn and Burke Lakes. EDT- 5.5. \ .\ 5.0 .- II.sI- "I'OII' ' 3.5.. 3.0 *- 25 r . 2.0 - I5 I- ..O r- 0‘ \ \ x .5’ -- \‘ \ I I I J I I I I I \ 0 I0 10 so Ho 5 O Dan’s ~262- legend for symbols used in the growth. mortality and longevity tables Further discussion of these symbols appears in the text. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. X colony or polypide completely removed from substrate by a predator _ nunbsr + x designated number or polypides in colony remain. however portions or the colony are missing probably as a result of predation tips younger tips only of colony renmin. older central portion P0 fit. CI largely missing. probably as a result of natural disinte- gration. rolls of predation and disintegration colonies partly gone these syfiols used where relative were difficult to Judge colonies mostly gone colonies too mixed to count. indicates intertwining of sooecia; were too complex to permit an accurate polypide count. colony was both too densely entangled to count and also incomplete. colony counts so designated were approximate. error here not more than plus or minus ten. board or log (substrate) missing or had been pushed out into the lake colony removed by predator: syflol used only in longevity tables marked polypide was a victim of predation: symbol used only in longevity tables -263- TABLE 1. Growth data for each marked colony of Plumtella refine ‘ at station 1. 8urke Lake. Clinton 00.. 1960 Individual lo. of polypides in each colony from time or first colony observation to final observation. Months are indi- symbol cated by Rom numerals. lY—Z? V-l V-S v-15 V-22 V-29 R-l l 2 2 X a-z l 2 2 l X 2.3 I 1 2 2 s 3 1: Rod I. l 2 2 3 2 X R-5 I l 2 2 2 x R-6 I l 2 x Y-l : l 2 2 3 x T-2 ? 1 2 2 X Col ‘ l 2 z X 0-2 3" l 2 2 I Pol I l X 9-2 I 2 2 4 x RA-G l 2 X -264- TABLE 2. Growth data for each marked colony of Plumatella repens at Station 2. Burke Lake. Clinton 60.. 1960. See legend opposite Table l for explanation of symbols. Individual no. of polypides in each colony from time of first colony observation to final observation. loathe are indi- symbol cated by Bonn numerals. IV-Z" V-l 7-8 4 I .4 0| V-22 V-29 1.1 r-z Y-S Y-4 Y-S Y-G YO? Y-B _ Y-9 1.10 Yell 1-12 Y-IS Y-14 Y- 15 1.16 B-l 3.2 0-1 0.2 R-l 3.2 3-3 P91 P-2 P-5 P-4 P-5 P-6 I 0.: HOGQGOQOOHQ HHNNHHHHN “-m'n HNHHHHHHNHHHNHHHHHHH to ”wumwuuwwuwuuwuwtouwseuuw >40 quuamcsouoancxo-NHNHNHHacI-csaconauoluuoo finnnxuxx H H H H aoeacoouoI-u 9265- mm 3. Growth data for each nrked colony of Plumatella ream at Station 3. Burke lake. Clinton.Co.. 1960. 5.. legend opposite Table 1 for explanation of symbols. w- o.“ \fi- .L‘.r ._ i Individual No. of polypides in each colony from time of first colony observation to final observation. lonths are indi- symbol cated by Roman numerals. 17927 791 V98 V915 V922 7929 '7195 71-12 71-19 ‘71-26 091 1 2 4 18 20 73 092 l 2 4 13 25 52 550' 1200‘ 1800* tips 093 1 2 4 8 25 71 094 1 2 5 10 31 61 TI 291 2 3 7 8 26 86 TI Y-z l 1 1 2 3 7 TI T93 l 2 5 10 22 x 394 1 3 5 9 31 38pg TI 795 l 2 5 9 10 34 TI T96 2 3 7 ll 36 75 TI 197 l 2 7 13 42 73 'TI T98 I 1 3 6 13 21 80 TI I 9-1 I 1 2 4 o 21 19 u I P92 ; 1 2 3 11 x 993 f l 2 3 14 25 141 TI 994 I l 2 6 13 18 431 TI R91 I 1 2 5 8 19 21pg TI R92 ; 1 .2 3 5 x R93 I l 2 2 x n-c ' 1 , 2 6 u 32 so I n! R95 2 3 9 15 45 88. TI R96 3 1 I 2 6 8 18 x 1 R97 i l 3 8 l7 1 R98 . l 2 5 9 31 67 1 R99 . l 2 5 9 16 ‘1 R910 I 2 4 8 16 22 x I R911 5 2 2 3 7 9 x R912 ‘ l 2 4 4 6 X 1 R913 , 1 2 7 9 30 70 X V R91 1 2 6 20 44 x 392 1 2 . 3 13 x 893 I l 3 7 36 73 X 394 . 1 2 6 21 46 X 395 I 2 4 8 32 67 1 R96 2 3 7 17 57 I x P95 i 8 29 103 280 450' 850‘ tips P96 7 14 44 I x ‘l-l 10 29 96 I262 630 TI ‘l92 8 15 23 TI 3694 75 300 600‘ lo 095 ‘ 4 30 77 x R191 27 95 190 tips I _I 9266- TLBLS 39(continued) Individual Io. ef polypides in each colony from.time of first colony observation to final observation. 'Ionths are indicated symbol by Roman numerals. ' 17927 V91 798‘7915 V922 V929 71-5'71912 71-19 71926 VII-3 lB-l 18 211 495x 5961 1392 37 120 tips tips R593 30 95 tips tips 9267- 1191.! 4. Growth data for each marked colony of Plumatellare rage at Station 4. Burke Lake. Clinton Ce.. nd opposite Table l for explanation ef syiols . vf Individual So. of polypides in each colony from time of first sole” observation to final ebservation. Ienths are indicated symbol by Ron nu-rals. 17927 791 798 7915 7922 7929 7195 1912 71919 71926 71193 S91 1 2 I 692 1 2 3 3 7 x 393 2 3 6 6 I 594 l 2 3 6 15 48 103 PC P0 PC tips 595 1 2 5 6 14 25K 64 X 596 1 2 7 ll 20 X 597 l 2 8 7 17 34 44! TI Til B98 1 2 6 S 23 121 163 1 B99 2 3 9 10 26 50 65X 75X 381 301 111 5910 l 2 3 3 7 X R91 1 2 3 1: R92 1 3 5 I 5 3 12 41 501 301 tips tips R93 1 2 6 4 I14 24 42 55 751 201 tips R94 1 2 4 4 2 1; 6 16 33 tips R95 1 2 S 16 I 15 171 1 R96 1 2 6 I 7 21 25 481 tips tips tips tips R97 1 2 S ll 13 171 I a-s 1 z 4 I s 1 1s: 2s 10: 151 tips tips 791 2 7 12 x ‘ 792 2 5 11 321 32 ' 141 11 x 793 2 5 6 21 88 201‘ tips 1 794 2 5 2 7 14! 71 tips tips 795 2 6 7 17 x , 796 2 5 6 6 15 ‘ 30 136 781 tipsi G91 2 8 12 I 27 391 no I 692 2 l 2092 7 7 17 1 P91 4 17 18 20 251 691 1 P92 21 76 I 5091 4 1 X 0.3 15 121 61 ILBLI 5. -268- Grant): data for each lurked calm or letena rczns at Station 5. Burbs Lab, Clinton Gen 1560. gee legend epposite table 1 for explanatien of synbols. Individusl colemy sy-bol Io. of polypides in each colony tron tin of first obsemtion to timl observation. by Rem murals. loathe arc indicated 117927 Y. 1 '98 V915 V922 V929 V196 V1912 71919 71925 P91 P92 P98 P94 P95 P96 P97 P98 P99 ~ P910 P911 P912 R91 R92 R93 R94 R95 R96 IP91 IP92 IP93 NNNNNNNNNNNN khnuuwuumnuu HOQNHuNNu OIONNDI-‘H " HNNN HMO! «NNGNN a: OHHN ONNGQO I NHH Q04 141 17 141‘ 181 VII-3 926 99 23 n. no“ a N «um MN.“ MN." “NH N 9 nah nan H3 Hon 0 n N..." Na KN as MN o v 7.— In In In on an a n N at: N 9 o n one 23 .3» 6:. SN 3 3 3 3 c To H 3n 9N an .- n 9.6 A H noon Non Na 0 v 0.6 u 3 a A a To N n o a use H N2. on 3 o a N4. H Nev on N.— n 9 .70 H. N N 30m H n N N and In a an an 3 mu m n N calm H N N n7: H N a Nana an. a no» «a an a m N a Sun a a «a an NN o n N N 0.7m N H3 5 N n N N and a 5N N5 5n 0 a n N a «on B a 3” 3 o a n N A N E. In In . . and no N o N N N can «on H03 E a n9 5 N o N a con In 99 o— 3 o N a «in a MS 3 on m n N and In N» 0N on o n N Nam In. In. a no 3 3 o a N and 0.7:» noun: 0N0: can: «.7: 9.: «Nu» NNo» 30> as» as» 5N3: f “i- doa‘. .3383.— naflom ha connoddsu as afloaoo . clone: .aouadtocao and: 3 3353.3 99.3 no 8:» so: 333 no: 5 2.39309 No .oz «3353.; .enoic «o 5.3.3335 you a ewe-a ”among doom: eem 1.03m 44 .oo nova—«no .33 3.39 3 8343 as 3&8 4.33.253 no ancaoc v3.3— noec you 33 55.6 .o 53 92709 73%" Nut MN» NNN Non NO» an 6N OH ha a» Neda» no» N. Rodd Mao 2H ova «on pm $9 H. _Mn 0A K M NO no 5N v» #01960» 01»- ulna 00». ”Ju- «1H- #1»! «In nun «no man c1» n1» .1» n1» NJ» as» odsunb ”IHHF uNIHP GHIHP wasHP “NIP Nash was» 00> ash NNJPH egvfl01 II“ I” 1|” .eacucluu ndlem ha voueoadaa end II“ \I" ill-IF! .noaveruoepo Anna“ on noavnpuoeno vegan no ea«v.ssuu hacaoo node «a eedumhaoa «e .ou "21.? hfisnco nesvdruuan Hi“ “I l ll‘lll} ¢3¢3§aT6 5nd. 92719 IABLB 7. Orenth.data for each narknd coleny of Plunntella repens at Station 7, Burbs Labs, Clinton Ce" 1960. as legend epposits Table 1 fer explanation sf synbel. Individual ls. ef pelypides in each ooieq frsn tine ef first ebscr- co1eny vation te final ebscrvation. Heaths are indicated by synbel Benn nunrals. 17927 791 796 7915 7922 7929 7195 P91 2 4 6 3 16 1 P92 1 3 6 6 14 ‘1'! P93 1 3 6 9 22 44 71! P94 2 3 5 6 13 1'! P95 1 3 6 9 16 39 1! P96 2 4 6 9 1 P97 2 4 6 7 1 P96 1 z 4 a 1 P99 2 3 5 9 26 63 1‘! P910 2 3 6 1 P911 2 4 7 15 1 P912 2 3 7 9 16 50 fl P913 1 2 4 7 14 37 1'! 71912 71919 71926 71193 711910 711917 091 16 34 171 121 tips tips 092 4 16 37 104 374 990 693 4 1 . 094 36 155 356 990* 2000' 22001 191 5 22 73 279 795 4601 192 6 19 l 193 4 15 39 122 390 1200‘ I94 3 11 39 156 547 1260‘ 195 3 7 19 {1 R91 3 6' 22 73 226 695 392 4 14 40 129 316 4601 693 6 16 51 162 510 P0 594 4 14 1 I91 1 4 13 44 155 436 I92 3 9 27 92 324 692‘ '93 3 13 27 94 303 2201 I94 1 3 41 1 - R91 1 3 13 41 134 1501 R92 5 14 60 1 R93 2 6 19 64 264 791 -272- I'kl'!’ H HN nun N M: an an 9.5 2:5 a: no» 39 3 S «A: . 8 o a... 2:». Non HNH Nu m3 H09 ON m N..- o» a A. 7n Moo No NN a n...— K EN... 3 9 N...— emdv ON 3 N . mom 3: 32 a...» no... 3 a 9 7: M9.— c N . Nob H 9A a an! a ... A 3 M 9a a n . Nlo 2:» 8 8 E «2 9 3 _ To a 2:5 no» as no» 3 S 9 N 7- H a: o o a Ntu N Ru 3 o n n Nun an on 9N N . n J a...» H No NH 9 n N.» H 03 3 3 9 .7» 9Nou= Nana: 07H; noun» 3ng 0.7: N7; an: 3:» NNub 07> nah ac - .3935: n'om h: 934315 on: baoaoo 39.—o: .ncquc-no Neda 3 53.5.3vo 9...: no clap no.8 Naoaoc node an 39.33% No .cu ”3995!: . . .931». no 53363: you a canon evaconmo doomed ecu .co 633.3 .893 c856 .m 533» an anon: 6:33: No buoaoo 9..ch node you .829 5.5.8 .o an: 9273- 1ABLI 9. Growth data for each marked colony of Flu-atella rcpgns at Station 68, Burks Lakn. Clinton 00.. 1960. gee lcgcnd opposite Table l for explanation of symbols. Individual No. of polypides in.each colony fron.tine of first observa- colony tion to final observation. Ionths are indicated by Ronan symbol numerals. 791 796 7915 7922 7929 ‘7195 71912 71919 '71925 R91 1 2 4 14 43 166 460 tips 1 R92 1 2 5 19 62 205 tips R93 1 3 7 20 52 167 P6 R94 1 3 1 191 1 2 4 16 50 1X . 192 1 3 6 23 67 169 tips 193 1 2 6 6 1 I91 1 2 5 17 59 161 1201 tips .1 ‘792 l 2 5 1 ‘793 1 2 4 15 36 301 ‘794 l 2 5 16 1 P91 1 3 7 24 62 213 P6 P92 1 I 2 5 13 so I 251 1 P93 2 5 1 P94 1 2 5 12 1 P95 2 4 17 57 173 P6 tips 1 691 1 3 9 33 106 266 211 692 1 3 7 19 1 R93 1 3 9 23 51 1 S94 1 2 6 X 091 2 4 14 43 136 , 701 101 1 0.2 1 a 11 40 112 f 351 tips 093 2 5 6 tips: 1 694 2 4 12 36 ; 126 tips 695 2 5 14 36 102‘ 131 1 1191 2 4 12 44 111 tips n92 ' 2 4 11 so 1 - u—1 { . 2 7 24 sx 1 I192 P i 2 e 16 j 116 92749 tiBLl 10. Growth data for ouch narkcd colony of'Plunatella ropgns at Station 9. Burk: Lako. Clinton 0o.. 1960. 5;; logpnd opposito Table 1 for expaanation of symbols. m: Individual lo. of polypides in each colony fron.tino of first observa- colony tion to final observation. Months aro indicatod by Roman snhl wank. 17927 791 7915 7922 7929 7195 71912 71919 4 I a a-1 n—2 n-3 3-4 2-5 #6 2.7 . 393 7 14 I unc- Fm bu FR 5“ L“ F“ F“ W" k" 2.19 1 hm l 51 ' 52 53 W4 w 55 F1 F2 F3 F4 F1 o-2 i _——w-——v—‘ NNNNNNNNNNNNNNNNNNNN «a No 14 I NNNNquunuwnuwunuu«wuuwun NHuN H Nanak «an Hknumu H unquphpaumNHNONNOONNuaHHHHHHO umuaod oukag§ a x xxx 92759 11613 11. Growth data for each mrked colony of P1unte11a refine at Station 10, Burke lake, Clinton 0o.. 1960. 3;. legend opposite Table 1 for explanation of ynbols. Individual lo. of polypidee in each colony fron tine of first observation colony to final observation. Months are indicated by Hanan nuncrals. synbol 17927 791 796 7915 7922 7929 7195 R91 1 1 X ’ R92 2 1 P91 1 2 2 1 P92 1 3 3 7 4 1 11513 12. Growth data for each nrbd colony of Plumtella m at satin 11. Burk. 11h, Clinton Gas. 0 - Individual lo. of polypides in each colony from tins of first observation colony to final observation. Ionths are indicated by Ron numerals. sywol 796 7915 7922 7929 7195 I91 2 2 9 1 I92 2 3 1 I93 5 6 1 P91 2 4 10 1 P92 2 5 12 i 1 P93 . 2 1 P94 3 5 16 1 R91 4 6 1 R92 2 3 6 I 191 2 3 9 1 192 5 6 l 193 5 5 1 691 6 X 692 { 3 7 20 1 R 3 ll 1 14313 13. Growth data for each lurked colony of Plumtella rezns at Station 12. Burk. 14b. Clinton 00.. 1950. Individual lo. of polypides in each colony fron tins of first observation colony to final observation. 10an are indicated by Ron nunerals. sylbol ‘ ‘ 796 7915 7922 7929 7195 P91 3 5 7 1 091 2 4 X 692 2 3 7 1 191 2 3 1 192 3 5 5 X R 2 3 3 4 1 P92 5 15 1 B91 4 6 1 592 i 2 2 X ‘ 92769 11.31.! 14. Growth data for each nrked colony of Plulntella remns at Station 13. Burke Lakn. Clinton 00.. 1960. §;e legend opposite Table 1 for explanation of symbols. _" w I‘M-.1 Individual Io. of polypides in each colony from time of first observa- colony tion to final observation. lenths are indicated by Roman symbol numerals. 791 796 '7915 7922 7929 7195 71912 71919 71926 191 1 2 6 20 X 192 1 2 4 9 30 102 P6 195 1 5 7 22 57 146 BOX 194 1 2 4 10 1 195 1 3 5 14 39 1 991 1 2 5 10 26 63 III R92 1 2 6 17 54 1 193 1 3 6 21 67 401 .1 R94 1 2 4 10 29 1 P91 1 ' 2 4 14 35 111 741 P92 1 2 4 12 26 61 256 510‘ 2-3 1 2 5 14 37 99 274 3001* 1 P94 $ 1 2 3 8 23 1 b 691 l 2 5 16 47 162 1201 1 c-z V 2 4 11 34 so 278 160‘ L 693 2 4 7 11 I , 694 1 2 6 17 61 1 I91 1 2 6 20 66 201 1 v92 1 1 2 5 23 99 tips ‘793 1 3 6 221. 1 77-4. ' l 2 4 9 .2e 1 171912 71919 71926 ‘71193 711910 '711917 711924 691 k 1 3 14 51 166 467‘ 1 n-z * 3 1o 32 115 364 11359 S93 3 15 62 226 751 694 3 7 23 67 291 765 695 5 16 1 -277- 11913 15. Growth data for each narkcd colony of Plumatella re ns at Station 14, Burke Lake. Clinton Co.. 1960. 5;; 1egpnd Opposite 1ab1o 1 for explanation of symbols. Individual lo. of polypides in each colony fron.tinc of first obser- colony vation to final observation. lonths are indicated by symbol Roman numerals. 17927 791 796 7915 7922 7929 7195 71912 71919 71926 691 1 2 5 9 25 66 271 1401 .1 S92 1 1 2 5 13 34 95 1201 tips 693 1 2 4 1 R94 1 3 6 15 39 69 tips 695 1 2 4 14 33 61 293 605‘I 191 1 2 5 10 30 66 190 505‘ tips 1 192 1 2 6 20 1 193 1 3 ll 24 62 1 194 1 2 4 11 25 69 401 195 l 2 3 7 1 I91 1 l 2 4 1 R91 2 4 7 16 1 R92 2 3 5 13 26 77 1101 R93 2 4 6 19 52 144 326 ‘1651 R94 2 5 6 21 451 1 R95 2 4 1 R96 2 5 14 39 96 1 R97 2 4 12 32 101 1111 tips 92789 ILBLR 16. Growth data for each marked colony of Plumatella repens at Station.2. Burke Iain. Clinton.6o.. 1959. e legend apposite fable 1 for explanation of symbols. Individual lo. of polypides in each colony fro; time of 21m observa- - colony tion to final observation. lonths are indicated by Ronan sylbol numerals. ' ‘71914 71920 71192 71199 11921 Dr 44 In .1 Dp 5 l4 1 3p 36 30 1 11653 17. Growth data for each marked colony of Plunatella repgns at Station 3. Burko Lake. Clinton 00.. 1 6 e Individual lo. of polypides in each colony from.time of first observa- colony tion to final observation. Ionths are indicated by Roman symbol numerals. 7917 7924 ‘7931 7196 71914 ‘71920 R 2 6 20 55 191 1421 G 2 7 26 79 267 1 R 4 17 49 137 540 1 1 2 6 22 41 97 ILBLS 16. Growth data for each narkod colony of Plumatella repens at Station.4. Burke lain. Clinton.co.. 1 59. Individual lo. of polypides in each colony from time of first observa- colony tion to final observation. Months are indicated by Roman symbol numerals. 71920 71192 71199 711921 711926 711197 7111914‘7111924 1195 11920 iy 6 34 1 5g 2 10 21 61 31 6p 2 13 32 301 251 ng 2 10 1 Rpr 4 27 61 1 P 2 12 44 261 1101 Pb 3 26 601 1 6g 263 630 Hp 17 121 It 4 15 52 263 710 Po 2 9 32 166 902* 1 R 1 3 16 131 1 1 1 3 21 206 1 -279- IABLB 19. Growth data for each snrloed colony of Plunatella re ns at Station 5. Burke Lake. Clinton 00.. 1 5 . ee loge opposite fable 1 for explanation of symbols. Individual lo. of polypides in each colony from tins of first observation colony to final observation. Ionths are indicated by Bonn numerals. symbo1 7924 7931 7196 71914 71920 71192 71199 711921 711926 711197 236 c 19 #32 125 155 x Ryv 6 26 104 129 204 1 G91 1 4 11 31 46 1 G92 1 3 6 26 72 1 191 5 15 51 161 345 401 D 2 6 15 96 257 6901 1101 no 5 2 5 14 61 226 1141' 471 171 P 2 6 21 60 295 3161 11618 20. Growth data for each nrbd colony of Plumtellare rensp: at Station 6. Burke Lake. Clinton 00.. 195 . if Individual lo. of polypides in each colony from time of first observa- colony tion to final observation. Months are indicated by Ronan , sysbol numerals. 7-31 71-5 ] 71-14 71-20 71192 0c 19 59 T 194 1761’0 1 11618 21. Growth data for each nrked colony of Plumatella refine at Station 7, Burke Labs, Clinton 00.. 1 5 . ‘Individual lo. wof polypides in each colony from time of first observation colony to final observation. Ionths are indicated by Ros-n nunerals. symbol 7924 7931 7196 71914 71920 71192 71199 711921 7119261711197 6 16 51 I 1 30 1 6 31 . 36 1 I 21 1 P 2 6 42 136 601 R 2 13 36 174 P6 1 1i 5 26 241 121 1 9280- tiBLl 22. Growth data for each marked colony of Plumatellam at Station 6. Burbs Lahe. Clinton 00.. 173—T. 5 . eel "3.3. opposite Table 1 for explanation of symbols.. Individual 10. of polypides in each colony from time of first observa- colony tion to final observation. lionths are indicated by Rosnn synbol numerals. 7924 7931 7196 71914 71920 71192 R 2 7 39 162 1251 0 2 S 34 151 500‘ 1-20 1-29 11-7 n-1s 11922 n-zo xxx-c Sb 7 12 3 3 1 0g 3 4 5 3 2 2 1 1 2 4 7 5 5 3 1 I 1 1 R 3 3 1 P 4 6 10 4 4 l 1 Br 3 4 6 5 2 2 1 1o 2 4 6 3 3 l 1 Pg 2 5 6 6 3 2 1 Py 3 5 1 92819 TABLE 23. Growth data for each lll'bd colony of Plumatella regns at Station 3. Wintergreen Labs. Kalamasoo 50.. 1960. e legend opposite fable 1 for explanation of sysbols. V viiiTv—iduval 707.10ffipolypides in each colony fron tins of first observa- colony tion to final observation. lanths are indicated by Bonn symbol numerals. 17929 796 7913 7920 7927 7197 71914 71923 691 1 2 5 13 37 1 R92 1 3 6 1 191 1 2 6 19 49 161 1 192 2 5 13 57 169 1 193 2 6 16 61 192 701 1 194 2 5 17 59 200‘ 437 tips 1 091 2 5 12 47 154 1 G92 1 2 5 16 62 246 651 1 1161.1 24. Growth data for each marked colony of Plumtella rezns at Station 5. Wintergreen Labs. Kalamasoo 00.. 1960. W Individual lo. of polypides in each colony fron tins of first observa- colony tion to final observation. Ionths are indicated by Bonn synbol numerals. 17929 796 7913 7920 7927 7197 71914 71923 091 2 5 16 65 125 1 R91 1 2 5 19 50 1 R92 1 3 9 36 95' 1 R93 2 5 13 77 226 1 R94 1 3 6 22 60 1 R95 1 2 7 21 45 1 191 2 6 17 70 1201 1 192 2 4 14 m 1 193 1 3 9 1 194 1 3 11 56 177 1 195 1 l 3 15 40 1 791 2 5 17 141 42 1 792 2 4 7 33 95 1 I93 2 5 13 32 60 61 1 W94 2 6 21 76 1 190 1 2-1 3 a 17 67 s 1101 } x 691 2 6 23 60 I 85 1 ’ B92 2 5 > 16 64 , 216 i 741 1 1H! 1 2 6 20 I 64 K tips 1 3+6 1 3 7 23 x } P92 1 3 11 116 ID 1 P93 1 2 1 1 P94 2 3 16 76 1 P+R 1 3 8 I, 35 91 X 8+1 1 2 6 g 46 701 321 1 __ P95 1 2 ; 11 1 -232- 11613 25. Growth data for each mrked colony of Plumatella re ns at Station 6. Wintergreen Lake. KalamazoWOfi legend opposite Table 1 for explanation of symbols. Individual 110. of polypides in each colony from time of first observa- colonw tion to fiml observation. Ionths are indicated by Ronan syflwl numerals. 17929 796 7913 7920 7927 7197 71914 ‘71923 71930 691 4 6 19 60 206 2501 2401 1 692 2 5 13 35 110 1001 tips ‘1 P91 1 2 5 20 201 1 P92 1 2 4 7 30 tips tips 1 ’P93 1 2 ,5 25 90 tips tips 1 P94 1 z s 23 74 no no 5 1 R91 1 2 4 12 22 31 1 R92 1 3 6 ll 20 61 tips ‘ 1 G91 1 2 5 ll 32 tips tips ' 1 R93 1 3 12 23 PG no 1 R94 1 2 6 24 PG I0 1 W91 1 2 5 III l0 ‘1 ‘ W92 1 4 16 59 III In 1 G92 1 - 3 12 36 116 tips _ 1 693 1 3 20 30 tips tips 1 094 l ,4 10 1 191 1 5 26 60 276 1201 1 192 1 4 23 tips tips tips . 1 193 1 3 12 43 191 tips 1 794 2 5 15 45 242 tips 1 1191 6 1 1192 16 1 1193 l 4 1 9283- 71613 26. Growth data for each lurked colony of Plumtellare nsat Station 66. Wintergreen lake. Kalansoo Co.. 1960. gee legend opposite Table 1 for explanation of symbols. —_-— Individual lo. of polypides in each colony fro: tins of first observa- colony tion to final observation. Ionths are indicated by Bonn syabol murals . 796 7913 7920 7927 7197 71914 P91 1 4 13 1 P92 1 2 6 1 791 l 2 9 1 192 1 4 16 71 1 G91 1 4 14 1 692 1 2 6 33 1 693 1 3 12 1 694 l 4 15 1 991 l 3 ll 51 1 692 1 3 9 1 R91 1 3 10 34 1 R92 1 3 12 , 1 P93 10 1 P94 4 1 793 4 20 1 194 1 1 R93 7 1 R94 4 1 I91 5 1 I92 11 19 71 I93 3 1 I4 . 2 15 1 7191 1 6 1 92849 11613 27. Growth data for each nrked colon of Plumtella re ns at Station 7. Iintergreen Lake. Kala-asoo 55.. 1960. e legend opposite Table 1 for explanation of symbols. —‘ Individual lo. of polypides in each colony frontine of first observa- eolony tion to fiml observation. Ionths are indicated by Roman sywol numerals. 796 7913 7920 7927 7197 091 1 3 7 21 1 092 l 1 093 l 1 G94 1 1 G95 1 1 G96 1 1 697 l 1 096 l 1 1 R91 1 1 R92 1 3 6 1 71930 71197 711941 0191 2 3 1 Y‘.1 1 I I 9285- 71618 26. Growth data for each nrksd colony of Pluntellaro at Station 6. Wintergreen Lake. Islansoo 00.. 1960. ronsg; legend opposite Table l for explanation of symbols. Individual lo. of polypides in each colony fron tine of first observation colony to final observation. Ionths are indiéated by Bonn minerals. syflol rr—rvw 1' v 17929 796 7913 7920 7927 7197 71914 71923 71930 71197 691 l 2 6 37 116 496 701 tips tips 1 092 1 2 1 093 1 3 6 20 70 201. 1 094 1 3 1 095 l 2 5 13 46 161 tips 1 696 l 2 4 15 29 41 1 R91 1 2 5 35 136 1 R92 1 3 9 26 1 R93 1 3 1 R94 1 2 5 19 60 ’ tips tips tips 1 R95 1 2 3 22 101 1 R96 1 2 10 1'! 40" 501 tips 1 R97 1 3 7 1 R96 1 3 6 33 105 201 tips tips tips 691 l 3 16 53 191 tips tips 692 1 3 l4 1 791 1 4 711 1 792 l 3 16 tips 1 0192 2 6 29 1 6194 2 10 36 141 1 B93 9 1 694 9 1 P91 10 1 P92 5 3 1 P93 6 l4 1 P94 4 1 6191 l l 1 66192 1 1 0193 l 1 9191 l 1 6192 l 1 6193 5 1 R191 2 1 R192 1 1 1 92869 71613 29. Growth data for each lurked colony of Plumtella ream at ltation 9. Wintergreen lake. Kala-asoo 50.. 1560. e legend opposite Table l for explanation of synbols. Individual 10. of polypides in each colony from tins of first observation colony to final observation. Ionths are indicated by Ron minerals. symbol 17929 796 7913 7920 7927 7197 71914 71923 71930 691 1 2 1 092 1 2 1 G93 1 2 1 094 l 3 1 095 1 2 1 096 1 2 1 097 l 1 3 6 26 56 1 696 1 ' 2 6 19 30 1 099 l 2 5 7 l9 1 6910 l 2 4 26 36 1 l 6911 l 2 3 9 26 1 i 6912 l 2 4 13 26 1 i 6913 l 2 3 ll 20 1 -. 0914 l 2 4 l4 1 691 l 2 5 20 53 1 692 l 3 6 27 69 1 B93 2 5 12 Peg1 . 791 l 2 6 24 1 792 l 3 10 1 793 l 3 12 41 137 1 v—1 9 1 4 19 co 1 I92 1 3 13 42 1 I93 1 3 1 7191 l 1 11.2 r 12 1 P91 5 1 92679 11616 30. Growth data for each aarted colony of Plu-atella re as at Station 10. lintergreen labs. Kalansoo 60.. 1960. e legend Opposite Table l for explanation of synbols. ' :I: m Individual lo. of polypides in each colony fro. tin of first observa- eolony tion to final observation. Ionths are indicated by Bonn synbol numerals. 17929 79c 751: 7-20 7-27 71-7 71-14 391 1 2 3 II II. see 292 l 3 6 23 55 355 2“ 293 l 3 2 1. “* I94 1 2 - 5 12 1 ‘7‘ R95 1 2 5 16 1 1 9“ ans 1. s x 1 999 0-1 1 2 e 21 as i 304 ... 0-2 1 s s 23 1 I ... G93 1 2 5 l9 1 ‘2‘ G94 3 5 21 50 220 635 2“ G95 1 2 5 16 50 252 9“ 095 l 2 5 15 52 1 *** 791 l 2 4 ll 1 ‘9‘ 792 l l 4 ll 1 '2‘ 793 l 2 2 9 1 2“ 194 1 3 10 29 62 i 437 *** 795 l 2 5 17 53 343 ‘2‘ 795 3 7 17 53 202 439 ‘9‘ 691 l 1 2 3 9 1 2" 692 l 2 5 1 ‘2‘ I93 2 4 3 {1 2“ 694 1 1 3 9 34 175 2" B95 1 2 4 ll 35 146 2" 395 l 3 6 ‘1 *“ P91 5 20 .1 9“ P92 2 5 30 152 2" I91 1 2 7 42 '7‘ I92 1 3 ll 61 2“ 92889 7161.6 31. Groetb data for each narked colon of Pinnatella reggns at Station 11. Iintergreen labs. Kala-asoo 30.. 1960. legend opposite table 1 for explanation of symbols. Individual Io. of polypides in each colony fron tins of first observa- coloq tion to final observation. Months are indicated by Rona syabol numerals. 17929 796 7913 7920 7927 7197 71914 R 2 5 10 ll 30 1 7 2 5 12 47 209301 1 P 2 6 16 70 246 1101 tips 0 2 5 9 26 63 1 l 2 5 12 41 139 501 1 71923 71930 71197 711914 691 l 1 692 1 1 6191 1 4 11 1 0192 1 5 1 7191 2 6 1 R191 1 1 P191 1 1 7191 5 1 7192 6 1 6191 6 1 6192 3 1 92899 2161.6 32. Growth data for each nrked colony of Plumatella re ns at Station 12. Wintergreen Lake. 111“!” 50.. 1960. e legend opposite hble l for explanation of synbols. Individual lo. of polypides in each colony from tins of first observa- colony tion to final observation. Ionths are indicated by Ronan syabol nunerals. 17929 796 7913 7920 7927 7197 71914 71923 71930 71197 711914 R91 1 2 7 23 76 420 1200‘ 1 R92 1 3 6 20 66 463 2251 1 691 l 2 4 21 . 60 151 ‘1 692 1 2 6 17 53 305 962 2101 1 P91 1 3 6 26 69 365 695 3001 1 P92 1 2 7 25 64 266 1101 261 1 091 17 1 R91 1 1 R92 5 7 5 1 R93 1 1 R94 1 1 191 £ 3 1 792 6 9 1 793 4 1 1.4 2 1 x l 791 L 2 3 4 1 77-2 1 c f 4 x 7161.! 33. Growth data for each nrked colony of Plumatella regns at Station 13. Wintergreen Lake. [slams—”00 06.71? . Individual lo. of polypides in each colony fron tins of first observa- colon tion to final observation. Ionths are indicated by Bonn synbol numerals. , 1792.9 795 7913 7920 7927 7197 691 2 5 6 16 20 W" 692 1 y 2 10 31 1 7" R91 1 2 7 12 10 4*“ R92 1 3 1 9” P91 1 2 1 7" P92 1 2 6 31 42 7“ 9290- 71613 34. Growth data for each narked colony of Plumtella re as at Station 135. Iintergreen lake. Kalanasoo 60.. 19 . e legend opposite Table l for explanation of synbols. Individual lo. of polypides in each colony fron tins of first observa- eolow tion to final observation. Ionths are indicated by Rm synbol nunsrals. 71923 71930 71197 711914 711921 711926 R91 1 2 1 R92 1 2 3 10 71 R93 1 2 4 14 61 R94 1 2 2 1 791 2 1 792 l 2 1 P91 2 5 10 36 tips P92 3 5 6 29 321 P93 20 62 51 1 P94 5 20 1 793 2 3 1 794 l 1 I91 1 2 1 I92 2 1 G91 1 2 L 1 092 3 2 5 1 693 2 3 1 694 l 2 7 41 1 71613 35. Growth data for each marked colony of Plumtella rogue at Station 14. Wintergreen labs. Kalamazoo 60.. 19 . M _fi— Individual lie. of polypides in each colony fren tins of first observa— colony tion to final observation. lonths are indicated by Benn symbol minerals. . 17929 796 7913 r M 1 s x 6 l 3 1 0 l 3 1 I l 3 1 92919 71613 36. Growth data for each marked colony of Plumtella ream at Station 15. Wintergreen lake. Kalamazoo 50.. 19 . See legend opposite 7able l for explanation of synbols. Individual lo. of polypides in each colony fron tins of first observa- colony ~ tion to final observation. lonths are indicated by Ronn symbol nnnerals. 17929 796 7913 7920 7927 7197 71914 691 l 2 7 32 112 171 1 I91 2 3 4 1 P91 1‘ 3 13 54 P0 1 7161.6 37. Growth data for each sarbed colony of letellare rezns at Station 16. Iintergreen lake. Kalasnsoo 0.. 5 Iiividual 10. of polypides in each colony from tins of first observa- colony tion to final observation. Ionths are indicated by Roann sysbol mnnerals. _ 17929 796 7913 7920 7927 7197 71914 71923 71930 ' 7-1 1 2 a 22 so :75 505p; x 792 1 2 6 25 62 312 720 tips 1 793 l 3 6 . 23 56 265 1 691 l 2 7 20 63 1 092 l 2 6 13 44 601 1 093 l 2 6 l7 1 094 l 2 1 P91 1 3 7 22 49 1 P92 1 2 9 16 53 327 1 P93 1 2 5 16 51 , 235 651 1 a a n n c a a H n A . N N m a m a A N o _m a d o 2 «a . a a a . a a 2 a N .— n n A H u a N N m a H a n v u a H u . s- 2.--. 9:11... : ---... -l..-.. u a u N n » Sn u n u e u 5 mm o No A N mm H a. a H H N 0 ¢ M H H A n o o n u - H. a u. a H A n v v o o o." u . Ho N v I m 6. a n n n E 9.. a H N h P n a mom a In: N o o H: b... no a a a a no” A n v a a» an N u N H n N o a N cum H H a N N N a N H a H H N a an m e a N a .2": 0 an m h... n n a o no N a u an a: a n H o o o 686.. a 3.5 and «mud? and; THE» 87:» SA: «.5» «73> 37H» 97: on: S.» . 37:55 in hp :21»- .3865 333:3 9:. :38: .83236 in: 3 man...- a.. 33 8.6 33.56 o»: «a .o- 31.5... 833. .82 .358 2333 .83 82.6 no 3333. est-322. 5.. a .3816: no 331.1 68...:- noso non 83 33323 .3 33 N H H H H H .H Nu m n a No H I H H H H u .... a a a H a a _ 9 hub H Hr “~71th + F» in - 0.. N H N N nan H N a a an. v .. N N N a a a . may H H N e v n -. 8 No N .3 No H N e a a n» H N v a. 33 H N o o a o o o a mNIHN NNIHN mHsHN thH «NIH ONIH CHIN aNsNH HNIHH DOHH thHHH> uHsHHHP .aHeaeann 03m .3 03333 eHoihe nee-no one 23.—o: 5033.330 Hana ca mafia- we even so: eevahHoa sp.—H no .0: evHEHHeN 833» < 5 lulllll .3: :09 dean—«Ho :83 3.25; 30.33- oeosnuHeev as an“: sHHengm «o evahHoa 603%. goes. aoh 83v Daren—SH .3 53 -294- . a a o .H 3 N H H H N 4% AH HN N N m OH H H N m H m u a N N N N N v N N N v a o o o a .H‘ H H n v w c c w H. HM ‘ iflaglllll+l mi a.-- N H N n n o B N N m H. H. o a a L Hf - kg ‘ -HLT3m 3 PH Lrlomz. - n v H H N a _v v a p m mu m o .H N , 5H H H H «.6 HR H H H Hua HM H H H NI» NM H H H H H.» KN H H 00m MN H H H H and NM N H H H H «um an H H H H H and HR H H H H Nam NH H H H Hum H 3.5» muHF NuHH> eNoHloHag N7: 9.: ouup .3.» 24 on» H.» 5-5 .quuoiHE as up c3333 33!». hoe-HE .3933 83.3 P:- nfinol .HSHoEo-no H33 3. wait. no 346 not novahHon obHH uo .on .83 :8 £358 .33 3.5.. .838. .532... a. Sum... .2833 Ho ovHenHoa «on»! H3. .5 86 krona: .3 53 —295- 14313 41. Longevity data for ouch lurked polypide of lejaollc Lop.” at (1011th nations. Hinton-groan Lara. humane 00.. 1969. Station Polypide lo. or 117. polypides from «to of lurking to {in} number ”welt obsomuon. lanth- uro indie-mod by loan meals. “-3 VII-1'! Vii-2? VII-4 VII-24 3 a 4 3 3 1 x 4! 4 2 1 x 3 ”-22-" 3 1 x 7 BIG? 4 2 2 2 x e 4o 5 4. 2 2 1 4! 4 4 3 1 I 9 P 2 1 x ' R 2 2 1 x I 4 4 1 I 10 R 2 2 2 x P 4 2 2 1 I -295- 0H N N n n m u H H H N N «H u a o o .H a n N 2 k H N H. o s u n N a N N N H H H H H o a N. u H H. H. N a a H N N N n N a H N...HH> 8-; 3.: «7H» .3; 5-» 8..» NH-» 3.» NN..>H {Hausa 533 up 63:33 0.3 .Hopflh. .3353 .58.. .8353... H8: 2.. 95.:- N... 33 ufiu 33935 BHH N. 6. 25.5.3 .833. .003 300 33H: .083 5233:: 63.23.. «383.3 3.3 32mm .2315qu No 833.3 «at... so: 28 33 3?.»an .N¢ and 1:51. 43. - Inter tenant-urn taken at Iintorgroon Lake and Burke 14b on the -297- 4020 when duh were oolloohd. lintorénoyhko, £011.31» 60.. 1960 IV-29 V06 V-lfi V-ZO v.27 VII-7 “-14 “-23 I ".30 VII-7 I‘m-14 11°05 16°C. 14° C. 24°C. 21° C. 24° 91 28°C 0 29°C.| 28° 0. 29.5° C.L50° C. 50m mm. Clinton 05.. 1959 v-21 J VI-C | 71-14 v1-20 VII-2 VII-9 VII-21 VII-28 n11-7[nII-1slnn-24 24°c.[2600. 25°C. 23°C. 29.2°C. 29°C. 31.5°C. 50.5°C. 51°C.E9.5°C. 31.5°C. :1-6 LII-212149 £10 I 1.20 x-zswln-v n-15 n-zz n-zo XII-6 50°C.lzo°c. 22°C. 17°C.I15°C. 12.5% 5.5%. 8°C. 5.5°C.5.5°C. 4.5°C. Burke Luke. Clinton 00.. 1960 No2? I v-1 v-C v-15 v-zz v-ze VI-5 ”-12 1 “-19 1?.6°C.!14.6°C. 15°C. 15°C. 20.5°C. 25:0. 26.5°C. 26°O.128.5°C. 171-25 VII-2 fill-9 VII-16 28°C. 25.5°c. 29°C. 30°C. LITERATURE CITED Abricoesofr, G. 1927a. To the knowledge or the Fauna (Bryozoa) of the Caucasus. Ruse. Hydrobiol. Zeitachrift, Saratov, USSR. 6:84-92. . 1927b. Uber die Sneavaseer Bryozoen der USSR. Comptee Rendns Acad. Sci.‘URSS. 19(A):307-312. Allman, G. J. 1856. A monograph of treehevater Polyzoa. Ray Society, Londonxl-119. Annandale, N.'l909. Preliminary note on a new genus or Phylac- tolaematoue Polyzoa. Rec. Ind. m5. 33279-280. . 1910. IV. Materials for the revision of the Phylac- tolaematoue Polyzoa of India. Rec. Ind. Ina. 5:37-57. . 1916. Polyzoa Entoprocta and Ctenostomata. Mom. R. Asiatic Soc. Bengal 6:15-35. . 1922. Polyzoa in the Colombo waterworks. Spolia Zeylanioa 12:207-209. ' Borg, F. 1936a. Snr quelquee Bryozoairea d'eau deuce Nord- Africaine. Bull. Soc. Hist. Natur. Afrique du Nord . 1956b.‘Uber die Suaswasaer Bryozoen Afrikae. Senken- ergiana 18:20-36. . . 1941. Uber die Sueewaseer Bryozoen Schwedene. Zool. Bidrag, Uppsala 20:479-494. Borodin, N. 1928. Notes on Pectinatella magnifica. Zool. Jahrb. Syet. 0:01. 542487-49TI Braem, F. 1890.'Untereuohungen uber die Bryozoen dea sueeen waeeere. Bibliotheca Zoologica, Kaeeel. 2 Heft VI. 1-134. Brien, P. 1936. Reproduction aeexuee do: Phylactolematee. Men. Mus. Hist. Natur. Belgique (2), faec. 33569-625. . 1953. Evade our lee Phylactolematee. Ann. 800. Roy. 2001. Belg. 84:301-444. Brooks, C. M. 1929. Notes on the statoblasts and polypides of Pectinatella magnifica. Proc. Acad. Nat. 801., Phila. EI :127’3410 I Brown, C. J. D. 1953. A limnologioal study of certain fresh- water Polyzoa with special reference to their stato- blasts. Trans. Amer. Micr. Soc. 52:271-316. -298- ~299- Cain, A. J. 1954. Animal species and their evolution. 190 p. London: Hutchinson House. - Cunnington, W. A. 1920. The fauna of the African lakes: A smudy in comparative limnology with special reference to Tanganyika. Proc. 2001. Soc. London3507-622. Dahlgren, U. 1934. A species and genus of freshewater Bryozoan new to North.America. Science 79:510. Davenport, G. B. 1900. On the variation of the statoblasts of Pectinatella maggifica from lake Michigan at Chicago. Killer. Nature 3 -968. . 1904. Report on the freshswater Bryozoa of the United States. Proc. 0. 3. Nat. Mus. 27:211-221. do Guerne, J. 1888. Sur la dissemination des organismes d'eau douce par les Palmipedes. Soc. Biol., Paris 82294-298. Dendy, A. 1906. Occurrence of Fredericella sultana in New Zealand. Trans. Proc. New ZeaIand Inst. 39:221-222. Despax, R. 1926. Bryozoaires rencontres dans quelques lacs Pyreneens. Bull. Soc. Hist. Nat. Toulouse 54:18-23. Eggleton, F. E. 1952. Dynamics of interdepression benthic communities. Trans. Amer. Micr. Soc. 71(3)2189-228. Fetterolf, C. de la mesa. 1952. A population study on the fishes of Wintergreen Lake, Kalamazoo County, Michigan. 'Unpublished M. S. thesis, Mich. State Univ. 127p. Forel, F. 1884. Le faune profonde.des lacs suisses. Neue Denkschr. Allg. Schweiz. Gesellsch. Gesamt. NaturwissenNXN 29:1-234. Geiser, S. 1937. Pectinatella ma ifica Leidy an occasional river-pest n owa. old and IEboratory pp.65-76. Goddard, E. J. 1909. Australian fresh-water Polyzoa. Proc. Idnn. 800. N. 8. Wales 34:487-496. Hancock, A. 1850. On the anatomy of the freshpwater Bryozoa, with descriptions of three species. Ann. Mag. Nat. Hist. 5(2):173-204. Harmer, S. F. 1913. The Polyzoa of waterworks. Proc. 2001. Soc. Londona426-457. Hastings, A. B. 1938. The Polyzoa. Ann. Mag. Nat. Hist. 11(2):529-535. ~300- Houghton, Rev. W. 1860. Note on Fredericella sultana being found in the winter. Ann. Egg. Na E. Hist. 3(3):454. Hozawa, S. and M. Toriumi. 1941. Some fresh-water Bryozoa found in Manchoukuo. Sci. Rep. Tohoku Imp.‘Univ. l6(4):233-241. Hurrell, H. 1927. Ecology of fresh-water Polyzoa in.East Anglia. Jour. Roy. Microsc. Soc. 47(3):135-142. Hyatt, A. 1868. X. Observations on Polyzoa. Suborder Phylac- tolaemata. Comm. Essex Inst. 5:193-232. Hyman, L. H. 1958. The occurrence of chitin on the lophophorate phyla. 8101. 3111. 11.431.06-112. . 1959. The invertebrates: smaller coelomate groups. 783 p. New Yoflk: M0 Grew-Hill Co. Jackson, F. S. 1919. The preservation of fresh-water Bryozoa. Trans. Amer. Micr. Soc. 38:217-220. Jewell, M. E. 1935. An ecological study of the fresh-water sponges of northern Wisconsin. Ecol. Monographs 5:461-504. Judd, W. I. 1950. Pectinatella ma ifica Leidy (Bryozoa) in the Dundas Wt—flon, Giff-Canadian Field Nat. 64(6):191-192. Jullien, J. 1885. Monographie des Bryozaires d'eau douce. Bull. Soc. 2001. de France 10:91-207. Kellicott, D. S. 1882. Polyzoa. Observations on species detected near Buffalo, N. Y. Proc. Amer. Soc. Microscopists 4:217-229. Kenk, R. 1949. The animal life of temporary and permanent ponds in southern Michigan. Misc. Pub1., "be. 2001., Univ. of Mich. No. 71:71p. Kraepelin, ‘K. 1887. Die deutschen Susswasserbryozoen. I. Anatomisch Systematischer Teil. Abhandl. Gebiete Natu- wiss, verein Hamburg 10:1-168. . 1906. Eine Susswasserbryozoe (Plumatella) aus Java. Mittheil. Nat. Hist. Mus. Hamburg 23:1333146. Lacourt, A. 1948. On two fresh-water Bryozoa (Phylactolaemata) from Belgian Congo. Revue Zool. Bot. Africaine 40:229-234. . 1951. Bryozoa of the Netherlands. Archives Neerlandaises 2001. 8:289-321. ~301- Lampert, K. 1899. Bryozoaires Das Leben der Binnengewasser. Leipzig:40-61 Lee, L. 1936. Notes on some fresh-water Polyzoa of Peiping. Sinensia 7:399-407. Leidy, J. 1851a. On Plumatella diffusa n. sp. Proc. Acad. Nat. Sci. 5:261-2627 . 1851b. Cristatella magnifies n. 3. Proc. Acad. Nat. Sci. Phila. 5:265-266. . 1851c. On some American fresh-water Polyzoa. Proc Acad. Nat. Sci. Phila. 52320-322. . L0ppens, K. 1908. Les Bryozoaires d'eau douce. Ann. Biol. Lacustre 3:141-183. Mhrcus, E. 1925. Tentaculata. Kransfuhler: Bryozoa. Moostiere. Biologie der Tiere Deutschlands. Lieferung l4, Teil 47: 46 p. . 1926. Beobachtungen und Versuche an lebenden Susswasser bryozoen. Zool. Jahrb. Abt. Syst. Okol. Geogr. Tiere 52 2279-350 0 . 1934. Uber Lo ho us crystallinug (Pall.) Zool. Jahrb. Abt. Anat. 58?5513§6€. . 1941. sabre Bryozoa do Brasil. Univ. Sao Paulo, Brazil no 0 5 33-208 0 . 1942. Sobre Bryozoa do Brasil II. 2001. Univ. Sao Paulo, Brazil. no. 6:57-106. Marcus, Eveline. 1946. New Brazilian form of Fredericella sultana. Communicaciones Zool. Mus. Hist. Natur. HontevIdeo 2. no. 31:1-10. . 1953. Bryozoa from Lake Titicaca. Zoologia, Univ. Sao Paulo, Brazil. (18):149-163. ”an, E0, E0 Go Lmsley' and Re Lo Usinger. 1953. MOthOdS and principles of systematic Zoology. 336 p. New York: Mb Graw-Hill and Co. Oka, A. 1908. Uber eine neue Gattung von Susswasserbryozoen (Stephanella n. g.) Annotationes Zoologicae Japonenses 68277- 850 Otto, F. 1921. Studien uber das Regulationsvermogen einiger Susswasserbryozoen. Arch. Entw.-Mech. 47:399-442. -302- Paterr, P. 1924. Mitteilungen uber die Susswasser-Bryozoen Bulgarians. Trav. Soc. Bu1g. Sci. Nat. 11:119-121. Potts, E. 1884. On Paludicella erecta. Proc. Acad. Nat. Sci. Phila. 36:21 - ' 'Roelors, E. 1941. Fisheries survey of Burke, Park, and Rose Lakes in Clinton County, and Lake Lansing in Ingham County. Inst. Fish. Res. Rep. no. 68931-27. Prenant, M. and.G. Bobin. 1956. Bryozoaires I. Entoproctes, Phylactolemes. Ctenostomes. Fauna de France 60. . 398 p.3Lechevalier. Prescott, G. I. 1951. Algae of the western Great Lakes area. Cranbrook Inst. Sci. Bull. 3031-946. ' Richardson, R. E. 1928. The bottom fauna of the Niddle Illinois R1V01‘, 1913-19250 Bu11e Illa Nat. Hist. 81.11.70 173387-475. Rogick, M. D. 1934. Studies on fresh-water Bryozoa. I. The occurrence of Lophogpdella carteri (Hyatt) 1866 in North America. Trans. Amer. Micro. Soc. 53:416-424. . 1935a. Studies on freshpwater Bryozoa. II. Bryozoa or e Erie. Trans. Amer. Mior;,Soc. 54:245-263. . 1935b. Studies on fresh-water'Bryozoa. III. The development of Lo ho odella carteri var. tygica. Ohio Jour. Sci. 35(6’:§57- 367. , . 1936. Studies on freshpwater Bryozoa. IV. 0n the variations of statoblasts of Lo hopodella carteri. Trans. Amer..Micr. Soc. 55:32 - . 1957. Studies on fresh-water Bryozoa. v. Some additions to Canadian fauna. Ohio Jour. Sci. 37399-104. . 1938. Studies on fresh-water Bryozoa. VII. On the viability of dried statoblasts 0: Lo ho odella carteri var. tygica. Trans. Amer. Micr. Soc. 575253178- . . 1940. Studies on freshpwater Bryozoa. Ix. Additions to New York Bryozoa. Trans. Amer. Micr. Soc. 59:187-204. . 1941. Studies on fresh-water Bryozoa. x. Occurrence of Plumatella casmiana in N. A. Trans. Amer. Micr. Soc. 60:211- 220. _ . 1943. Studies on fresh-rater Bryozoa. XIV. The occur- rences of Stolella indica in North America. Annals N. Y. Acad. Sci. 45316331 . -305— . 1945a. Studies on freshewater Bryozoa. XV. Hyalinella punctata growth data. Ohio Jour. Sci. 45:55-7 . . 1945b. Studies on freshswater Bryozoa. XVI. Frederi- cella australiensis var. browni, n. var. Biol. 5511. WIS-223 e Rogick, M. D. and J. D. Brown. 1942. Studies on freshpwater Bryozoa. XII. A collection from various sources. Ann. “9' York Acado 8010 433123-144. Rogick, M. D. and H. Van der Schalie. 1950. Studies on fresh- water Bryozoa. XVII. Michigan Bryozoa. Ohio Jour. Sci. 50 2 136‘146 e Rusche, E. 1938. HydrObiologische‘Untersuchungen an niedarr- heinischen Gewassern. X. Nahrungsaurnahme und Nahrung- sauswertung bei Plumatella fungosa (Pa11.). Arch. Hydrobiol. Stuttgart. 33:2 - . Schlichting, H. E. 1958. The role of waterfowl in the dispersal of Algae. Ph.D. thesis. Mich. State Univ.:259 p. Sokolowski, J. 1960. The Monte .Swan in Poland. State Council Conserv. Nat. Poland, warsaw.‘Krakow. NR 131-28. Takahasi, S. 1934. Sur Lo ho odella carteri (Hyatt), Bryozoaire d'eau deuce, origInaIre at Tormese. Annot. Zool. Japonenses 14:347-350. Tanner, V. M. 1932. Ecological and distributional notes on the fresh-water sponges and Bryozoa of Ut‘hm Utah.Acad. Sci. 92113-115. ' Toriumi, M. 1942. Studies on freshpwater Bryozoa of Japan. III. Freshpwater Bryozoa of Hokkaido. Sci. Rep. Tohoku ‘Univ. 17(4):l97-205. . 1943. Studies on freshrwater Bryozoa of Japan V. The variations occurring in the statoblasts and in the number or the tentacles of Cristatella mucedo Cuvier. Sci. Rep. TohOku Univ. l7(4):2 - . ”""“‘ . 1951. Taxonomical study on freshpwater Bryozoa I. Fredericella sultana (Blumenbach). Sci. Rep. Tohdku n v. :1 - . . 1952a. Taxonomical study on freshrwater Bryozoa II. Paludicella articulata (Ehrenberg). Sci. Rep. Tohoku Univ. 19(1): " e . 1952b. Taxonomical study on freshewater Bryozoa III. Plumatella osburni (Rogick & Brown). Sci. Rep. Tohoku Univ. 19(4)?2€U:§33. -304- . 1952c. Taxonomical study on fresh-water Bryozoa IV. On Plumatella gavanica.Kraepelin reported by Vorstman in 1928. Sci. ep. 0 oku Univ. 19(4):264-269. . 1952d. Taxonomical study on fresh-water Bryozoa V. On.a geminate form.named Plumatella Jugalis by Allman. Sci. Rep. Tohdku Univ. 19(4): 315- 319. . 1952e. Taxonomical study on fresh-water Bryozoa VI. Plumatella emar inata Allman. Sci. Rep. Tohoku‘Univ. -33Z‘JE"“' . . 1954a. Taxonomical study on fresh-water Bryozoa VII. Additions to the reconsideration on the ectocyst of Plumatella §§arginata Allman. Sci. Rep. Tohbku‘Univ. 3 ‘2 e . 1954b. Taxonomical study on fresh-water Bryozoa VIII. Plumatella fruticosa Allman. Sci. Rep. Tohdku‘Univ. 20(4):293- 3 52. . 1955a. Taxonomical study on fresh-water Bryozoa IX. Plumatella repens (L.). Sci. Rep. Tohdku‘Univ. 21(4):51-67. . 1955b. Taxonomical study on fresh-water Bryozoa XI. Stephanella hina Oka. Sci. Rep. Tohoku'Univ. 21(4):l31-136. . 1955c. Taxonomical study on fresh-water Bryozoa XII. On Plumatella re ns var. minuta Toriumi, 1941. Sci. Rep. u n v. (4):13W - . 1955d. Taxonomical study on fresh-water Bryozoa XIII. H¥%1inella Egnctata (Hancock). Sci. Rep. Tohoku Univ. . 1955s. Taxonomical study on fresh-water Bryozoa XIV. econsideration on H linella toanensis Hozawa and Toriumi. Sci. Rep. ToEdEE UnIv. 21(3):249-255. . 1956a. Taxonomical study on fresh-water Bryozoa XVI. Lophopodella carteri (Hyatt). Sci. Rep. Tohdku'Univ. . 1956b. Taxonomical study on fresh-water Bryozoa XVII. General consideration: Interspecific relation of des- cribed species and phylogenic consideration. Sci. Rep. Tohdku Univ. 22(4):57-88. Vangel, E. 1894. Daten zur Bryozoen-fauna Ungarns. Zool. Ans. 17 3 153-155 0 Vorstman, A. G. 1928a. Some fresh-water Bryozoa of West Java. Treubia 10:1-14. -305- . 1928b. Fresh-water Bryozoa from East Java. Treubia 10:163-165. Ward, H. B. 1896. A biological examination of Lake Michigan. in the Traverse Bay region. Bull Michigan Fish.Comm. no.6:100pp. Ward, R. B. and G. C. Whipple (Edmondson, W. T. Revision) 1959. Fresh-water Biology. 1248 p. New YorkaJohn Wiley and Sons, Inc. ' Wesenberg-Dund, C. 1896. Biologiske Studies over Ferskvands- bryozoan. Resume en francais. Vidensk. Meddel. Dansk. Naturhistor, Foren 8(5):252-363. . 1907. On the occurrence of Fredericella sultana Blumenbach and Paludicella.Ehrenbergi. _Meddei. om Gronland 34:61-75. Wiebach, F. 1952. Uber den Ausstoss von Flottoblasten bei Plumatella fruticosa (Allamn) Zool. Anz. 149:181-185. Iéipzig. . 1953. Uber den Ausstoss von Flottoblasten bei Pluma- tellen. Zool. Anz. 15l:266-272.. . 1954a. Uber Plumatella fruticosa. Arch. Hydrobiol. 49 3258-272 0 . 1954b. Proliferationsknospung bei Susswasserbryozoen. Mikrdkosmos 42:232-234. Zschokke, F. 1906. Ubersicht uber die Tiefenfauna des Vierwald- stattersees. Arch. Hydrobiol. 2:1-8. by R:- "' x19’:t 1‘1. ‘ ‘{ ' bl: g' . ' EA : ‘ and.“ “35; Ufi‘.‘ r RENEE} USE WU