TAXONOMIC AND STRATIGRAPHEB smm—mmce OF DINOFLAGELLATES AND ACRETARC?-!S OF THE NAVARRO GRDUP (MAESTRMRTIAN) FROM EAST CENTRAL AND SUUTHWEST TEXAS Thesis for the Begree cf Ph. D. MICHIGAN STATE UNlVERSlTY JAMES B; ZAITEFF 19.6,? tn.- This is to certify that the thesis entitled Taxonomic and Stratigraphic Significance of Dinoflagellates and Acritarchs of the Navarro Group (Maestrichtian) from East Central and Southwest Texas presented by James B. Zaitzeff has been accepted towards fulfillment of the requirements for _P_hD___degree inc—3010.52 ALI. QM Major professor Datei/tPI/é 7 0-169 . I # LIBRARY I J 1 I 1 1'- 5?}; t 5' E35“, .. .'.I liter!!! :L .} .Af;...li! in... [FrillfilrL g.-. :1- I t. i t t . .. . _ , f: A? . u‘ . . .t . ..’y\.r (II (I) r9' “‘1 ‘u ABSTRACT TAXONOMIC AND STRATIGRAPHIC SIGNIFICANCE OF DINOFLAGELLATES AND ACRITARCHS OF THE NAVARRO GROUP (MAESTRICHTIAN) FROM EASTCENTRAL AND SOUTHWEST TEXAS by James B. Zaitzeff Analysis of dinoflagellates and acritarchs from a composite surface section near Austin, Texas, and a subsur— face cored section in Frio County, Texas, has revealed an abundant and varied microplankton assemblage. Eighty-one species distributed among 35 genera are recorded. Four genera and thirty-nine species are described as new. The vertical distribution of these species permits a zonation of the Navarro rocks in the Austin area. The widespread geo— graphic occurrence of several Species and their high rela- tive abundance in samples from the two sections studied per— mits the use of some species for correlation of the two sec- tions. It is concluded that pollen-spore/microplankton ratios in the Austin composite section are useful for deter- mining relative water depths or possibly distance from shore. The former interpretation is supported by the foraminiferal composition. James B. Zaitzeff Comparative observations of microplankton assem- blages from other areas indicate that the Corsicana and Kemp Formations in the Austin area and the Escondido and Olmos Formations in Frio County have assemblages that closely resemble that of the Red Bank Formation (Maestrichtian) of New Jersey, whereas the Neylandville Formation assemblage contains many species which have been described elsewhere from older rocks. TAXONOMIC AND STRATIGRAPHIC SIGNIFICANCE OF DINOFLAGELLATES AND ACRITARCHS OF THE NAVARRO GROUP (MAESTRICHTIAN) FROM EASTCENTRAL AND SOUTHWEST TEXAS BY James B. Zaitzeff A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Geology 1967 O 4 “U :77/1/(0 12"“)‘0 (p7 ACKNOWLEDGMENTS The writer expresses his sincere thanks and apprecia— tion to Dr. Aureal T. Cross of the Department of Geology and the Department of Botany and Plant Pathology, Michigan State University, under whose guidance this study was made, for his assistance and constructive criticism and for his valu- able suggestions in the taxonomic treatment of this work. The writer is also deeply indebted to Dr. C. E. Prouty, Dr. J. E. Smith, Dr. B. T. Sandefur of the Department of Geology, Michigan State University and to Dr. G. E. Prescott, Department of Botany and Plant Pathology, Michigan State University, for their suggestions during the study, and critical reading of the manuscript. Sincere appreciation and thanks are also extended to Dr. W. R. Evitt of the Department of Geology, Stanford. University and to Dr. Graham Williams of the Pan American Petroleum Corporation, Research Center, Tulsa, Oklahoma, for their examination of many of the slides and illustrations used in this study and suggestions concerning some aspects of the morphology and taxonomy of a number of the dinoflag- ellate species. The writer also eXpresses thanks here to Shell Oil Company for assistance given in providing sample locality data for the Austin, Texas composite section, and also to the Humble Oil and Refining Company for providing the sub- surface cored section of the Navarro group from Frio Count Texas. Recognition and appreciation is extended to the Society of the Sigma Xi for a Grant-In-Aid and to the Office of the Dean of the College of Natural Science, Michigan State University, for a grant matching the Sigma Xi Award, for support of field and laboratory work during the course of the study. ***** ii 0‘— -¢ .05 INTRODUCTION . . . . TABLE OF CONTENTS Purpose and Scope . . . . . . . Previous Work . . . . . . . . . Part I. GEOLOGY . . . Nomenclature and Stratigraphic Relations General Features of the Navarro Group . II. DINOFLAGELLATE AND ACRITARCH CONSIDERATIONS Modern Dinoflagellate Morphology Fossil Dinoflagellate Morphology Classification of Dinoflagellates Classification of Acritarchs Paleoecology and Ecology of Dinoflagel- lates . . III. METHODS . . . Sample Preparation Techniques . Sample Analysis . . . . . . . . IV. SYSTEMATIC DESCRIPTIONS . . . . .‘ Group Acritarcha . . . . . . . Class Chlorophyceae . . . . . . Class Dinophyceae . . . . . . Family Family Family Family Family Family Family Family Family Hystrichosphaeridiaceae Hystrichosphaeraceae Areoligeraceae . . . Hystrichodiniaceae . Gymnodiniaceae . . . Gonyaulacaceae . . . Pseudoceratiaceae . Deflandreaceae . . . Apteodiniaceae . . . Dinoflagellates of Uncertain Affinity iii 11 ll 13 17 18 22 22 23 24 24 32 34 36 68 78 79 88 92 103 105 Part Page V. STRATIGRAPHIC AND PALEONTOLOGIC CONSIDERATIONS . . . . . . . . . . . . . . . 110 List of Species in the Austin Composite Section . . . . . . . . . . . . . . . . . . 110 List of Species in the Frio Section . . . . . 113 Zonation and Correlations . . . . . . . . . . 115 Zonation of the Austin Section . . . . . 115 Correlation of the Navarro Group, Austin and Frio Sections . . . . . . . 118 Dinoflagellate - Acritarch Comparisons with Other Areas . . . . . . . . . . . . . . . . 129 Paleoecologic Interpretations . . . . . . . . 132 VI. PALEONTOLOGIC AND STRATIGRAPHIC CONCLUSIONS . . 137 REFERENCES . . . . . . . . . . . . . . . . . . . . . . 139 APPENDICES . . . . . . . . . . . . . . . . . . . . . . 151 PLATES . . . . . . . . . . . . . . . . . . . . . . . . 165 iv Figure 1. LIST OF FIGURES Generalized section showing the position of the Navarro Group in the Upper Cretaceous (Gulf Series) in eastcentral Texas . . . . . Composite section of Upper Cretaceous and Paleocene rocks in the vicinity of Austin, Texas 0 O O I O O O O I C O O O O O O O O O 0 Map showing the belt of outcrop of the Navarro Group in Texas, and section localities O O O O O O O O O O O O O O O O 0 Vertical distribution of dinoflagellates and acritarch species occurring in the Austin composite section . . . . . . . . . . . . . . Vertical distribution of dinoflagellate and acritarch species' occurring in the Frio A'County subsurface section . . . . . . . . . . 10. 11. 12. 13. Relative abundance of Cyclonephelium sp. 1 in the Austin and Frio Sections . . . . . . . Relative abundance of Forma A Sp. 1 in the Austin and Frio sections . . . . . . . . . . Relative abundance of Forma B sp. 1 in the Austin and Frio sections . . . . . . . . . . Relative abundance of Deflandrea magnifica in the Austin and Frio sections . . . . . . . Relative abundance of Svalbardella lidiae in the Austin and Frio sections . . . . . . . Relative abundance of Hystrichosphaera ramosa var. 1 var. nov..in the Austin and Frio Sections 0 O O O O O I O O O O O O O O O Correlative horizons of the Austin and Frio sections . . . . . . . . . . . . . . . . Pollen and spore microplankton ratio in " the Austin section. . . . . . . . . . . . . . V Page 116 120 121 122 124 125 126 127 128 134 LIST OF APPENDICES Appendix Page A. Glossary of Dinoflagellate Terminology . . . 152 B. Sample Localities . . . . . . . . . . . . . . 164 vi Y; ”t ahv R\V INTRODUCTION Purpose and Scope Numerous rock samples from the Navarro group have been shown to contain abundant acid insoluble entities, i.e., paleomicroplankton, pollen and spores. The purpose of this study is to report on the occurrences of dinoflagellates and acritarchs from selected outcrop sections, and cores of sub- surface rocks of the Navarro group of eastcentral and south- west Texas, and to demonstrate that vertical successions of distinctive dinoflagellate and acritarch assemblages can be of aid in the biostratigraphic zonation and correlation of rocks comprising the Navarro group in this area. Two essentially complete sections of the Navarro group were analyzed. The first, a composite section of Navarro rocks, is in the vicinity of Austin, Texas, and is based on several outcrop localities and supplemented by sec— tions from two cores. The total thickness of this composite section is approximately 550 feet. The second section anaé lyzed is a subsurface cored sequence consisting of Escondido and Olmos rocks from the northwest part of Frio County, Texas. The section is approximately 1100 feet. The two sections are 160 miles apart. U-.- . or... .IJ: - A l ‘ I L): [1‘ I!) A \‘fl 1‘ Previous Work There are relatively few published works describing dinoflagellates from Upper Cretaceous and Tertiary rocks from North America. There are no major Maestrichtian assem- blages from North America described in the literature to date, except Drugg's very recent report (Drugg, 1967) of the Upper Moreno Formation of California, which appeared after the present study had been completed. One must rely primar- ily on European and Australian works for assemblage compari- sons. Tasch (1964) described an Albian assemblage from Kansas, though his taxonomic treatment is inadequate and not used here. Other North American works which include some descriptions and illustrations of dinoflagellate assemblages are: Singh (1964) and Leopold (1964) though both of these describe materials from Cretaceous rocks of older age than Maestrichtian, and Stanley (1964) which describes forms from the Paleocene of South Dakota, of which many species appear to be conspecific with Navarro forms. European and Australian Mesozoic dinoflagellate Studies are more extensive. Davey and others (1966); Downie (1957); Neale and Sarjeant (1962); Cookson and Hughes (1964); Deflandre (1937, 1938, 1947, 1952); Klement (1960); Eisenack (1959); and Wetzel (1933, 1961) have contributed signifi- cantly to the knowledge of Mesozoic dinoflagellates. I. GEOLOGY Nomenclature and Stratigraphic Relations The Navarro Group, formerly classed as a Formation, includes the youngest Cretaceous rocks in the Gulf Coast, the upper part of the Gulfian Series, (Figs. 1, 2). The existence of Upper Cretaceous rocks in Texas was first rec- ognized by Shumard (1863) to which he applied the name "Navarro beds." His type section was located somewhere in Navarro County, and may have been a composite of several sections, but he did not specify the locations of the type locality through Chatfield Point and Corsicana are frequently mentioned as fossil localities in his text, and one or both may be portions of the type locality. Synonyms of the Navarro in the literature are: Glauconitic Division or Greensand Division, Ripley Group, Exogyra costata Assemblage Zone clays, Webberville Formation and the Pulliam Formation. The Navarro Group has been subdivided into four for- mations in Navarro, Kaufman, and Hunt Counties, where it is most completely developed. These formations are in ascend- ing order; Neylandville marl, Nacatoch sand, Corsicana marl, and Kemp clay. This classification was adopted for use by the United States Geological Survey and appears on the geo- logical map of Texas issued by the United States Geological Survey in 1937. In] 3 EAST- CENTRAL é TEXAS 5 3,, WILLS POINT _. m u >' a. g g a ‘3‘ 3 FORMATION ”I.“ m In a v—fi v‘w‘v v‘w — z m - °= KINCAID E5 3 :° EMATION 0. § § KEMP CLAY .— 0 g, 0 Wm .33, :3 g NACATOCH SAND 3 g 3: NEYLANDVILLE ’ w z MARL — - C v V v ‘— w ———v 5' _, (UPPER PART) 5?, n: 4 -— — ———————— A E S = _. .I’ as"... 2..---. E 3 a: WOLFE CITY 4 o 3 .. 9!? £93158. .. - m < >_ 2 l- q 3 g *' (LOWER PART) _'_I a: ~* ~— ‘v‘v‘v‘ v E: g: 'g—i % AUSTIN CHALK 5 5 8 .. LP... ,_. - 11"; 1: 1 i g EAGLE FORD SHALE we 1.». .1 we 3 2 g: woooaINE SAND Ill 0 FIG.I. GENERALIZED SECTION SHOWING THE POSITION OF THE NAVARRO GROUP IN THE UPPER CRETACEOUS (GULF) SERIES, IN EAST-CENTRAL TEXAS. (AFTER STEPHENSON, l94|I COMPOSITE SECTION OF UPPER CRETACEOUS AND PALEOCENE ROCKS IN THE VICINITY OF AUSTIN, TEXAS I.I.l z 8 w ,_ a 8 ‘3‘ D KINCAID FEET E E o ‘ -IOO % I- 200 o 95 ~3OO o E -4OO E 8 NEYLANDVILLE- -500 8 NACATOCH 3 ‘3 500 m a: In ° b7OO .J UPPER MARL E 5 Ir L800 3 < E o 2 -900 § QZAN a PECAN CAP CI_I_ALI<§ >- I— :1. LOWER MARL moo -I200 BUROITT MARL FIG.Z. SHOWS COMPOSITE SECTION OF UPPER CRETACEOUS AND PALEOCENE ROCKS IN THE VICINITY OF AUSTIN, TEXAS. (AFTER,PETE ROSE, SHELL OIL COMPANY UN- PUBLISHED REPORT I Southwest of Navarro County, and westward, the Kemp Formation changes, along its strike, into rocks of different lithology, to which the name Escondido Formation is given. The lithologic change is gradational from the Kemp and the separation of these two formations is rather arbitrary. Invertebrate fossils near the base of the Navarro Group in Bexar and Medina Counties and near the base of the Escondido Formation farther west in Medina County indicate that the age of basal beds there is approximately equivalent to the middle of the Navarro in Navarro, Hunt and Kaufman Counties in northeastern Texas. This indicates the exis- tence of an unconformity at the base of both the Navarro Group and Escondido Formation in the Bexar-Medina Counties area. This unconformity between the Navarro and underlying Taylor marl continues westward between the Anacacho lime- stone and the overlying Escondido Formation, but in Maverick County (Rio Grande Embayment area) the stratigraphic gap represented by the unconformity is in part filled—in by the non—marine beds, originally known as the "coal series," but now defined as the Olmos Formation. In Maverick County, the Olmos is overlain by the Escondido. The Olmos overlies the San Miguel (Senonian) which may be at least in part equiva- lent to the Anacacho limestone farther east. The Navarro Group of central and northeastern Texas and the Escondido Formation of the southwestern part of the state are unconformably overlain by various overlapping Tertiary Formations of Midway or Wilcox age. The amount of time represented by the hiatus between the uppermost Navarro or Escondido and the overlying Tertiary is unknown but it is probably a long interval. It has been stated by Stephenson (1927) and others, that at different places on the outcrop, Navarro of differ— ent ages appears beneath the overlapping Tertiary strata. Stephenson (1927) points out that the upper part of the Escondido Formation is probably younger than the uppermost beds of the Navarro Group in central and northeastern Texas, but that these younger rocks were formed well within the limits of the Mesozoic Era. At the present time the zona- tion of the Navarro in the surface and subsurface is insuf- ficiently supported in the literature to give a clear answer to the question. The difference of age of the surface depoSits of the Navarro at different localities, may be in part due to differing amounts of material being removed from the top of the Cretaceous at various places, some now exposed in the outcrop, or that perhaps the sea retreated earlier in some areas than in others. The Exogyra costata zone, a major faunal zone of Upper Cretaceous age, extending from New Jersey to the Rio Grande and beyond into Mexico, is co-extensive with the strata of the Navarro group and its equivalent strata. The species Exogyra cancellata Stephenson, is restricted to the lower part of the Exogyra costata Zone and forms a much thinner zone having the same areal extent as the Exogyra costata Zone. In Texas, the Neylandville marl is co-exten- sive with the Exogyra cancellata Zone. General Features of the Navarro Group The Navarro Group is exposed at the surface in a belt up to 23 miles in width, extending from Red River Valley, in Bowie County, where it attains its greatest width (Fig. 3). The marls, clays, and sands comprising the Navarro Group weather to gray and black soils and subsoils that blanket and partly conceal the formations, or alter their appearance, except where there are fresh exposures. The exposures of greatest thickness occur along banks and bluffs of streams, and occasionally good outcrops are also found in gullies, road and railroad cuts, and along ditches and near water tanks. Because of the covering by weathered materials, differentitation and mapping of the various formations and accurate stratigraphic placement of outcrop samples often becomes difficult and sometimes impossible. The four forma- tions of the group have been differentiated and mapped, though in a highly generalized fashion, for the most part. The sediments comprising the marine rocks of the Navarro Group were deposited in waters probably not exceed- ing 100 fathoms (Stephenson, 1942) but for the most part, deep enough to escape appreciable disturbance by wave action. IOO" \ 98° 95° 9‘4" ”I + "V’k , 0 x + L I + 34° V1 "*\. KT" I \‘T-I A R K A-\$‘\\\\\\‘ ‘ l /13}“‘. F‘J-sf“ \ I ' A ' I I ,1 I, J I/‘si "' 7‘ 61-..... I DALLAS ‘ ‘H l r" §~ -'———-~A, LL A 32° P>t"3 ‘ ' -32° C \ 1‘ / \ A S 3 5 30° + *1, ‘3°° ti / + -28' 23° + 0? v? ' \I G . ‘ O 59 _I‘oo MILES 0 CORE LOCATIONS Q OUTCROP LOCATIONS + 1 I00’ 98° 96" 26' - 26° 1 94° FIG 3 MAP SHOWING THE BELT OF OUTCROP OF THE NAVARRO GROUP IN TEXAS. AND SECTION LOCATION. 10 The rocks consist dominantly Of massive bedded marls, chalky marls, clays, and sands with subordinate indurated concre- tionary masses or layers cemented with calcareous carbonate. Bentonite forms a minor though well distributed, part of the group. The aggregate thickness of the Navarro sediments now exposed anywhere in the outcrop is estimated to be 550 to 750 feet or more, but down-dip in the subsurface the group thickens appreciably, to over 1000 feet. In Maverick County, the Escondido Formations, equiv- alent to the Kemp clay in age, attains thicknesses in out- crop of 550 to 750 feet. The Escondido here consists of dark clays and marls, interbedded with limestones, shales and sandstones of quite variable thickness and areal distri- bution. In the area of outcrop of the Olmos Formation in Maverick County, it ranges in thickness from a few feet to 400 or 500 feet. The formation consists largely of non— marine clays, shales and sandstones, and seams of coal. Along Olmos Creek, in Maverick County, rocks of irregularly stratified sandstones and clays containing ferruginous con- cretions and silicified wood are exposed. The small beds of sand and clay usually are not constant laterally, but are interfingering lenses. V“: ... it s -Q. n... A: "v‘. I bnA .— u... “zy- v“ ‘1' f) n '9- u.‘ (U o h «A; V. II. DINOFLAGELLATE AND ACRITARCH CONSIDERATIONS Modern Dinoflagellate Morphology The dinoflagellates are flagellated Protista, char- acterized by having two flagella. One flagellum is rather elongate, usually extending posteriorly with reference to the direction of motion. The second emerges from the same part as the first, i.e., on the ventral surface, and lies in a circumferential transverse groove, called the girdle, in which it moves in an undulating fashion. The girdle is usually, but not always, more or less spiral, so that its left end is more posterior than the right end when the orga— nism is seen from the ventral side. In a number of forms, however, there is no displacement of the girdle, so that the two ends are opposite, though separated, from each other. The longitudinal flagellum is in a somewhat less well- defined and usually broader longitudinal furrow, the sulcus. Both girdle and sulcus are almost always provided with dis— tinct lips. The girdle and sulcus are distinctly morpho- logic features of the dinoflagellates, thus making the group on the whole very easy to recognize. Many species of the dinoflagellates possess only a protective flexible pellicle, but others have a well-defined porous theca, composed of 11 12 cellulose. In the modern genus, Prorocentrum, the theca is simple, whereas in Ceratium, and.most other modern thecate genera, it is composed of numerous sculptured plates, whose arrangement and sculpture are of considerable importance in the differentiation of species. Reproduction is largely asexual, by means of binary fission, and this may in some species result in temporary chains of individuals. The division is simple longitudinal or oblique. When individuals divide, the two halves regen- erate new halves. Conjugation similar to that occurring in some of the green algae has been observed in Ceratium and other types of sexual reproduction have also been described. Another method of multiplication, in some cases, is the for- mation of a cyst, within which, the protoplast of the orga- nism is concentrated. Such a cyst may subsequently divide to form two or more individuals. Some genera as Ceratium are capable of producing resting spores which allow survival during adverse conditions. Usually during binary fission in the unarmoured dinoflaggelates, a typical cyst is formed, for apparently the organisms require protection and rest during this critical period. The cyst is usually very delicate, so that the protoplast easily emerges from it, though in some forms the cyst is tough and resistant. Various dinoflagellates possess holOphytic, sapro- phytic, holozoic, and.mixed nutritions, and in some instances different types of nutrition are known to occur even among 13 different species of the same genus. In the genus EXEEQ? dinium, for example, G, brevis is strictly holOphytic, and g, incisum is holozoic, but g, fulgens has been observed to contain both chromatophores and food vacuoles, showing that it has mixed nutritions. A number of species, including .g. aureum, appear to be saprophytic. Fossil Dinoflagellate Morphology The current classification of living dinoflagellate species is based principally on their tabulation (plate arrangement) and the character of the motile cell. Descrip- tive morphologic terms used for modern dinoflagellates have been used in the descriptions of those fossils thought to be dinoflagellates. There has been much discussion Of the alternate concepts that fossil dinoflagellates are, in most instances, dinoflagellate cysts, or that they are in fact, the motile theca, i.e., the whole body, of dinoflagellates. Some workers consider that fossil dinoflagellates are not the remains of the motile theca and that all fossil dino- flagellates recognized to date are dinoflagellate cysts. Evitt (1965) was strongly in favor of this concept, but later (in press), has come to the conclusion that there is not yet sufficient evidence, at least in some cases, e.g., fossil Gymnodinium, to warrant a conclusive decision at this time. Many species of some genera from the Upper Cretaceous rocks, particularly Peridinium and Gymnodinium, which lack 'V" .0- .v: ‘0 I” (II he. RA: 7-. g 4 i '1 14 true archeopyles and show none of the other characteristics of cysts, have been considered to be the motile theca of the organisms. Some species of fossil Gymnodinium studied by Evitt (in press) and some specimens of g, nelsonense and g. sp. 2, which I have studied, are shown to possess a partic- ular opening at the apex of the epitheca (epitract), which can be considered to be analagous to an archeopyle. Although, as Evitt has stated (in press), the presence of wall canals in Specimens of fossil Gymnodinium (which may imply open communication between the contents of the cyst and the sur- rounding water) seems inconsistant with the interpretation of a cyst. Although little is known of the encystment of modern dinoflagellates, there is considerable evidence accumulating that at least most of the fossils recognized as dinoflagel- lates are morphologically cysts rather than motile thecae. If we are then truly dealing with fossil dinoflagellate cysts rather than the preserved motile theca, the use of morphologic terms applied to the modern dinoflagellate theca would therefore not be appropriate. New structures may be characteristic of some cysts which have no cOunterpart in the motile cell. Therefore the continued use of thecal terms to describe cysts would lead to confusion. Davey and others (1966) have suggested several morphologic terms for cysts which, at the present time seem appropriate, and are here used (see Appendix A). 15 Perhaps a reasonable direction of study in determin- ing critical morphologic features of cysts would have to come through studies of cultures and the examination of cysts and their associated theca from the modern seas and recent bottom sediments. Evitt (1964) has shown that dif- ferent extant species of Gonyaulax produce morphologically different cysts, and these, in no sense, resemble the orig— inal thecae in which they were enclosed. In some forms, both recent and fossil, the resting cyst will take on the aspect of its theca. It is difficult to asSign a modern dinoflagellate cyst to a species or genus, which is founded on the living motile stage, let alone to be able to make such an assignment to a fossil cyst. There are a number of reasons for postulating that it is usually the cyst and not the motile theca of dinoflag— ellates which is observed in the fossil state. These are stated below: 1. There is in Some fossil dinoflagellate species the possibility of a "non-functional" girdle, which is inca— pable of containing a flagellum because of high membranes or ridges which divide the girdle into polygonal fields. Hystrichosphaera furcata, Gonyaulax jurassica and Wetzeliella sp. are thought to possess such a "non-functional" girdle. In many species of Gonyaulax the field boundaries, including those that cross the girdle, are provided with membranes that rise perpendicularly from the cyst. 16 2. External appendages or processes of many dino- flagellate tests, such as Hysterichosphaera and Hystrichos— pphaeridium, are probably more logically interpreted as sup- porting features which develOped between the wall of the motile theca and the wall of the cyst. External processes are less commonly observed on the motile theca. 3. An archeopyle, a more or less uniformly shaped, precisely located and oriented opening on the test of some fossils, which corresponds to a specific location in the structure of modern tabulate dinoflagellates, is character- istic of some fossil dinoflagellates. It is formed by the loss of either a single plate or group of plates (plate field), which allows the release or extrusion of the cell contents. An orifice of this type, which produces the archeopyle in the cysts of fossil or modern dinoflagellates, is unknown in the theca of modern forms. The cell contents, in living forms, escapes from the motile theca, by the open- ing of the theca along some of the many sutures between thecal plates. 4. Evitt (1966) stated that the modern dinoflag- ellate theca, which is composed of cellulose, is destroyed on boiling in acetolysis mixture, and a milder treatment in heated sodium hypochlorite reduces the plates to an unrec- ognizable mass, whereas the modern cyst withstands these treatments. It is possible that the thecae of living F‘ d- .5- '0: -v .0- 0‘ ' ‘ v.. .i ‘I ‘1 n: 4 "a C I In l7 dinoflagellates, upon death or encystment, were destroyed by natural processes of decay and degradation. 5. There is a distinct flagellar pore present in the sulcal region of the ventral surface of the motile theca in modern forms. In fossil forms, these are not observed. 6. In the fossil state, in most dinoflagellates, there is a two-layered wall. Most modern forms do not appear to possess a double wall. Several extant species of cysts referable to the genus Peridinium were described by Wall (1965). Some of the specimens he described have a single wall; others double walls. Whether the single-wall type of cyst is derived from the double-wall type through decay, is not known. Classification onginoflagellates It is the consensus of modern biological interpreta- tion that dinoflagellates are algae. They are a group of unicellular organisms, some of which contain chlorophyll and are vagile and predatory. The botanical classification is followed in this thesis for the fossil dinoflagellates. This classification of the fossil dinoflagellates today generally conforms to botanical rules and taxonomic practice. Deflandre, in his work on fossil dinoflagellates, has classed them as Dinophyceae. Russian workers, Naumova and Timofeev, regard all hystrichospheres as plants, for taxo— nomic purposes. The question as to whether fossil dinoflag- ellates should be classed, for nomenclatural purposes, in 18 the animal or plant kingdoms has been adequately discussed by Downie, Williams and Sarjeant (1961) and Evitt (1963). They all agree that it is preferable to treat them under the botanical code. Classification of Acritarchs The classification of the acritarchs used in this thesis is that suggested by Downie, Evitt, and Sarjeant (1963). This is primarily an "artificial" grouping of genera of unknown biological relationships into morpholog-i ically similar categories. The International Code of 'Botanical Nomenclature is followed. The precise affinities of the acritarchs to algae, protozoans, protistans and the interrelationships of these groups themselves are in varying degrees of uncertainty. For practical purposes, acritarchs and other miscellaneous planktonic microfossils of organic composition and uncertain affinity should be dealt with under the same code as the dinoflagellates, and are refer- able to form genera and Species. Paleocecology and Ecology of Dinoflagellates Paleomicroplanktonic entities are recorded in rocks from Precambrian to Recent. Forms attributed to the Dino- phyceae have been reported (Tasch, 1963) from rocks of Permian age but there remains some question of the identifi— cation of these as palynomorphs and the author here has not examined them. The Dinophyceae are common in many of the was C.» At. 19 marine deposits from middle Jurassic and younger rocks. Today they are known to occur in marine, brackish, and fresh waters. There are very few records of fossil freshwater forms (Churchill and Sarjeant, 1962), and in practically all instances, fossil dinoflagellates are considered to be indi- cators of marine environments. The paleoecology of dinoflagellates is, as yet, little understood. It is only recently that modern dino- flagellate distribution, and even the distribution of many other groups of phytoplankton have become more than super- ficially understood. Obviously, in.the understanding of fossil dinoflagellate distributions, one must draw from the knowledge obtained in the study of living forms. It is pos- sible that with the advances in techniques of culturing phytoplankton, it may soon be possible to relate information derived from cultured populations to biogeographical prob- lems in natural marine environments. A satisfactory knowl- edge of the underlying biogeographical factors can be obtained by combining floristic studies with studies of cultured populations of dinoflagellates. Thus, the results of such experimental studies, may serve in interpreting dynamics of various species of phytoplankton in their natural environment. In the modern seas, the dinoflagellates rank second to the diatoms in the production of organic matter (Raymont, 1963). Occasionally, in response to unusually favorable w‘ .hu in“ '4 hKU .ph “hi it «h; L L 20 growing conditions, dinoflagellates may develop in profusion to form a "bloom." Dinoflagellates appear to flourish in warmer areas. They attain their greatest development in the lower latitudes. They may be the major element in the plank- ton for long periods of time. In the middle and high lati- tudes, they sometimes occur in abundance during the summer. The dinoflagellates are capable of feeble swimming, and this may be of ecological significance in enabling them to utilize dilute nutrients in the water, and by making pos- sible a better orientation to light. The spatial distribu- tion of dinoflagellates, as well as other phytoplankton, can be thought of as three dimensional, consisting of a latitu- dinal, longitudinal and a depth or vertical component. The distribution of dinoflagellates is governed by essentially the same variables that effect their abundance; salinity temperature, and nutrients. It is usually difficult to single out the most important factor in a given situation. Variations in these conditions can singly or in combination effect the morphology of individual species. For example, Chatton (1952) has noted that in warm waters some species have a tendency to develop spines and horns, which are usually absent or poorly develOped in cold water forms. Fritsch (1948) states that in the oceanic plankton the naked forms are abundant, whereas the neritic plankton is far richer in armoured forms. There are few dinoflagellates that are shore dwellers, but occasionally species of 21 Gymnodinium occur in the near-shore environment. The length of horns of Ceratium trichoceros is apparently regulated in some way by temperature, and perhaps by this mechanism it is able to regulate itself to the viscosity and specific grav- ity of the water. The thickness of the cellulosic plates also seems to vary with the temperature of the water. Ceratium platysome shows differences in shape of its horns, the flatter forms being typical of the variety living in warmer sub-tropical waters and the less-flattened horns being characteristic of colder seas. It is assumed that dinoflagellates are relatively free of the effects of bottom conditions. III. METHODS Sample Preparation Techniques Preparation of the Navarro shales and calcareous clay shales for microscopic analysis were carried out in a procedure similar to standard palynological maceration for the study of acid insoluble micro-organisms. To release the organic entities from the enclosing matrix, samples were treated according to the following procedure. 1. 2. 9. lo. 11. Dry 200 gram sample in oven in 80°C for 24 hours Crush sample into small fragments and mix thor- oughly Weigh 5 gram aliquot Treat 5 gram aliquot with 10% HCl for 10 minutes for removal of carbonates Wash residue Treat residue with 70% HF for 24 hours for removal of silicates Wash residue 3 times by centrifugation Treat residue with Schulze solution for 10-20 minutes Wash residue 3 times by centrifugation Treat residue with 10% NH OH for 5-8 minutes 4 Wash residue 3 times by centrifugation 22 In In ’4 (I) r9- L) (T :1“ 23 12. Mix residue in a dilute solution of Alcojet* for further reaction with humic material and removal of silt—size particles; centrifuge in Alcojet solution. 13. Wash residue 3 times by centrifugation 14. Perform specific gravity separation on residue using zinc chloride (sp. gr. 1.90) 15. Stain with Safrinin 0. Residues are stored in an aqueous solution of glycerin and phenol. Sample Analysis Four slides of each residue were made. One entire slide was examined in detail and types were recorded and established. A total of 5,000 dinoflagellates and acritarchs were observed in some instances on the first slide. A second slide was used to insure random sampling, for the determina- tion of relative abundance of the individual species. Rela- tive abundance of species were determined by the recording of not less than 200, where specimens were rare, and a min- imum of 500 where specimens were abundant. Also recorded were the relative abundance of pollen and spore groups or genera such as: bisaccates, Proteacidites, Classgpollis, triporates, tricolpates, Ephedra, and Sphagnum. *Alcojet - a patented detergent manufactured by Alconox Inc., New York, New York. IV. SYSTEMATIC DESCRIPTIONS Group ACRITARCHA Subgroup ACANTHOMORPHITAE Downie, Evitt and Sarjeant, 1963 Genus Micrhystridium Deflandre, 1937, emend. Downie and Sarjeant, 1963 Type species: M. (a1. Hystrichosphaera) inconspicuum (Deflandre, 1935) Cretaceous; France. Discussion: Micrhystridium is distinguished from Balti- sphaeridium on the size of the test. The two genera express two different size modes. The mean and modal diameter of the test of Micrhystridium is less than 20 microns. B315;- sphaeridium has a mean and modal diameter greater than 20 microns. The 20 micron size differentiation is purely an artificial dividing line, though Downie and Sarjeant (1963) consider the genera to express two natural size modes. Species formerly attributed to Micrhystridium.with distally Open tabular processes have been transferred to_Hystricho- _§phaeridium, and those whose surfaces are divided into fields by crests have been transferred to Cymatiosphaera. 24 “at... AK. A. :b 25 Migrhystridium fragile Deflandre, 1947 1947. Migrhystridium fragile Deflandre: p. 8, text-figs. 13-18. Middle Jurassic; France. Discussion: Micrhystridium fragile is restricted to speci- mens that have processes with narrow bases and generally sperical tests. Variation in number, length of processes, and shape of test amongst individual specimens of this species can exist. Processes are hollow, relatively long and slender, tapering towards closed distal tips. Process cavity communicates with test interior, though cavity does not extent to distal extremities of the processes. Dimensions: Average range of 4 specimens: diameter of test 16 to 21 microns; length of processes 10 to 16 microns. Remarks/Relationship_: Williams (1963) reports this species from the London Clay, Eocene, of England. It has also been recorded from the Middle Jurassic of-France (Deflandre, l947d; Valensi, 1947, 1954) and the Upper Jurassic of Britain (Sarjeant, 1959, 1960, 1961a). This species has little stratigraphic value because of its long stratigraphic range. Occurrence: ‘M, fragile is common in the Neylandville and Corsicana Formations; rare in the Kemp Formation, Austin composite section; rare in the Olmos and Escondido Forma- tions, Frio County, Texas. 26 Micrhystridium stellatum Deflandre, 1945 Pl. 1, Figs. 5-7 1945. Micrhystridium stellatum Deflandre: p. 65, pl. 3, figs. 16-19, Middle Silurian; France. Discussion: Navarro specimens of M. stellatum vary somewhat in shape of test and in process number and length. Processes are usually greater than or equal to the diameter of the test; 14-16 processes per test. Processes are simple, solid, straight or curved, acuminate or capitate distally. . Dimensions: Average range of 5 specimens: diameter of test 15 to 20 microns; length of processes 15 to 25 microns. Remarks/Relationships: Micrhystridium stellatum is described from the Wenlockian of France (Deflandre, 1945a) and Britain (Downie, 1959), and the Devonian of France (Deunff, 1954) Belgium (Stockmans and.Williere, 1960, 1962a, 1962b) Canada (Staplin, 1961) and (Cramer, 1964), the Permian of Britain (Wall and Downie, 1963), the Middle Jurassic of France (Valensi, 1953) and the Upper Jurassic of Britain (Sarjeant, 1959, 1960c, 1961a). Williams (1963) records the first Tertiary occurrence of this species from the London Clay, Eocene of Britain. Occurrence: JM. stellatum commonly occurs in the Corsicana Formation; rare in the Neylandville Formation in the Austin composite section. ‘A- -y‘ 1‘»- av L) I H ‘4. 1‘1. ‘H 27 ,Genus BaltiSphaeridium Eisenack 1958, emend. I.DOwnie and Sarjeant 1963 Type species: B. (a1. Ovum higpidum) longiSpinosum (Eisenack, 1931) Silurian; Baltic. Baltisphaeridium:hirsutumg(Ehrenberg,ul838) I.Pl. linig . 8-8a 1838. Baltigphaeridium hirsutum (as Xanthidium) (Ehrenberg); pl. 1, fig. 13, Cretaceous; Germany Discussion: One specimen referable to B, hirsutum was observed from the Navarro material. The species is conspic— uous from the surface pattern of the shell. Dimensions: Diameter of central body 57 x 60 microns; length of processes 20 to 25 microns. RemarksZRelationship_: B, hirsutum is reported from the Cretaceous of Germany (Ehrenberg, 1883) and the Cenomanian of Britain (Cookson and Hughes, 1964). Occurrence: Rare in Corsicana Formation, Austin composite section. Baltisppaeridium Sp. 1 Sp. nov. *,P1. 1; Figs. 9—11 Diagnosis: Central body sub-circular to elliptical, possess- ing widely separated processes. Processes acuminate, solid; number of processes, 10-14. Wall of central body smooth. 28 Holotypg: Pb. 4632, slide s-2, coord. 41.8 x 108.0; Neylandville Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 60 by 50 microns; length of processes 30 to 33 microns. Average range of 3 Specimens: diameter of central body 55 to 63 by 50 to 55 microns; length of processes 10 to 33 microns. Remarks/Relationship_: The central body of Specimens of this Species is subject to folding and distortion. The small number of processes and their distinctly acuminate character make this species readily identifiable. A pylome is not observed in any of the specimens examined. The species is restricted to the Neylandville Formation and may be stratigraphically Significant in the Austin composite section. Occurrence: Common in the Neylandville Formation, Austin composite section. Baltisphaeridium sp. 2 sp. nov. “Pl. 2, Figs. 3-4a Diagposis: Central body elongate, possessing numerous solid, thin, hair-like sinuous processes. wall of central body finely granular. Holotype: Pb. 4513, slide 5, coord. 33.8 x 94.2; Corsicana Formation (Maestrichtian), Austin composite section. '29 Dimensions: Holotype: length of central body 35 microns; width of central body 17 microns; length of processes 10 to 15 microns. Average range of 3 specimens: length of cen- tral body 29 to 35 microns; width of central body 17 to 20 microns; length of processes 8 to 12 microns. Remarks/Relationships: Baltisphaeridium sp. 2 is somewhat Similar to Baltisphaeridium pilosum (Ehrenberg, 1943) in Shape of central body and in bearing Slender processes, but B, sp. 2 is much smaller in size and the processes are not hollow as in B, pilosum. Baltipphaeridium sp. 2 is close to B, sp. 3 in size and Shape of central body, and in wall ornamentation, but differs from that species in character of the process. B, sp. 2 usually occurs in abundance when encountered in a sample. Occurrence: Abundant in Corsicana Formation; common in Kemp Formation, Austin composite section; rare in Escondido Forma— tion, Frio County, Texas. Baltisphaeridium Sp. 3 sp. nov. ‘.P1" 2, Figs..l-2b Diagnosis: Central body elongate, possessing numerous solid, Short, straight processes which are truncate distally. Wall of central body finely granular. Holotype: Pb 4647, Slide 2, coord. 31.5 x 101.2; Kemp Formation (Maestrichtian), Austin composite section. 30 Dimensions: Holotype: length of central body 33 microns; width of central body 17 microns; length of processes 6 to 7 microns. .Average range of 4 Specimens: length of central body 30 to 34 microns; width of central body 15 to 18 microns; length of processes 4 to 7 microns. RemarkSZRelationshipS: Baltisphaeridium sp. 3 is similar to B, Sp. 2 in size and shape of central body, but the processes of this species are not hair-like as in B, Sp. 2. The mor- phologic features of this species are relatively simple, and the short truncate processes make it readily distinguishable from B, sp. 2. This species appears to be restricted to the Kemp Formation and it may prove to be a marker for the upper part of the formation. Occurrence: Common in the Kemp Formation, Austin composite section. Subgroup HERKOMORPHITAE Genus Cymatiosphaera O. Wetzel, 1933 Type species: B, radiata O. Wetzel, 1933, Cretaceous; Germany. Cymatiosphaera radiata O. Wetzel, 1933 P1. 2, Figs. 5-9 1933. Cymatiosphaera radiata O. Wetzel: p. 27, pl. 4, fig. 9, Senonian; Germany. I i U) l(" f) (‘1 Il‘l 31 Discussion: The holotype of g, radiata from the north German Senonian flint has not been examined by the writer, but specimens here referable to that species seem to fit reasonably well the circumscribed limits of the species. Dimensions: Average range of 6 specimens: overall diameter 40 to 45 microns. RemarkSZRelationshipg: g, radiata has been described by O. Wetzel (1933) from a north German Senonian flint. The species also has been recorded from the Albian and.Cenomanian of Australia, Cookson and Eisenack (1960). Occurrence: Abundant in Neylandville and Corsicana Forma- tions; common in Kemp Formation, Austin composite section; common in Olmos and Escondido Formations, Frio County, Texas. Subgroup Uncertain Genus Palaeostomocystis Deflandre, 1935 Type Species: Palaeostomopystis reticulata Deflandre, 1935, Cretaceous; France. Palaeostomogystis sp. 1 sp. nov. Diagnosis: Test ellipsodial, both sides rather evenly convex, narrowing towards a slightly sunken pylome at the apex. Wall Slightly thickened around pylome. Wall extra- vermiculate. U..— 2.- PIA~ III 32 Holotype: Pb 4504, slide 5, coord. 43.8 x 95.5; Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: length of test, 31 microns, width of test, 20 microns. Range of 4 specimens: length of test 27 to 32 microns; width of test 17 to 21 microns. Remarks/Relationships: Palaeostomocygtis sp. 1 is similar to B, ppiculata Cookson and Eisenack (1960) from the Campan- ian of Australia in shape and nature of pylome. Palaeo- stomocystis sp. 1 differs from that species in not possessing spinules in the anterior and posterior regions, in being smaller in size, and in possessing an ornamented shell membrane. Occurrence: Common in Neylandville Formation; abundant in Corsicana Formation, Austin composite section; rare in Olmos and Escondido Formations, Frio County, Texas. Class CHLOROPHYCEAE Family Uncertain Genus Palambages O. Wetzel, 1961 Type species: Palambages morulosa O. Wetzel, 1961. Upper Cretaceous; EurOpe. Discussion: The genus Palambages was first described in 1961, for those colonies or spherical bodies composed of many oval cells. Comparable colonies and a new species have since been recorded from Maestrichtian deposits in Poland 33 (H. Gorka, 1963) and three forms, Palambages Forma A, Forma B and Forma C, are described by Manum and.Cookson (1964) from the lower Upper Cretaceous deposits in Graham and Ellef Ringes Islands, Arctic Canada. The present knowledge of the morphologic characteristics of this genus does not support assignment of this genus to the dinoflagellates at the present time. The stratigraphic range of the genus is known only to be in the Upper Cretaceous. Palambages Forma A Manum and.Cookson, 1964 P1. 2, Figs. 10-12 Pl. 3, Fig. 2 1964. Palambages Forma A Manum and Cookson: p. 24, p1. VII, figs. 3-6. Cretaceous; Graham Island, Arctic Canada. Discussion: The number of cells per colony is variable in Specimens observed from the Navarro Group. The walls of the cells are finely to coarsely granular. Dimensions: Range of 8 specimens: overall diameter 40 to 55 microns. Remarks/Relationship_: Palambages Forma A is described by Manum and Cookson (1964) from the lower Upper Cretaceous deposits in Graham and Ellef Ringes Island, Arctic Canada. Cookson (1965) reports this species from the lower Upper and Upper Cretaceous (Senonian) of south Australia. Occurrence: Abundant in Neylandville Formation; common in Corsicana and Kemp Formations, Austin composite section. 34 Palambages deflandrei Gorka, 1963 ' ',Pl. 3, Fig. 1 1963. Palambages deflandrei Gorka: p. 76, pl. XI, fig. 2. Upper Cretaceous (Maestrichtian); Poland. Discussion: This species is characterized by clusters of oval, membranous cells with peripheral openings. Wall granular. Dimensions: Range of 3 specimens: overall diameter 45 to 60 microns. Remarkg/Relationship_: Palambages deflandrei and Palambages Forma A are the only two species of the genus observed in the Navarro Group. In spite of the nondescript morphologies of these two species, they are easily distinguishable from each other. Occurrences: Rare in Neylandville Formation; common in Corsicana and Kemp Formations, Austin composite section; rare in Olmos and Escondido Formations, Frio County, Texas. Class DINOPHYCEAE Discussion: The Class Dinophyceae embraces all fossil dino- flagellates and the typical hystrichospheres. Downie, Evitt and Sarjeant (1963) define hystrichospheres as fossils iden- tified as dinoflagellates that are generally similar to Hystrichosppaera; that is, forms with a spherical to ellip- soidal or lenticular central body which bears several to 35 many more or less spine-like radiating processes. The four criteria considered most critical by Evitt (1961) in demon- strating dinoflagellate affinity are: 1. Presence of a transverse furrow, with or without a longitudinal furrow. 2. Evidence of tabulation by alignment or grouping of ridges or processes according to the plate arrangement of typical thecate dinoflagellates. 3. Presence of an archeopyle. 4. Overall Shape; an extreme "peridinioid" outline is indicative of dinoflagellate affinities, but it should not be considered conclusive without supporting evidence. on the basis of these criteria, Evitt (1963) proposed two new dinoflagellate families, the Hystrich0§phaeridiaceae and Areoligeraceae and the emendation of the family Hystricho- sphaeraceae (O. Wetzel). These families are based on the Shape of the test, the type of symmetry, the position of the processes relative to the plates, and the nature of the archeopyle. 36 Family Hystrichosphaeridiaceae Evitt Genus Oliggpphaeridium Davey and Williams in Davey et al., 1966 (p. 70) Type species: Xanthidium tubiferum complex White, 1842. Upper Cretaceous; England. OligOSphaeridium complex (White) emend. Davey and Williams in Davey et al., 1966 P1. 3, Fig. 12 1842. OligOSphaeridium (a1. Xanthidium tubiferum) complex White: p. 39, pl. 4, div. 3, fig. 11. Upper Cretaceous; England. Discussion: Specimens referable to B, complex from the Navarro Group conform in every respect to the specific description of the species. Processes 17—18 in number (12-13 remain when the epithema is absent). Dimensions: Range of 5 specimens: diameter of central body 31 to 37 microns; length of processes 28 to 32 microns. Remarks/Relationships: OligOSphaeridium complex has been recorded from the Upper Cretaceous of England (White, 1842, 1844a), Belgium (Lejuene-Carpentier, 1940), France (Firtion, 1952; Valensi, 1955b), Germany (Eisenack, 1958c; Gocht, 1959), the London Clay, Eocene of Britain (Davey at al., 1966), the Neocomian of Germany (Gocht, 1959) and the Lower and Upper Cretaceous of Australia (Deflandre and Cookson, 1955; and.Cookson and Eisenack, 1958). I have also seen 37 this species in the Rocky Mountain Upper Cretaceous strata. The species, therefore, has a worldwide distribution. Occurrence: Rare in Neylandville Formation; common in Corsicana Formation; rare in Kemp Formation of the Austin composite section; rare in Olmos and Escondido Formations, Frio County, Texas. Genus Tanyosphaeridium Davey and.Williams in Davey et al., 1966 (p. 98) Type species: Tanyosphaeridium variecalamum Davey and Williams in Davey et al., 1966. Upper Cretaceous (Cenomanian); England. Tanyosphaeridium sp. 1 Sp. nov. Pl. 5, Figs. 4-4a, 6-7 Diagnosis: Central body elongate, composed of thin endo- phragm and finely granular periphragm. Processes consist of smooth periphragm. The processes are oval in cross section, long, slender, hollow, and do not communicate with the interior of the central body. Processes with fairly broad base proximally; distally, processes open and greatly expanded and with entire margins. Precingular fields bear two processes. Archeopyle apical, edges not zig-zag; defined In? margins of 6 precingular fields. Cingulum does not possess processes. Number of processes, 25-32. Holotype: Pb 4518, slide 4, coord. 32.2 x 89.3; Corsicana Formation (Maestrichtian), Austin composite section. 38 Dimensions: Holotype: length of central body 34 microns; width of central body, 23 microns; length of processes 16 to 18 microns. RemarkSZRelationships: Tanyosphaeridium Sp.l is closest to T, variecalamum Davey and‘Williams (Davey at al., 1966) but differs from that species in having processes that are more greatly expanded distally, and in width-length ratio of the central body. 2, sp. 1 is shorter and wider in the many specimens observed. Tanyosphaeridium sp. 1 is Similar to ‘3. isocalamus Deflandre and Cookson (1955) in outline, and in bearing long slender processes, but the processes in that species have clearly truncate apices which are not expanded distally. That species also differs in having a punctate wall. .1. sp. 1 occurs in the Red Bank Formation (Maestrich- tian) of New Jersey. Occurrence: Abundant in Corsicana; common in Kemp Formation, Austin composite section; common in Escondido Formation, Frio County, Texas. Tanyosphaeridium sp. 2 sp. nov. P1. 5, Fig. 5 Diagnosis: Central body ellipsoidal-elongate, composed of thin endophragm and a thin, finely granular periphragm. Processes consist of smooth periphragm. The processes are oval to elliptical in cross section; long, slender. Pro— cesses taper distally from a fairly broad base. Distally processes are truncate and not expanded. Archeopyle apical; 39 margin not zig-zag, defined by margins of 6 precingular fields. Precingular fields bear one or two processes. Number of processes 25-31. Holotype: Pb 4632, slide s—l, coord. 34.2 x 99.2; Neyland- ville Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: length of central body 31 microns; width 25 microns; length of processes average 10 to 13 microns. Range of 6 specimens: length of central body 27 to 34 microns; width of central body 22 to 26 microns; length of processes 9 to 14 microns. RemarksZRelationship_: Tanypsphaeridium sp. 2 is similar to .2. variecalamum Davey and Williams (Davey et al., 1966) in bearing truncate processes and in general shape of the cen— tral body. It differs from that species in having a con- sistantly wider central body. 3, sp. 2 is restricted to the Neylandville Formation in the Austin composite section, and may prove to be of stratigraphic importance locally. Occurrence: Common in Neylandville Formation, Austin composite section. Genus Polysphaeridium Davey and Williams in Davey et al., 1966 (p. 91) Type Species: Polysphaeridium subtile Davey and Williams in Davey et al., 1966, Eocene (Ypresian); England. 4O Polysphaeridium sp. 2 Sp. nov. Pl. 4, Figs. 8-10 Diagnosis: Central body subcircular, consisting of rela- tively thick endophragm and thin finely reticulate periphragm. Processes numerous short, tapering slightly distally. Processes truncate distally, and with denticulate apices. The processes are composed of finely fibrous periphragm. Holotype: Pb 4632, slide 4, coord. 32.2 x 107.2; Neyland- ville Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: Diameter of central body 51 by 57 microns; length of processes, 5.7 to 6 microns. Range of 3 specimens: diameter of central body 50 to 55 microns by 55 to 58 microns; length of processes 5 to 8 microns. Occurrence: Common in Neylandville Formation, Austin composite section; rare in Olmos Formation, Frio County, Texas. Polysphaeridium sp. 1 sp. nov. P1. 6, Figs. 8, 10 Diagnosis: Central body subspherical, consisting of thin smooth endophragm and periphragm. Processes numerous, long, slender, tubular; circular to elliptical in cross section. Processes taper distally and are somewhat constricted before flaring abruptly at the extremities. Distal margins of process entire, slightly recurved. 41 Holotype: Pb 4518, slide 2, coord. 35.7 x 90.2; Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: Diameter of central body 57 by 58 microns; length of processes 18 to 20 microns. Range of 3 Specimens: diameter of central body 55 to 60 microns; length of process 15 to 22 microns. Remarkp/Relationships: Polysphaeridium sp. 1 is Similar to Polysphaeridium sp. 3 in wall character and termination of processes, though, in this species the processes are of greater length. The thin-walled character of this species is subject to distortion and folding. Tabulation has not been determined. Occurrence: Rare in Neylandville Formation; common in Corsicana Formation; rare in Kemp Formation, Austin compos- ite section; rare in Olmos and Escondido Formations, Frio County, Texas. Polysphaeridium sp. 3 Sp. nov. P1. 5, Figs. 8—10 P1. 6, Fig. 1 Diagnosis: Central body spherical to subspherical, possess- ing a thin smooth endophragm and periphragm. Processes numerous, tubular, nearly circular in cross-section. Processes taper slightly distally and flare abruptly rather markedly at extremities. Distal margins of processes entire. The archeopyle was not observed. 42 Holotype: Cp_l, Slide s-l, coord, 43.4 x 97.7; Kemp Forma- tion (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 30 by 32 microns; length of processes 6 to 8 microns. Range of 4 specimens: diameter of central body 29 to 33 microns; length of processes 6 to 9 microns. Remarks/Relationships: The thin wall of the central body of this species is subject to folding and distortion. The Spherical, thin-walled central body and greatly expanded process tips makes the Species easily recognizable. B, sp. 3 is similar to B, sp. 1 in having a Somewhat spherical thin-walled central body and in possessing greatly eXpanded process tips, though the processes of B, sp. 3 are more numerous than in that species and are shorter in length. .B. Sp. 3 appears to have a restricted distribution in the upper part of the Kemp Formation, and may prove to be a marker fossil for that part of the Navarro. Occurrence: Common in Kemp Formation, Austin composite section. Polysphaeridium sp. 4 sp. nov. Pl. 6, Figs. 9, ll Diagnosis: Central body subspherical, consisting of thin endophragm and thin, finely granular periphragm. Processes very numerous, tubular, subspherical in cross-section; pro- cesses taper slightly toward extremities, truncate and expanded Slightly distally. 43 Holotype: Pb 4575, slide 3, coord. 47.5 x 101.8. Neyland- ville Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of centralbody 28 by 35 microns; length of processes 10 to 12 microns. Range of 3 specimens: diameter of central body 30 to 35 microns; length of processes 9 to 12 microns. Remarks/Relationships: Polysphaeridium sp. 4 is similar to sp. 1 in Size and wall structure, but differs in having the greatly distal expanded processes. Tabulation has not been determined. Archeopyle was not observed. Occurrence: Common in Neylandville Formation, Austin Compos— ite section. Genus Bystrichosphaeridium Deflandre 1937, emend. Davey and Williams in Davey et al., 1966 (p. 55) Type species: (Hystrichosphaeridium (Xanthidium) tubiferum (Ehrenberg), 1838. Upper Cretaceous; Germany. Hystrichosphaeridium tubiferum (Ehrenberg), emend. Davey and Williams in Davey et al., 1966 (p. 56) Pl. 3, Figs. 9-11 Pl. 4, Figs. 1-3 1838. Hystrichosphaeridium tubiferum (Ehrenberg): pl. 1, fig. 16. Senonian; Germany. Discussion: The specimens here referred to B, tubiferum conform to the specific description of the type species. The processes of the Navarro forms usually number 29-30. .3 I.“ C. 44 and are of various diameters. The sulcal processes are reduced in diameter and length. The reflected tabulation is 4 apical, 6 precingular, 6 cingular, 5 postcingular, l poste— rior intercalary, l antapical plates. The archeopyle is usually always identifiable. Dimensions: Range of 5 specimens: diameter of central body 37 to 43 microns; length of processes 17 to 25 microns. Remarks/Relationships: Hystrichosphaeridium tubiferum is recorded from the Senonian of Germany by Ehrenberg (1838a), Ypresian of Belgium, Pastiels (1948), the Oligocene of Germany, Gocht (1952); BroSius (1963), the Oligocene to Middle Miocene of Germany, Gerlach (1961), the London Clay, Eocene of Britain, Davey et a1. (1966). Occurrence: Abundant in Corsicana Formation, Austin compos- ite section; common in Escondido Formation, Frio County, Texas. Hystrichosphaeridium stellatum"Maier, 1959 P1. 4, Figs. 4-4a 1959. Hystrichosphaeridium stellatum Maier: p. 320-1, pl. 33, figs. 3-4. Oligocene; Germany. Discussion: The morphology of the specimens from Texas tend to vary somewhat from the type material of Maier. They do compare well with those specimens from Albian to Cenomanian deposits of Western Australia, referred to by Cookson and Eisenack (1962), and the Upper Gault and Greensand 45 (Cenomanian) of Britain described by Cookson and Hughes (1964). Because of distinctive difference in age of the Texas and European formas and those from Australia, there is possibly an unrecognizable Specific difference from Maier's material. Dimensions: Range of 3 specimens: diameter of central body 34 to 40 microns; length of processes 13 to 19 microns. RemarkS/Relationship_: (Hystrichosphaeridium stellatum is recorded from the Oligocene—Middle Miocene of Northwest Germany (Maier, 1959), and the Albian-Cenomanian of Austra— lia (Cookson and Eisenack, 1962). Occurrence: Common in Corsicana Formation, Austin composite section. Hystrichosphaeridium patulum Davey and WiIliams in Davey et al., 1966 (p. 60) Pl. 5, Figs. 1-3 1966. Hystrichosphaeridium pptulum Davey and‘Williams in Davey at al.: p. 60, pl. 10, fig. 5. Paleocene; Britain. Discussion: Specimens referred to B, patulum closely con— form to the specific description and illustration of that species. Dimensions:l Range of 6 Specimens: diameter of central body 14 to 16 microns; length of processes 5 to 7 microns. RemarkSZRelationships: Hystrichosphaeridium patulum is recorded from the London Clay, Eocene of Britain, Davey et a1. (1966). 46 Occurrence: Common in Corsicana Formation, Austin composite section. Rare in Escondido Formation, Frio County, Texas. Hystrichpphaeridium sp. 1 sp. nov. Diagnosis: Central body spherical, consisting of moderately thick endophragm and thin striate periphragm. Processes con- sist of fibrous periphragm. Processes taper from a broad base and are truncate distally; distal margins of processes denticulate. Holotype: Pb 4670, slide 1, coord. 45.5 x 96.2. Neyland- ville Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 30 microns; length of processes 15 to 17 microns. Range of 3 specimens: diameter of central body 30 to 35 microns; length of processes 15 to 18 microns. Remarks/Relationships: the striate periphragm of the cen— tral body and the fibrous nature of the processes character- ize this species. Occurrence: Common in Neylandville Formation, Austin compos- ite section. Hystrichosphaeridium Sp. 2 sp. nov. Pl. 7, Figs. 5-7 Diagnosis: Central body subcircular. Processes wide, short, and taper distally from a broad base; ellipitcal in cross- section. Periphragm punctate. Archeopyle margin zig—zag. 47 Holotype: Pb 4632, slide s-2, coord. 35.3 x 92.0. Neyland- ville Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 37 by 45 microns; length of processes 7 to 8 microns. Average dimen- sions of 6 measured specimens: diameter of central body 35 by 40 microns; length of processes 6 to 8 microns. RemarkpZRelationships: the short processes with broad bases distinguish this species from others in the genus. In some, the processes appear to be closed distally. Occurrence: Rare in Neylandville Formation, Austin compos- ite section. E’Hystrichosphaeridium sp. 3 sp. nov. P1, 6, Figs. 2—7 Diagnosis: Central body subspherical to elliptical, bearing numerous pairs of slender rod-like processes which are sur- rounded by a thin membranous-like structure; membranous structure also extending to tips of neighboring processes. Holotype: Pb 4521-8, slide 22A. coord. 38.0 x 90.8. Corsicana Formation (Maestrichtian), Austin composite sec- tion. Dimensions: Holotype: diameter of central body, 67 by 57 microns; length of processes 7 microns. Range of 4 speci- 1mens: diameter of central body 68 to 75 by 55 to 67 microns; length of processes 6 to 8 microns. 48 Remarks/Relationships: This species is placed questionably in Hystrichosphaeridium. The processes are numerous and are distally covered with a thin membrane which tends to sur- round the central body. The archeopyle position has not been determined. Occurrence: Common in Corsicana Formation, Austin composite section. Genus Cleisto§phaeridium Davey et a1, 1966 (p. 166) Type spgcies: Cleistosphaeridium diversippinosum Davey et al., 1966, Eocene; England. Cleistosphaeridium sp. 1. Sp. nov. Pl. 8, FigSo' 1-2 Diagnosis: Central body spherical with finely granular wall, and bearing numerous solid, dagger-like processes. Processes closed distally, acuminate; some bifid or blunt. Archeopyle apical, with zig-zag margins, which is formed by 6(?) pre— cingular plate-fields. Length of processes traversed by slender fibrils. Possibly two processes per precingular plate fields. Holotype: Pb 4542, Slide 1, coord. 31.0 x 92.8. Kemp Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 43 microns; length of processes 17 to 19 micrpns. Range of 6 specimens: 49 diameter of central body 39 to 45 microns; length of pro- cesses 15 to 22 microns. Remarkslgelationshipsz Processes appear regularly arranged, but the tabulation is not determinable. 9, sp. 1 is similar to B, disjunctum Davey et a1. (1966) in Size and granular central body, though the processes of g, sp. 1 appear to be solid. The processes of 9, sp. 1 are characterized by slender longitudinal fibrils, which are not described in B, disjunctum. The length of the processes is usually constant in an individual. Occurrence: Common in Corsicana Formation; rare in Kemp Formation Austin composite section; rare in Escondido Forma- tion, Frio County, Texas. Forma F Gen. nov. Diagnosis: Chorate cysts with spherical to subspherical central body possessing two types of processes. There are numerous fine processes usually closed distally covering the central body, and a single large hollow antapical process which is open distally. Archeopyle precingular, margin undulating, not zig-zag. Type species: Forma F. sp. 1 Sp. nov. Corsicana Formation (Maestrichtian), Austin composite section. Remarkiselationships: This genus is similar to Diphyes Cookson (1965) in possessing two types of processes, but 50 differs from that genus in having a precingular rather than apical archeopyle. The precingular archeopyle and large antapical processes enable orientation of specimens of this species. The smaller processes are simple, slender, and usually taper distally, and are usually closed distally. Forma F sp. 1 Gen. et sp. nov. Pl. 8, Figs. 3-10 Diagnosis: Subspherical to spherical central body. Endo- phragm thin; periphragm thin, with sinuous, fine striations. Central body covered with numerous filamentous or hair-like processes which taper distally to a narrow point from a broad base, which are usually closed distally; some are Open. Large antapical process hollow, Open distally and with distal margin denticulate. Holotype: Pb 4519, slide 6, coord. 36.7 x 104.5. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 45 by 50 microns; length of filamentous processes 18 to 22 microns; length of antapical process 20 microns; width 10 microns. Range of 8 specimens: diameter of central body 42 to 58 microns; length of processes 15 to 27 microns. Remarks/Relationships: This Species closely approximates the figured specimen of Hystrichosphaeridium monstrosum Tasch et a1. (1964), though no mention is made of ornamenta- tion of the central body in the specific description nor of 51 archeopyle position. The illustrated specimen also does not Show two opposite, large, polar processes as originally described. This interpretation probably is due to a mis- interpretation of the morphology by Tasch. The writer has examined samples from Tasch's study area, and specimens of these forms show a precingular archeopyle and only one polar process. Davey et a1. (1966) incorrectly refer B, monstrosum to the genus Diphyes. B, monstrosum should be reassigned to Forma F. Occurrence: Common in Corsicana Formation, Austin composite section; rare in Escondido Formation, Frio County, Texas. Genus Diphyes Cookson, 1965, emend. Davey and Williams in Davey et al./ 1966 (p. 95) Type species: Diphyes (Hystrichosphaeridium) colligerum (Deflandre & Cookson), 1955, Eocene; Australia. Diphyes colligerum (Deflandre & Cookson) emend. Davey and.Williams in Davey et al., 1966 P1. 9, Figs. 1-2 1955. B, (a1. Hystrichosppaeridium) colligerum Deflandre & Cookson: p. 278, pl. 7, fig. 3. Discussion: The specimens B, colligerum are in rather close agreement to the amended specific description by Cookson (1965, p. 86). The nature of the distal portion of the smaller processes though, appears to be in doubt. Cookson states that it is impossible to trace the cavity along the 52 whole length of the appendages owing to the narrowness of their distal portions and the relative thickness of their walls, though the cavities do appear to communicate with that of the shell. The processes of specimens observed and illustrated here do not communicate with the interior of the central body as is stated in the holotype description. Davey et a1. (1966) state that the process of this species in their material do not open to the interior. It is quite difficult to determine in even well-preserved specimens from the Navarro if the distal extremities are open or closed. They taper to a very narrow terminal end, and are bluntly- pointed, slightly capitate, but not tubular. The smaller processes are less cylindrical at the bases, and taper to a more narrow point than those illustrated in the type spec- imen. The processes also appear to be more flexuous and are traversed by very fine fibrils, in the Navarro forms. Stanley (1965, p. 231, pl. 24, figs. 7, 8) illustrates a specimen which he considers conspecific with B, colligerum. Stanley's specimens appear to have a close affinity to or are conspecific with forms observed in the Navarro. Dimensions: Range of 3 specimens: Diameter of central body 35 by 40 microns; length of filamentous processes 14 to 16 microns. RemarksZRelationships: Diphyes colligerum is reported from the Upper Cretaceous and Eocene of Australia and in England from the Eocene (Davey et al., 1966). Stanley (1965) reports the species from the Paleocene of South Dakota. 53 Occurrence: Common in Corsicana Formation; rare in Kemp Formation, Austin composite section. Genus Forma A Gen. nov. Diagnosis: Chorate cysts with spherical to subspherical central body. Processes numerous, of various sizes, intra- tabular, solid or hollow. Archeopyle precingular, polygonal; formed by loss of ep. hema consisting of a single plate field bearing several processes; margin never zig-zag. Type species: Forma A sp. 1 sp. nov. Corsicana Formation (Maestrichtian), Austin composite section. Remarkiselationships: This genus is somewhat similar to Cordosphaeridium Eisenack in having processes composed of elongated fibrous strands, and that the archeopyle is formed from loss of one field and has a polygonal outline with angular corners. The archeopyle of Cordospnaeridium is apical. In some specimens of the species of Forma A, the archeopyle may appear to be apical due to differential com- pression, but in inflated specimens, it can be shown to be definitely precingular. The number and size of processes can vary considerably within the genus, but are usually constant within a species. A fused polar appendage is usually present just anterior to the archeopyle. 54 Forma A Sp. 1 Gen. et sp. nov. P1. 9, Fig. 12 P1. 10, Figs. l-lO Diagnosis: Central body subspherical composed of smooth endophragm and fibrous periphragm, from which the processes arise. Processes numerous, slender, hollow, oval in cross- section. Processes taper from a broader base, then flare distally; with recurred denticulate terminal ends. Wall of processes traversed by slender fibrils which extend from apex to base. The fibrils extend from the central body where they form a faint linear-reticulate pattern. There are 7—9 processes per field. Holotype: Pb 4504, slide 5, coord. 38.4 x 92.7. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 57 by 57 microns; length of processes 15 to 17 microns. Range of 6 specimens: diameter of central body 50 to 60 microns; length of processes 13 to 20 microns. Remarks/Relationships: Forma A sp. 1 is similar to Forma A sp. 2 and Forma A sp. 3 in having a fibrous periphragm. Forma A sp. 1 is close to Forma A sp. 2, but is distinguished from that species in having a thicker endophragm and being larger in size. In some samples Forma A sp. 1 occurs in great abundance and may dominate the assemblage. This abundance may prove to be of value in local correlations. 55 Occurrence: Rare in Neylandville Formation; abundant in Corsicana Formation; common in Kemp Formation, Austin compos- ite section; common in Olmos and Escondido Formations, Frio County, Texas. Forma A sp. 2 Gen. et Sp. nov. P1. 11, Figs. l-3a P1. 12, Figs. 1-3 Diagnosis: Central body subspherical, composed of smooth relatively thick endophragm and fibrous periphragm, from which the processes arise. Processes numerous, slender, tubular, oval in cross-section. Processes taper from a broad base then flare distally, and with aculeate tips which sometimes are recurved. Wall of processes traversed by slender fibrils which extend from apex to base. The fibrils extend from the central body where they form a linear- reticulate pattern. There are 3-5 processes per field. Holotype: Pb 4513, slide 3, coord. 38.6 x 99.0. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 74 by 80 microns; length of processes 29 to 30 microns. Average dimensions of 5 specimens: diameter of central body 70 to 82 microns; length of processes 26 to 33 microns. Remarks/Relationship_: Forma A sp. 2 is closest to Forma A Sp. 1, though it is distinguished from that species in hav- ing a thicker endophragm, is larger in size, and possesses fewer processes per field. 56 Occurrence: Rare in Neylandville Formation; common in Corsicana Formation, Austin composite section. Forma A sp. 3 Gen. et sp. nov. Diagnosis: Central body subspherical, composed of smooth endophragm and fibrous periphragm, from which the processes arise. Processes densely cover the central body. Processes short acuminate, usually closed distally; some open. Wall of processes traversed by slender fibrils which extend from apex to base. The fibrils extend from the central bOdy where they form a finely linear-reticulate pattern. Number of processes per field not determined, but very numerous. Holotype: Jc-40, slide 3, coord. 41.3 x 98.3. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 68 by 70 microns; length of processes 2.8 to 3.0 microns. Average dimensions of several Specimens: diameter of central body 52 by 70 microns; length of processes 2 to 4 microns. RemarksZBelationships: This Species is Similar to Forma A sp. 1 in size, outline and ornamentation of periphragm, though Forma A sp. 3 is easily distinguished by its small processes. Occurrence: Abundant in Corsicana Formation, Austin compos- ite section; common in Escondido Formation, Frio County, Texas. 57 Genus Cordosphaeridium Eisenack, 1963 emend. Davey and Williams.in DaVey et al., 1966 (p. 83). Type Species: Cordosphaeridium (Hystrichosphaeridium) inodes (Klumpp) 1953. Eocene; Germany. Cordosphaeridium inodes (KlumPP, 1953) P1. 4, Figs. 5-7 1953. Cordosphaeridium (BB. HystrichOSphaeridium) inodes (Klump) p. 391, pl. 18, figs. 1-2. Eocene; Germany. Discussion: The Navarro forms referred to Cordospnaeridium inodes conform to the specific description of the species given by Klummp. Dimensions: Range of 5 specimens; diameter of central body 51 to 60 microns; length of processes 20 to 24 microns. Remarks/Relationships: Cordosphaeridium inodes has been previously recorded from the Eocene of Germany (Klummp, 1953) and Victoria (Deflandre and Cookson, 1955), the middle Eocene and middle Miocene of Northwest Germany (Gerlack, 1961) and the upper Oligocene of Germany (Brosius, 1963), the Cannon Ball Member, Fort Union Formation of South Dakota (Stanley, 1965), the Eocene of Britain (Davey et al., 1966). Occurrence: Common in Corsicana Formation; common in Kemp Formation, Austin composite section; common Escondido Forma- tion, Frio County, Texas. 58 Cordosphaeridium fibrospinosum Davey and.Williams in Davey et al., 1966 (p. 86) ‘ “ P1. 12, Figs. 4-5a P1. 13, Fig. 1 1966. Cordosphaeridium fibrospinosum Davey and Williams in Davey et al.: p. 86, pl. 5, fig. 5, Eocene; Britain. Discussion: Navarro specimens of this species closely con- form to the description and illustration given by Davey et a1. (1966). Dimensions: Range of 4 Specimens: diameter of central body 65 to 70 microns. Length of processes 28 to 32 microns. Remarks/Relationships: Stanley (1965, p. 231, pl. 25, figs. 1-6) illustrates specimens which he refers to Bystrichosphaeridium inodes Klummp. His illustration and description is close to Q, fibrospinosum and to the Navarro specimens observed here, and probably should not be assigned to E, inodes. Occurrence: Abundant in Corsicana Formation; abundant in Kemp Formation Austin composite section; common in Escondido Formation, Frio County, Texas. Cordosphaeridium sp. 1 sp. nov. "Pl. 13,‘Figs. 2—4 Diagnosis: Central body subspherical, composed of smooth endophragm and fibrous periphragm. The periphragm forms numerous broad relatively short processes which consist of slender fibrils which run from the apex to the base. 59 Processes are open and slightly expanded distally; ellipti- cal in cross-section. Outline of archeopyle polygonal. Holotype: Pb 4632, slide s-5, coord. 36.7 x 101.8. Neyland- ville Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 60 microns; length of processes 17 to 20 microns. Average dimensions of 3 specimens; diameter of central body 55 to 67 microns; length of processes 15 to 20 microns. Remarks/Relationships: This species is close to Cordosphae- ridium fibrospinosum Davey et al., 1966, but differs in having shorter and less wide processes. 9, sp. 1 is re— stricted to the Neylandville Formation in the Austin compos- ite section, and may be cOnSidered as an index species of. that formation on the basis of our present evidence. Occurrence: common in Neylandville Formation, Austin com— posite section. Genus Callaiosphaeridium Davey and Williams in Davey at al., 1966 (p. 103) Type species: Bystrichosphaeridium asymmetricum Deflandre & Courteville, 1939. Upper Creataceous; France. Callaiosphaeridium cf. asymmetricum (Deflandre & Courtville) P1. 13, Figs. 5-7 Discussion: Navarro specimens referable here to B, asyg- metricum agree in most respects to the specific description given by Deflandre & Courtville (1939). 60 Dimensions: Average range of 3 specimens: diameter of central body 45 to 50 microns; length of cingular processes 15 to 22 microns. RemarksZRelationshipy: Davey et a1. (1966) illustrate Cenomanian forms assigned to B, asymmetricum which possess an elevation of the ribs joining the hypotractal processes to form quite well-develOped septa. In the Navarro forms the septa are not as greatly developed. The Navarro forms also differ from the Cenomanian forms in that the postcingu- lar processes are not as well—developed. The aculei of specimens observed here is very well developed and are recurved. 9, cf. asymmetricum is restricted to the Neyland- ville Formation in the Austin composite section, and may prove to be a marker species. Occurrence: Rare in Ney1andville Formation, Austin compos- ite section. Genus Bystematpphora Klement, 1960 Type gpecies: Systematophora areolata Klement, 1960. Upper Jurassic (Kimmeridgian); Germany. Systematpphora sp. 1 sp. nov. P1. 13, Figs. 8-10 P1. 14, Figs. 1-3 Diagnosis: Central body spherical, composed of two layers. Endophragm thicker than periphragm, the latter giving rise to the processes. Processes intratabular, annular, taeniate, 61 slender, solid. Processes, in some, entire to approximately the mid-point along their length and then becoming bifurcate. 'Process tips acuminate, bifid or trifid. Reflected tabula- tion 6 precingular, 5 postcingular, 2 posterior intercalary, 1 antapical. Periphragm finely verrucose. Archeopyle mar- gin not zig-zag, somewhat circular; re—entrant angle between fields moderate, shallow. Holotype: Pb 4505, slide 1, coord. 45.8 x 109.0. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 68 microns; length of processes 14 to 16 microns. Average dimensions of 4 Specimens: diameter of central body 68 to 74 microns; length of processes 12 to 17 microns. Remarks/Relationships: Entire specimens and those without an epithema are observed in the Navarro material. The forms here agree somewhat to B, areolata Klement in size and out- line of the archeopyle margin, but differ in having shorter and thinner processes. Occurrence: Abundant in Corsicana Formation; common in Kemp Formation, Austin composite section; common in Escon— dido Formation, Frio County, Texas. 62 Family Hystrichosphaeraceae Evitt Genus Bystrichosphaera O. Wetzel, 1933, emend. Davey and Williams in Davey et al., 1965 (p. 29) pType species: Hystrichopphaera (Xanthidium) ramosa (Ehren- berg), 1838. Upper Cretaceous (Senonian); Germany. Bystrichosphaera ramosa (Ehrenberg, 1838), emend. Davey and‘Williams in Davey et al., 1965 (p. 32) P1. 14, Figs. 7-11 1838. Bystrichosphaera ramosa (Ehrenberg) (a1 Xanthidium ramosum), pl. 1, fig. 14. Upper Cretaceous, Germany. Discussion: Navarro specimens referable to B, ramosa have the characteristics of the description of the species. Central body possesses zonal and sutural processes. Pro- cesses are solid, usually long and slender. Gonal processes, trifurcate, wall smooth. Dimensions: Range of 4 specimens: diameter of central body 46 to 52 microns; length of processes up to 16 microns. Remarkiselationship_: This species is recorded from the Cenomanian of Britain, Cookson and Hughes (1964). Davey et a1. (1966) state that it has been recorded as B, furcata from the Oxfordian by Deflandre (1938) and by Sarjeant (1960). Pleistocene occurrences have been recorded by Fries (1951) and Rossignol (1964). 63 Occurrences: Common in Corsicana and Kemp Formations, Austin composite section; rare in Escondido and Olmos Forma- tions, Frio County, Texas. Hystrichosphaera ramosa var. 1 var. nov. P1. 14, Figs. 9-11 Diagnosis: Hystrichosphaera ramosa var. l conforms to the emended diagnosis of B, ramosa by Davey and.Williams (1966), though is distinct from other Navarro specimens referable to the Species in possessing a distinctly punctate to reticulate wall. Processes solid, slender, trifurcate distally; cyst- like features extend entire length of processes; cysts more developed in some specimens than others. Holotype: Pb 4514, slide 1, coord. 30.8 x 87.0. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 43 microns; range of processes 7 to 10 microns. Average range of 4 Specimens: diameter of central body 40 to 48 microns; length of processes 6 to 10 microns. Remarks/Relationship_: H. ramosa var. 1 occurs in all For- mations of the Austin and Frio sections. It occurs in large numbers near the tOp of the Corsicana Formation and in the upper Kemp Formation, Austin composite section. It also occurs commonly near the top of the Escondido Formation, Frio County. The distinctly punctate to reticulate wall and cyst-like features of the processes makes this type easily identifiable. 64 Occurrence: Rare Neylandville Formation, abundant in Corsicana and Kemp Formations, Austin composite section; rare Olmos Formation, abundant Escondido Formation, Frio County. Hygtrichosphaera sp. 1 sp. nov. P1. 15, Figs. 7-9 Diagnosis: Test ellipsoidal, composed of thin endophragm and periphragm. Periphragm smooth to finely granular. Processes appear solid, are broad at the bases and taper towards the tips; distally processes closed, usually bifur- cate or trifurcate. Web-like membrane interconnects some adjacent processes near their bases. Girdle or sulcus not distinct. Archeopyle not observed. Holotype: Pb 4518, slide-l, coord. 34.2 x 104.8. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: length of test 46 microns; width of test 38 microns. Range of 3 specimens: length of test 38 to 52 microns; width of test 31 to 39 microns. Remarkiselationships: The web-like membrane interconnect- ing adjacent processes near their bases distinguish this species from others observed in the Navarro group. Occurrence: Common Corsicana Formation, Austin composite section. “tin .. '. 5k (I) [L51 65 Bystrichosphaera sp. 2 sp. nov. P1. 14, Figs. 4-6 Diagnosis: Test ellipsoidal. Wall thin, smooth to finely punctate. Processes thin, short bifurcate or trifurcate distally. Girdle and sulcus not clearly discernible. Archeopyle seldom identifiable. Holotype: Cp—l slide s—l, coord. 34.3 x 94.2. Kemp Forma- tion (Maestrichtian), Austin composite section. Dimensions: Holotype: length of test 41 microns; width of test 41 microns; length of processes up to 7 microns. Range of 4 specimens: length of test 40 to 46 microns; width of test 40 to 43 microns; length of processes, up to 10 microns. Remarkiselationships. This species is closely similar to the Navarro specimens referable to B, ramosa var. 1 in test outline and in possessing a punctate wall, though this species has a thinner wall and the punctations are not as coarse. Occurrence: Rare in Corsicana Formation; abundant in Kemp Formation, Austin composite section. Hystrichosphaera sp. P1. 15, Figs. 4-6a DiagnosiS: Test ellipsoidal. Wall moderately thick, smooth to finely punctate. Processes arise from low, thin sutures which reflect plate boundaries. Processes short, thin; those at juncture of fields usually trifurcate distally. Girdle clearly discernible. Archeopyle usually present. 66 Dimensions: Range of 2 specimens: length of test, 46 to 51 microns; width of test, 44 to 46 microns. Genus AchomOSphaera Evitt, 1963 Type species: B, (a1. Bystrichosphaeridium) ramulifera (Deflandre, 1937a), Upper Cretaceous; France. AchomOSphaera ramulifera (Deflandre), Evitt, 1963 1937. Achomopphaera (a1. Bystrichosphaeridium) ramulifera, (Deflandre, 1937), p. 74, pl. 15, figs. 5-6. Upper Creta- ceous; France. Discussion: The Navarro forms attributed to B, ramulifera do not differ appreciably from the type description. The wall surface in the Navarro forms is finely to coarsely granular, and the processes Split and unite near their tips forming a cyst-like structure. Dimensions: Range of 3 specimens: diameter of central body 35 to 46 microns; length of processes up to 16 microns. RemarksZRelationships: B, ramulifera is described by Deflandre (1937) from the Upper Cretaceous of France. The species is also recorded from the Ypresian of Belgium (Pastiels, 1948), the upper Oligocene-middle Miocene of Germany (Gerlach, 1961) and the upper Oligocene of Germany (Brosius, 1963) and from the London Clay, Eocene of Britain (Davey et a1, 1966). 67 Occurrence: Rare in Neylandville Formation; common in Corsicana Formation; rare in Kemp Formation; Austin compos- ite section; rare in Escondido and Olmos Formations, Frio County, Texas. Genus Cannosphaeropsis O. Wetzel 1932a Type species: Cannopphaeropsis utinensis O. Wetzel, 1933. Cretaceous; Baltic. Cannosphaeropsis cf. fenestrata Deflandre & . Cookson, 1955 P1. 15, Figs. 10-11 1965. Cannosphaeropsis fenestrata Deflandre & Cookson: p. 283, pl. 3, fig. 2, text-fig. 43. Upper Cretaceous (Senonian); Australia. Discussion: The Navarro forms referable to B, fenestrata compare fairly well to the specific description given by Deflandre & Cookson. The Navarro forms have smaller shells and the enveloping network is not perforated and is finer than in the type material. Specimens here compare more closely with the specimens of B, fenestrata illustrated by Cookson & Eisenack (1955), pl. VII, figs. 1-3. Dimensions: Range of 4 specimens: diameter of central body 31 to 46 microns. Remarks/Relationship_: B, cf. fenestrata does not occur in abundance in any samples, but when found is in an index form 68 of Zone A of the Austin composite section. Occurrence: Rare in Neylandville Formation, Austin compos- ite section. Family Areoligeraceae Evitt Genus Cyclonephelium Deflandre & Cookson, 1955, emend. Williams and Downie in Davey et al., 1966 (p. 223) Type species: gyclonephelium’cOmpactum Deflandre & Cookson, 1955. Lower to Upper Cretaceous; Australia. Cyclonephelium sp. 1 sp. nov. . P1. 16, Figs. l—3a Diagnosis: Central body nearly circular in outline, with indented base. Two small antapical convexities suggesting antapical horns, one of which is more prominent than the other. Circumferental area on dorsal surface with thin elongate processes which are interconnected distally, con- necting processes of adjacent plates. Ventral central area devoid of processes. Sulcal notch prominent, offset. Pro- cesses on dorsal central area. Postcingular fields of dorsal central area with annular process complex. Cingulum on dorsal surface delineated by processes. Processes rise from the periphragm and consist of annular or linear group— ings of processes which tend to indicate a regular distribu- tion. Archeopyle outlined by 6 precingular fields. Pro- cesses on precingular fields 2, 3 and 4 form annular 69 complexes; precingular field 6 always without processes; processes sometimes on field number 1. Processes solid taeniate, complexity united distally. The processes usually arise singly, proximately. Holotype: Pb 4501, slide l—A, coord. 38.3 x 107.0. Corsi- cana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 60 by 69 microns; length of processes 15 to 35 microns. Average dimensions of 8 specimens: diameter of central body 65 to 75 microns; length of processes 15 to 38 microns. Remarks/Relationships: B, sp. 1 appears to be quite similar to illustrations of B, exuberans, pl. V, figs. 11-12, given by Pastiels (1948) from the Eocene of Belgium, but the Navarro Specimens are much larger in Size than that species. Occurrence: Rare in Neylandville Formation; abundant in Corsicana Formation; common in Kemp Formation, Austin compos- ite section; common in Olmos and Escondido Formations, Frio County, Texas. Cyclonephelium sp. 2 Sp. nov. P1. 17, Figs. 2-6a P1. 18, Fig. l Diagnosis: Central body nearly circular in outline, with slightly indented:base; antapical convexities suggesting antapical horns, one more prominent than the other. Circum— ferential area of ventral surface with processes formed from 70 the periphragm. Processes elongate and complexly intercon- nected distally. Processes interconnected from adjacent plates. Central areas of dorsal and ventral surfaces free of processes. Subequal edges of precingular plates are indicated by the angulations of the archeopyle margin, resulting from 6 precingular fields. Precingular fields 3 and 6 never possessing processes; processes on precingular fields 1 and 5 intratabular; precingular fields 2 and 3 are larger than 1 and 6. Few stray processes are present on the periphery of the dorsal surface. Sulcal notch, prominent, offset. Holotype: JC-40, Slide 1, coord. 46.0 x 95.2. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body, 79 by 65 microns; length of processes 25 microns. Average range of 5 specimens; diameter of central body 75 to 80 microns; length of processes up to 31 microns. Remarks/Relationship_: chlonephelium sp. 1 occurs in abundance in some samples of the Corsicana Formation, Austin composite section. This species is somewhat similar to B, gpastielsi Deflandre & Cookson (1955) in outline, and process arrangement, but 9, sp. 1 is much larger in size than the type material of B, pastielsi. Occurrence: Common in Corsicana Formation; rare in Kemp Formation, Austin Texas composite section; common in Escon- dido Formation, Frio County, Texas. 71 gyclonephelium Sp. 3 Sp. nov. P1. 16, Figs. 4+7 P1. 17, Figs. l-la Diagnosis: Central body nearly circular in outline; apical region tapers to a small short protruberance. Circumferen- tial area of ventral surface with lace-like frill. Wall of central body finely punctate. Archeopyle margin showing 6 precingular fields. Holotype: Nav. ll, slide 1, coord. 43.3 x 104.0. Corsicana Formation (Maestrichtian), Quarry of Whitsell Brick Company, Corsicana, Texas. Dimensions: Holotype: diameter of central body 78 by 80 microns. Average range of 3 specimens: diameter of central body 72 to 80 microns. Remarks/Relationships: This species is somewhat similar to B, vitilare, Cookson (1965), from the Paleocene of Australia, in outline, and in possessing a perforated circumferential membrane. Though in B, sp. 3 the perforations are not as coarse as in.§, vitilare and do not appear to be the result of fusion of low, much-branched ridges. Occurrence: Rare in Corsicana Formation, Austin composite section. 72' Cyglonephelium cf. divaricatum Davey at al., 1966 P1. 20, Figs. 1-6 1966. Cyclonephelium divaricatum Davey et al., 1966; p. 223, pl. 25, fig. 1, text—fig. 60. Eocene; Britain. Discussion: Navarro specimens referable to B, divaricatum conform closely to the description given by Davey at al., 1966. The Navarro forms differ in that the surface of the central body is smooth, whereas the London Clay forms have a finely reticulate central body. Dimensions: Range of 5 specimens: diameter of central body 65 to 70 microns; length of processes up to 16 microns. Remarks/Relationships: gyclonephelium cf. divaricatum is recorded from the Eocene, London Clay Formation of Britain (Davey et al., 1966). This form appears to be restricted to the upper part of the Kemp Formation in the Austin composite section, and may be an indicator for that part of the Navarro. Occurrence: Common in Kemp Formation, Austin composite sec- tion. Genus Tenua Eisenack 1958b Type species: .2- hystrix Eisenack 1958b, p. 410, pl. 23, figs. 1—4, text-fig. 10. Aptian, Germany. 73 T2223 sp. 1 sp. nov. P1. 18, Figs. 4-5 Diagnosis: Test subspherical in outline, one side of antapex attenuated into a small, rounded protruberance. Processes intratabular; processes densely cover test; pro- cesses solid, tabular, slightly expanded proximately dis- tally, and with blunt apices. Precingular fields 3, 4, 5 larger than 1, 2 and 6. Cingulum helicoidal. Holotype: Pb 4632, slide s-2, coord. 39.3 x 104.2. Neyland- ville Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: length (excluding epithema) 78 microns; width 93 microns. Range of 3 specimens: length 75 to 80 microns; width 85 to 94 microns. Remarks/Relationships: The tabular processes distinguish this species from others described in the genus. Occurrence: Rare in Neylandville Formation, Austin compos- ite section. Tenua cf. hystrix Eisenack, 1958 'P1. 18, F193. 2-3 1958. Tenua hystrix Eisenack, 1958, p. 410, pl. 23, figs. 1-4. Aptian; Germany Discussion: The writer has not seen the holotype of this species, but the illustration and description given by Eisenack appear comparable to the Navarro forms. The test is covered with densely distributed short rod—like 74 projections. In specimens observed here, boundaries between plates are not marked and thus the tabulation is not indi- cated. Dimensions: Range of 2 specimens: length 82—90 microns; width 77-84 microns. Remarks/Relationships: Tenua Bystrix is described by Eisenack (1958b) from the Lower Cretaceous (Aptian) deposits from Germany. Only a few specimens of this Species were observed from the Neylandville Formation and it was not recognized elsewhere in the Navarro Group. Occurrence: Rare in Neylandville Formation, Austin compos- ite section. Genus Areoligera Lejeune-Carpentier, 1938 emend. Williams and Downie in' Davey et a1, 1966 (p. 227-228) Type species: B, senonensis Lejeune-Carpentier, 1938b. Upper Cretaceous (Senonian), Belgium. Areoligera senonensis Lejeune— Carpentier, 1938 P1. 19, Figs. 1-3 1938. Areoligera senonensis Lejeune-Carpentier: Bl64—6, text-figs. 1-3. Upper Cretaceous; Belgium. Discussion: Excellently preserved specimens of B, senonensis are observed from the Navarro material. Processes on dorsal surface reflect 3 precingular fields bearing soleate 75 processes; 3 postcingular fields, one soleate and two annular. One antapical field bearing annular processes. Antapex with two protruberences, the largest lying beneath the sulcal notch. Dimensions: Range of 3 specimens: diameter of central body from 62 to 70 microns to 65 to 72 microns. RemarksZRelationships: B, senonensis is recorded from the Senonian of Belgium, Lejeune—Carpentier (1938), the Paleocene of South Dakota, Stanley (1965), the Eocene of Britain, Davey et a1. (1966), and the Maestrichtian of New Jersey, Evitt (1961). Occurrence: Abundant in Corsicana Formation; common in Kemp Formation; Austin composite section; rare in Escondido and Olmos Formations, Frio County, Texas. Areoligera sp. 1 sp. nov. P1. 19, Figs. 4-9 Diagnosis: Central body flat with subcircular outline. The six precingular and four postcingular fields bearing soleate processes which rise from the periphragm. Processes short, usually not united distally; erect, acuminate, bifid or trifid distally. Length of processes rarely exceeding one- third the diameter of central body. Antapex of central body usually with a single small protruberance. Holotype: Pb 4505, Slide 1, coord. 28.7 x 102.2. Corsicana Formation (Maestrichtian), Austin composite section. 76 Dimensions: Holotype: length of central body 60 microns; width of central body 57 microns; length of processes up to 14 microns. Range of 5 specimens: length of central body 60 to 65 microns; width of central body 55 to 65 microns; length of processes 8 to 15 microns. Remarks/Relationships: Areoligera sp. 1 sp. nov. is some- what similar to Areoligera senonensis in tabulation, though in this species the processes are much more reduced in size. Occurrence: Abundant in Corsicana Formation, Austin compos- ite section; rare in Olmos Formation, Frio County, Texas. Areoligera sp. 2 sp. nov. P1. 18, Figs. 6-9 Diagnosis: Central body subspherical in outline. Wall finely punctate. Processes arise singly or in pairs; cir- cumferential processes are on both dorsal and ventral sur- faces; processes on dorsal surface appear to be linear. Precingular plate 1 with linear processes; 3 with soleate processes. Holotype: Pb. 4504, Slide 2, coord. 44.0 x 86.5. Corsi- cana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: length of central body 68 microns; width 68 microns. Range of 5 Specimens: diameter of cen- tral body 62 to 65 microns. Remarks/Relationships: This species appears to be closest to Areoligera coronata (O. Wetzel), but the author has not 77 examined the holotype to make a more precise identification. Occurrence: Abundant in Corsicana Formation; common in Kemp Formation; Austin composite section. Genus Forma B Gen. nov. Diagnosis: Dorso-ventrally flattened cysts. Central body oval in outline, the apex with a slight prominence suggest— ing an apical horn; antapical outline with two convexities with a depression between suggesting antapical horns. Cir- cumferential areas of dorsal and ventral surfaces with sur- rounding membrane. Ventral and dorsal central areas not covered with membrane. Archeopyle apical. Sulcal notch offset. Type species: Forma B sp. 1 sp. nov. Corsicana Formation (Maestrichtian) Austin composite section. Remarks/Relationships: This genus is somewhat similar to Tenua, _yclonephelium and.Areongera in that they all are dorso-ventrally flattened, have an apical archeopyle, and an Offset sulcal notch. Forma B sp. 1 Gen. et sp. nov. P1. 20, Figs. 7-8b Diagnosis: Central body subspherical. Apex tapering to a slight prominence; antapical outline with two convexities. Surrounding membrane attached to circumferential areas of dorsal and ventral surfaces. Membrane attached to ventral surface with a few fine stray processes. 78 Holotype: Pb 4509, slide 3, coord. 36.8 x 106.2. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: diameter of central body 63 by 52 microns. Average range of 5 specimens: diameter of central body 60 to 65 microns by 50 to 55 microns. Remarka/Relationships: This species occurs abundantly in the upper portion of the Corsicana Formation and from sam- ples from the Olmos Formation, and is used as a. horizon marker species. Occurrence: Abundant in Corsicana Formation, Austin compos- ite section, common in Escondido Formation, Frio County, Texas. Family Hystrichodiniaceae Deflandre Genus Heliodinium Alberti, 1961 emend. Sarjeant in Davey et al., 1966 Typa species: Heliodinium voigti Alberti: p. 33, pl. 8, figs. 1-5. Lower Cretaceous (Barremian); Germany. Heliodinium cf. voigti Alberti, 1961, emend. Sarjeant in Davey et al., 1966 (p. 142) 1961. Heliodinium voigti Alberti: p. 33, pl. 8, figs. 1-5. Lower Cretaceous; Germany. 1966. B, voigti (Alberti, 1961) emend. Sarjeant in Davey et al., 1966: p. 142-144, pl. 16, fig. 2, text—fig. 36. 79 Discussion: Specimens referable to B, voigti from the Navarro material are rare and poorly preserved, and dis- torted in most instances. The processes are dagger-like and flexible; distal ends are simple, usually acuminate. The surface of most specimens appears smooth. Tabulation was not determined. Dimensions: Range of 3 specimens: length of central body 40 to 60 microns; width of central body 35 to 46 microns; length of processes up to 22 microns. Remarks/Relationships: B, voigti is originally described from the Lower Cretaceous (Upper Barremian) of Germany by Alberti (1961). Davey et a1. (1966) report it from the Upper Cretaceous (basal Cenomanian) of Britain. Occurrence: Rare in the Neylandville Formation, Austin composite section. Family Gymnodiniaceae Bergh Genus Bymnodinium Stein, 1878 emend. Kofoid and Swezy, 1921 Type Species: (based on extant type species.) Discussion: Non-tabulate ellipsoidal to biconical fossil tests without processes; with more or less equatorial Cingulum; with sulcus mostly in the hypothecal portion; presently assigned to the genus Bymnodinium. These features conform to the circumscribed limits of the modern genus 80 ,Gymnodinium. Whether the fossil forms of the genus repre- sent cysts or the free-living stage is not yet certain. Evitt, personal communication has proposed a new genus Dinogymnium for typical fossil "Gymnodinium." The features distinguishing Dinogymnium from modern Gymnodinium are a chemically resistant wall, small apical archeopyle, and wall partly or completely penetrated by minute canals. These features, except for the wall canals, indicate a cyst inter- pretation of fossil Gymnodinium, and possibly indicate a mode of encystment different than in other fossil dinoflagel- lates. Gymnodinium nelsonense-Cookson, 1956 P1. 21, Figs. lO—l3a P1. 22, Figs. 122 1956. Gymnodinium nelsonense Cookson: p. 183-4, pl. 1, figs. 8-11. Upper Cretaceous; Australia. Discussion: The Navarro forms attributed to B. nelsonense agree to the type description of the species. An opening at the apex of the epitract, which is here considered to be analgous to an archeopyle, is observed in nearly all speci- mens examined. Dimensions: Range of 5 Specimens: length of test 68 to 75 microns; width of test 30 to 35 microns. Remarks/Relationships: In several samples of the Neyland- ville Formation B. nelsonense occurs in great abundance, and 81 dominates the assemblage. This large occurrence of individ- uals may have stratigraphic significance in local correla- tions. B, nelsonense is reported from the Cannonball Marine Member, Paleocene, from South Dakota by Stanley (1966). Cookson and Eisenack (1957) state that the range of the species is from Campanion to Lower Maestrichtian in Austra- lia. Occurrence: Abundant in Neylandville Formation; rare in Corsicana Formation, Austin composite section; rare in Olmos Formation, Frio County, Texas. Gymnodinium westralium Cookson and Eisenack, 1958 P1. 22, Figs. 3-6 1958. Gymnodinium westralium Cookson and Eisenack, pp. 25- 26, pl. 1, fig. 9. Upper Cretaceous; Australia. Discussion: Navarro specimens of gymnodinium westralium possess a thin wall which is subject to distortions and folding. The girdle is well-defined by a central deep inden- tation. This species is somewhat Similar to Gymnodinium hetercostatum Deflandre, in shape and size, though B, westralium appears to have more deeply incised furrows than B, heterocostatum. Dimensions: Range of 5 Specimens: length of test 45 to 58 microns; diameter of test 22 to 31 microns. 82 Remarks/Relationships: B, westralium is previously recorded from the Campanian and Lower Maestrichtian of Australia and also the Senonian and.Cenomanian to Lower Turonian of Australia. Occurrence: Common in Kemp Formation, Austin composite section; common in Escondido Formation, Frio County, Texas. Bymnodiniumidigitus Deflandre, 1935 P1. 22, Figs. 7-11 1935. Bymnodinium digitus Deflandre: p. 225, text-figs. 7-8. Upper Cretaceous; France. Discussion: The Navarro forms assigned to B. digitus com— pare closely with the specific description of the species given by Deflandre, though the specimens here have a more broadly rounded antapex and stronger development of longi— tudinal folds. The wall is finely granular and is pene- trated by minute canals which tend to be arranged longitudi- nally. In end view the Navarro specimens are ventrally- dorsally plano-convex. Dimensions: Range of 10 specimens: length of test 58 to 62 microns; width of test 18 to 22 microns. Remarka/Relationsths: An archeopyle or apical opening is observed in many of the Navarro specimens. In some samples the species occurs in great abundance or in clusters, and tends to dominate the assemblage. Whether this abundant 83 occurrence represents fossil dinoflagellate "blooms" is not certain. Occurrence: Abundant in Neylandville Formation; rare in Corsicana Formation, Austin composite section. BymnOdinium sp. 1 sp. nov. P1. 21, Figs. 1—4 Diagnosis: Test biconical. Hypotract blunt, broadly rounded at apex; epitract more narrowly rounded. Hypotract with short, narrow, longitudinal sulcus; wall not folded. Epitract with longitudinal folds. Wall punctate, Cingulum narrow, well defined; divides test into approximately two equal halves. Archeopyle small. Holotype: Jc-7, slide 2-A, coord. 43.4 x 104.5. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: length of test 34 microns; width of test 25 microns. Average dimensions of 8 specimens: length of test 30 to 35 microns; width of test 25 to 28 microns. Remarks/Relationships: This species is similar to B. cretaceum in general outline and size, but differs in having longitudinal folds on the epitract.’ Also in this species the hypotract apex is more broadly rounded than in B. cretaceum. A small opening at the apex of the epitract is suggested as being analogous to an archeopyle. Occurrence: Abundant in Corsicana Formation, Austin compos- ite section; common in Escondido Formation, Frio County, Texas. 84 Gymnodinium Sp. 2 sp. nov. P1. 21, Figs. 6—9 Diagnosis: Test fusiform, consisting of a Single wall. Cingulum distinct, narrow, deeply indented, dividing the test into approximately equal halves. Test eXpanded in mid- area. Epitract and hypotract with crenulated longitudinal folds more or less equally developed on both halves. Test wall with fine granules which extend along a linear trend to the apices. Wall penetrated with minute canals which tend to be most obvious on the epithema and Cingulum. Archeopyle relatively large. Holotype: Jc-7, slide 3-B, coord. 30.8 x 93.2. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: length of test 88 microns; width of test 58 microns. Average dimensions of 4 specimens: length of test 85 to 90 microns; width of test 55 to 60 microns. Remarks/Relationships: All of the Navarro Specimens of this species observed possess an Opening at the apex of the epitract analagous to an archeopyle. The epithema is attached in practically all specimens. This Species is close to Bymnodinium westralium and.B, heterocostatum in outline, possessing longitudinal folds and having minute. wall canals as in B, westralium, but differs from both of these species in being much larger in Size. Occurrence: Common in Corsicana Formation, Austin compos- ite section. 85 Bymnodinium sp. 3 Sp. nov. P1. 22, Figs. 12-14 Diagnosis: Test elongate; epitract and hypotract approx- imately equal in length. Antapex bilobed. Wall covered with fine granules which tend to be arranged longitudinally, and penetrated with minute canals. Epitract with longitudi- nal folds; hypotract with reduced number of folds or none at all. Cingulum narrow, well-defined. Holopype: Pb 4675, slide 1, coord. 37.4 x 84.3. Neyland- ville Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: length of test 60 microns; width of test 22 microns. Range of 3 specimens: length of test 58 .to 65 microns; width of test 22 to 26 microns. RemarkaZRelationships: Gymnodinium Sp. 3 is distinct from all previously described species of fossil Bymnodinium in the possession of a bilobed antapex. The bilobed character in this Species is more developed in some specimens than in others, but is always identifiable in the species. B, sp. 3 is similar to Navarro specimens of Gymnodinium digitus in elongate outline, minute wall canals, granular test, and longitudinal folds, but is easily distinguished by its bilobed antapex. B, Sp. 3 is found in stratigraphically lower samples than B, digitus, and whether B, digitus is an evolutionary develOpment or environmental development from B, sp. 3 is not known. It is thought that B, sp. 3 will prove to be of stratigraphic value with further work. No 86 archeopyle has been observed in the examined Specimens. Examples of modern Bymnodinium which possess bilobed anta- pical ends are: B, sulcatum, B, mirabile, B, incisum and B, wilczeki. Occurrence: Rare in Neylandville Formation, Austin compos- ite section. Gymnodinium sp. 4 Sp. nov. P1. 23, Figs. 1-2 Diagnosis: Test elongate, epitract and hypotract broadly rounded. Wall smooth to finely striate. Cingulum broad, poorly defined. Holotype: Pb 4675, slide 1, coord. 34.0 x 83.3. Neyland- ville Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: length of test 60 microns, width of test 30 microns. Average range of 3 specimens: length of test 55 to 62 microns; width of test 27 to 30 microns. Remarks/Relationship_: the broadly rounded apices and relatively simple morphologic features make this species easily recognizable. Occurrence: Rare in Neylandville Formation, Austin compos- ite section. 87 Gymnodinium sp. P1, 21, Fig. 5 Discussion: B, sp. is represented by one specimen from the Corsicana Formation of the Austin composite section. It is similar in shape and size to B, sp. 1 sp. nov., but differs in possessing rather sinuous longitudinal folds on both the epitract and hypotract. Dimensions: Length 35 microns; width 27 microns. Occurrence: Rare in Kemp Formation, Austin composite section. Genus DicOnodinium Eisenack and Cookson, 1960 AType species: D. (a1 PalaeohyStrichoPhora) multispinum (Deflandre and Cookson, 1955), Senonian; Western Australia. 'Diconodinium sp. 1 sp. nov. P1. 23, Figs. 3-4 Diagnosis: Test biconical, Cingulum approximately equato- rial. Test consists of a Single wall; wall very thin, covered with fine granules. Antapex angular truncate, one side prolonged into Short tapered point. Cingulum incised, probably heliocoid. Hologypa: Pb 4508, slide 3, coord. 28.3 x 90.8. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: length of test 40 microns; width of test 26 microns. Average range of 3 specimens: length of test 38 to 40 microns; width of test 24 to 27 microns. 88 Remarks/Relationships: Diconodinium sp. 1 is readily dis- tinguished from other species of the genus by its small size and finely granular wall. Occurrence: Abundant in Corsicana Formation; common in Kemp Formation, Austin composite section; common in Escondido Formation, Frio County, Texas. Family Gonyaulacaceae Lindemann Genus Gonyau1ax Diesing Type species: (Modern genus and type species.) Gonyaulax.sp. 1 sp. nov. Pl. 23,.Figs. 5-8 Diagnosis: Test ellipsoidal, with short apical horn. No indication of antapical horns. Capsule ellipsoidal, in close contact with outer wall. Reflected plate boundaries indicated by low distinct ridges. Cingulum narrow, well— defined, strongly spiral. Wall smooth or finely granular. Holotype: Pb 4509, slide s-l, coord. 49.0 x 93.7. Corsi- cana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: length of test 93 microns; width of test 87 microns. Range of 5 specimens: length of test 90 to 95 microns; width of test 82 to 88 microns. Remarks/Relationships: This species occurs commonly through- out the Navarro Group in the Austin and Frio sections. Its most abundant occurrence is in the Corsicana Formation, in 89 the Austin composite section. This species also occurs in the Red Bank Formation of New Jersey. Occurrence: Common in Neylandville Formation; abundant in Corsicana Formation; common in Kemp Formation, Austin compos- ite section; common in Olmos and Escondido Formations, Frio County, Texas. Family Pseudoceratiaceae Eisenack Genus Odontochitina Deflandre, 1935 Type apecies: .B. (a1. Ceratium) operculata (O. Wetzel, 1932) Deflandre and Cookson, 1955. Upper Cretaceous; Baltic. Discussion: The emendation of this genus would be in order, though the author has not examined sufficient material for an emendation at the present time. Specimens referable to the genus Odontochitina should include those forms with globular tests, possessing three horns. One horn is apical and another antapical; a third horn is postcingular (Evitt, personal communication), rising from the test from an area just below the equator. Apical rupture divides the test into two unequal parts. Margin of archeopyle with clefts suggesting field margins, but no other indication of tabula— tion. Cingulum not defined. Capsule close to test wall, except in areas of horns. 90 Odontochitina striatpperforata ..cookson and Eisenack, 1962 ,Pl.,24,1Figs.~7-8 1962. Odontochitina striatoperforata Cookson & Eisenack: p. 490, pl. 3, fig. 16. Upper Albian to Cenomanian; Australia. Dimensions: Range of 3 specimens: length of central body 38 to 50 microns; width of central body 42 to 60 microns; length of horns 75 to 82 microns. Remarks/Relationships: Several specimens referable to this species have been found, though none of them with epithema attached. The Navarro forms possess the perforated horns as described by Cookson and Eisenack, but the linear striations on the horns are more faint in the Navarro specimens. B, striatoperforata is restricted to the Neylandville Formation in the Austin composite section; therefore its presence in a sample may be stratigraphically important. .9. striatoper- forata is reported from the Albian and Cenomanian of Austra- lia by Cookson and Eisenack (1962) and from the Upper Cre- taceous of Graham Island, Arctic Canada. Evitt (1961, pl. 6, figs. 15, 16) illustrates a similar form from the Senonian of West Pakistan. Occurrence: Rare in Neylandville Formation, Austin compos- ite section. ‘ 91 Genus Forma C..Gen. nov. Diagnosis: Chorate cysts. Test usually ellipsoidal and possessing two different types of processes. Three large processes, one apical and one antapical; a third process is postcingular. Several smaller processes reflect the main plates of the test. Archeopyle apical; margins irregular or zig-zag. Large process Open or closed distally; small pro- cesses closed distally. Type Species: Forma C sp. 1 sp. nov. Corsicana Formation (Maestrichtian) Austin composite section. Remarks/Relationships: Evitt (1961, pl. 6. fig. 9) illus- trates this genus as Forma H. He states its relationship to Odontochitina in possessing a cyst within a cyst; having apical, antapical, and postcingular horn (personal communica- tion); and also its relationship with Bystrichosphaeridium in having the ends of the processes flared. Forma C Sp. 1 Gen. et sp. nov. Diagnosis: Test ellipsoidal, periphragm smooth, giving rise to the processes. Capsule ellipsoidal, penetrated by minute canals and in close contact with periphragm except in areas of apical and antapical horns. Smaller processes reflect field boundaries and are solid, closed distally and possess Slightly flared tips. Apical processes Open distally and with denticulate margin. 92 Holotype: Pb 4675, slide 1, coord. 40.8 x 88.0. INeyland- ville Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: length of central body 69 microns; width of central body 58 microns. Remarka/Relationships: Forma C sp. 1 is restricted to the Neylandville Formation in the Austin composite section and is not observed in the Frio County section. In some samples this species is relatively abundant and their unusual mor- phology makes them readily identifable. Only a few complete specimens were observed; the majority of the forms are found with the epithema detached. The epithema is observed com- monly in samples containing the main body. Occurrence: Common in Neylandville Formation, Austin compos- ite section. Family Deflandreaceae Eisenack Genus Deflandrea Eisenack 1938, emend. Williams and Downie in Davey at al., 1966 (p. 231) Type species: Deflandrea_pnosphoritica Eisenack, 1938. Oligocene; East Prussia. Deflandrea acuminata.CoOkson & Eisenack, 1958 1958. Deflandrea acuminata Cookson & Eisenack: p. 27, pl. 4, figs. 5-8. Cenomanian - Lower Turonian; Australia. 93 Dimensigns: Range of 4 specimens: length of test 62 to 77 microns; width of test 38 to 46 microns; length of capsule 39 to 51 microns; width of capsule 31 to 38 microns. Remarga/Relationships: This species has been previously recorded from the Cenonmanian to lower Turonian of western Australia. It seems to be restricted to the Neylandville Formation, Austin composite section. Occurrence: Rare in Neylandville Formation, Austin composite section. Deflandrea cooksoni Alberti, 1959 P1. 25' Figs. 8-9, 12 1959. Deflandrea cooksoni Alberti: p. 97, pl. 9, figs. l-6. Upper Cretaceous; Germany. Dimensions: Average range of 5 specimens: overall length of test 78 to 84 microns; overall width of test 46 to 53 microns. RemarksZRelationships: The wall of the Navarro forms of this species are medium thick, and probably brittle, as many specimens are subject to fracturing. There appears to be much morphologic variation among the Navarro specimens, though all probably belong to this species. Alberti (1959) described B. cooksoni form the Senonian of Germany, and it is known to occur in the Red Bank Formation (Maestrichtian), of New Jersey. 94 Occurrence: Common in the Corsicana Formation, Austin composite section; rare in Escondido Formation, Frio County, Texas. Deflandrea microgranulataStanley, 1965 1965. Deflandrea micrognanulata Stanley: p. 219, pl. 19, figs. 4—6, Paleocene; South Dakota. Dimensions: Average range of 4 Specimens: overall length 51 to 60 microns; overall width 41 to 48 microns. Remarks/Relationships: Deflandrea micrognanulata is reported by Stanley (1965) from the Paleocene of South Dakota. Occurrence: Common in Corsicana Formation; common in Kemp Formation, Austin composite section; common in Escondido Formation, Frio County, Texas. Deflandrea magnifica Stanley, 1965 .P1. 29, Fig. 7 P1. 30, Figs. 1-4 1965. Deflandrea magnifica Stanley: p. 218, pl. 20, figs. 1-6. Paleocene; South Dakota. Discussion: Navarro Specimens referable to B, magnifica closely conform to the description given by Stanley (1965). Dimensions: Range of 6 Specimens: overall length 65 to 93 microns; overall width 53 to 92 microns. 95 Remarks/Relationship_: This species is previously reported from the Paleocene of South Dakota by Stanley (1965). Spec- imens of B, magnifica from the Corsicana Formation in the Austin composite section are almost always larger in Size than those observed from the Frio County, Texas subsurface section. Occurrence: Common in Corsicana Formation; abundant in Kemp Formation, Austin composite section; abundant in Escondido Formation, Frio County, Texas. Deflandrea pannucea Stanley, 1965 P1. 28, Figs. 3-4 P1. 29, Figs. 1-3 1965. Deflandrea pannucea Stanley: p. 220, pl. 22, figs. 1-4, 8-10. Paleocene; South Dakota. Discussion: The Navarro specimens of Deflandrea pannucea conform to the circumscribed limits of the specific descrip- tion given by Stanley (1965), though the Navarro forms are larger in size. Dimensions: Range of 8 specimens: outer shell length 120 to 146 microns; width 62 to 95 microns; capsule length 53 to 77 microns; width 60 to 93 microns; length of apical horn 22 to 38 microns. Remarks/Relationships: Deflandrea pannucea has been pre- viously described from the Paleocene of South Dakota by Stanley (1965). The species is easily recognized by its 96 longitudinally folded periphragm. Specimens of this Species studied from the Neylandville Formation of the Austin compos- ite section are consistently larger in size than those observed from the Corsicana Formation. The Neylandville Specimens also have less attenuated horns. Occurrence: Common in Neylandville Formation; common in Kemp Formation, Austin composite section; common in Olmos and Escondido formations, Frio County, Texas. Deflandrea micracantha, Cookson & Eisenack, 1960 P1. 25, Figs..lO—ll 1960. Cookson and Eisenack: p. 3, pl. 1, fig. 9. Upper Cretaceous; Australia. Discussion: Specimens referable to B, micracantha from the Navarro material closely conform to the description given by Cookson & Eisenack though the Navarro forms are somewhat smaller in Size. Dimensions: Range of 2 Specimens: overall length 82 to 85 microns; overall width 53 to 60 microns. Remarks/Relationship_: B, micracantha is described from the Campanian of Australia. The wall of the Navarro form is relatively thick and subject to fracturing. Occurrence: Rare in Neylandville Formation, Austin composite section. 97 ? Deflandrea sp. 1 sp. nov. P1. 30, Figs. 7-8a Diagnosis: Test pentagonal in outline, consisting of one wall. Wall finely granular. Apical horn short, narrowly rounded at apex. Antapical horns non-divergent, short, narrowly rounded at apices, and sometimes poorly developed. Cingulum indicated by transverse folding of the wall at mid- region. Epithema consisting of three trapezodial fields. Holotype: Pb 4501, slide 4—A, coord. 28.2 x 90.2. Corsi— cana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: length of test 69 microns; width of test 53 microns. Average range of 4 specimens: length 69 to 74 microns; width 51 to 60 microns. Remarks/Relationship_: This Species is placed questionably in the genus Deflandrea because of the absence of a capsule, though possessing all the other characteristics of the genus. The species is common in the Corsicana and Kemp formations, and in all instances, the specimens observed have only one wall. Occurrence: Common in Corsicana Formation; common in Kemp Formation, Austin composite section; rare in Escondido Formation, Frio County, Texas. 98 Deflandrea sp. 2 Sp. nov. P1. 26, Figs. 1-8 Diagnosis: Test pentagonal in outline. Periphragm covered with tiny spinules which Show a tendency to be locally aligned in indistinct rows, probably reflecting field bound- aries. Capsule large, smooth, fills enclosing test except in area of apical and antapical horns. Cingulum sinistral, well—defined; margins with tiny spinules. Archeopyle large, approximately hexagonal in outline, with rounded corners. Holotype: Pb. 4504, Slide G-l, coord. 35.3 x 104.2. Corsi- cana Formation'(Maestrichtian), Austin composite section. Dimensions: Holotype: outer shell length 115 microns, width 69 microns, capsule length 69 microns, width 68 microns; length of apical horn 30 microns. Range of 5 specimens: outer shell length 63 to 115 microns; width 53 to 75 microns. Remarks/Relationships: Deflandrea denticulata Alberti (1959) from the Paleocene-Lower Eocene of Germany is quite close to this Species. Deflandrea sp. 2 differs from the German material in possessing much smaller spines. Occurrence: Common in Corsicana Formation; rare in Kemp Formation, Austin composite section. Deflandrea sp. 3 sp. nov. P1. 29, Figs. 4-6 Diagnosis: Test pentagonal in outline, composed of smooth endophragm and periphragm. Capsule large, ovoidal in out- line, in close contact with outer wall except in areas of 99 apical and antapical horns. Cingulum helicoidal; margin beaded. Archeopyle rhomboidal. Holotype: JC-40, slide 4, coord. 46.7 x 95.5. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: outer Shell length 124 microns, width 78 microns; capsule length 69 microns, width 70 microns. Range of 4 specimens: outer Shell length 115 to 125 microns, width 67 to 70 microns; capsule length 68 to 70 microns, width 67 to 70 microns; length of apical horn up to 31 microns. Remarka/Relationships: Deflandrea sp. 3 is close to B. obliguipes, Deflandre & Cookson (1955) in outline and possessing smooth walls, but this Species differs in having the margins of the Cingulum ornamented with beads, not hav- ing a punctate wall, and possessing a rhomboidal rather than a triangular archeopyle. The antapical horns in this species are also less divergent than in B, obliqnipes. .B. Sp. 3 is easily recognized by its smooth wall and rhomboidal archeopyle. Occurrence: Common in Corsicana Formation, Austin composite section. Deflandrea sp. 4 sp. nov. pl. 28, Figs. 1-2 Diagnosis: Test fusiform, expanded at mid-area. Endophragm in close contact with periphragm except in areas of apical 100 and antapical horns. Apical and antapical horns atenuated into relatively short tapered points. Periphragm coarsely granular. Archeopyle large, triangular; not always distinct. Holotype: Pb 4677, slide 1, coord. 47.5 x 96.3. Neyland— ville Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: overall length 144 microns, overall width 78 microns; length of central body 100 microns; width of central body 78 microns. Range of 5 specimens: overall length 140 to 170 microns; overall width 74 to 78 microns; length of central body 78 to 115 microns; width 72 to 78 microns. RemarksZRelationship_: Deflandrea sp. 4 is distinct from other described species of Deflandrea in outline and orna- mentation of periphragm. In some specimens the archeopyle is difficult to distinguish if the archeopyle of the capsule is closely associated with the outer wall. Deflandrea sp. 4 is restricted to the Neylandville Formation and is a marker Species for zone A. Occurrence: Common in Neylandville Formation, Austin compos- ite section. Deflandrea sp. 5 Sp. nov. P10 27’ Figs. 3'4 Diagnosis: Test subquadrate, composed of thin, smooth endophragm and periphragm. Capsule in close contact with outer wall, except in areas of apical and antapical horn. 101 Apical horn Short, with blunt tip. Antapical area attenu- ated into small, pointed protruberance. ArcheOpyle tri- angular. Holotypa: Pb. 4673, slide 2, coord. 42.8 x 106.2. Neyland- ville Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: overall length 63 microns; overall width 36 microns. Range of 3 specimens; overall length 51 to 63 microns; overall width 34 to 40 microns. Remarkiselationshipn: The outer and inner walls of this species are very thin and best studied with phase contrast microscopy. Its small size and distinctive outline dis— tinguish it from other species of the genus. Occurrence: Common in Neylandville Formation, Austin compos- ite section. Deflandrea sp. 6 sp. nov. P1. 27, Figs. 5-7 Diagnosis: Test subquadrate in outline; composed of smooth endophragm and periphragm which bears small tubercles that are somewhat aligned in a regular fashion. Tubercles are most dense at the mid-area or capsular region. Apex tapers to Short blunt point. Antapex angular, truncate on Side prolonged into a short horn. Archeopyle broadly rounded at anterior. Epithema attached posteriorly. Holotype: Pb. 4632, slide 3 coord. 38.0 x 100.2. Neyland- ville Formation (Maestrichtian), Austin composite section. 102 Dimensions: Holotype: overall length 72 microns; overall width 47 microns; length of central body 38 microns; width 46 microns. Range of 4 specimens: overall length 54 to 73 microns; overall width 46 to 48 microns. RemarksZRelationsthS: Deflandrea sp. 6 is similar to Deflandrea balmei in general outline and tubercular ornamen- tation. This species differs in shape in archeopyle. B, sp. 6 is restricted to the Neylandville Formation of the Austin composite section and should prove to be stratigraphically important. Occurrence: Common in Neylandville Formation, Austin com- posite section. Genus Svalbardella Manum, 1960 Type species: Svalbardella cooksoniae Manum, 1960. Lower Tertiary; Spitsbergen. Svalbardella cf. lidiae (Gorka, 1963) P1. 31, Fig. l 1963. Liofusa lidiae Gorka: p. 37, pl. 5, fig. 6. Maestrichtian; Poland. Discussion: Specimens referable to B. lidiae in the Navarro appear quite close to Leiofusa lidiae Gorka (1963) from the Maestrichtian of Poland, though in the description of that species it is stated that there is no internal capsule. The 103 illustrated figure appears to indicate an internal capsule which is attenuated into the horns. Therefore,.it would be best to assign this species to Svalbardella. The endophragm and periphragm of the Navarro specimens are smooth. The archeopyle was not observed in any of the specimens examined, and the internal capsule does not extend into the horns as is indicated in B, lidiae. The horns of the Navarro mate- rial are attenuated into long tapered points, and the antap- ical horn is in some bifurcate. Dimensions: Range of 5 specimens: overall length 160 to 187 microns; overall width 45 to 53 microns. Remarks/Relationships: Svalbardella lidiae ranges through- out the Navarro group but it is abundant in the Kemp and Escondido Formations. This species was originally described from the Maestrichtian of Poland, Gorka (1963). Occurrence: Common in Neylandville and Corsicana Formations; abundant in Kemp Formation, Austin composite section; abundant in Escondido Formation; rare in Olmos Formation, Frio County, Texas. Family Apteodiniaceae Eisenack Genus Apteodinium Eisenack, 1958 Typaflapecies: Bpteodinium gganulatum Eisenack, 1958. Aptian; Germany. 104: Appeodinium Sp. 1 Sp. nov. P1. 30, Figs. 5-6 Diagnosis: Test oval in outline, composed of smooth endo- phragm and finely granular periphragm. Epitract terminated by short blunt horn; hypotract apex attenuated into two Short horns; Cingulum distinct; dextal. Archeopyle polygonal. Capsule in close contact with outer wall. Holotype: Pb. 4506, slide 3, coord. 46.5 x 87.3. Corsicana Formation (Maestrichtian), Austin composite section. Dimensions: Holotype: overall length 75 microns; overall width 58 microns. Range of 3 specimens: overall length 70 to 78 microns; overall width 55 to 60 microns. RemarkiselationShips: Bpteodinium Sp. 1 is similar to B, conjunctum Eisenack & Cookson (1960) in outline and in pos- Sessing a short apical horn, but it differs from that spe- cies in having a central body and a helicoid Cingulum. Occurrence: Common in Corsicana Formation, Austin compos- ite section. 105 DINOFLAGELLATES Of UNCERTAIN AFFINITY Genus Palaeohystrichophora Deflandre, 1934 emend. Deflandre and Cookson: 1955 Type npecies: Palaeohystrichophora infusorioides Deflandre, 1934. Cretaceous, France. Palaeohystrichophora inquorioides Deflandre, 1934 P1. 31,.Fig. 4 1934. Palaeonystrichophora infusorioides Deflandre: p. 967, fig. 8. Cretaceous; France. Discussion: Navarro specimens referable to B, infusorioides compare closely with the specific description and illustra- tion given by Deflandre. The test is biconical, consisting of thin, smooth endophragm and thin periphragm which bears widely spaced fairly long hair-like processes. The endo- phragm nearly fills the periphragm laterally. Dimensions: Range of 2 specimens: overall length 42 to 45 microns; overall width 30 to 33 microns. Remarks/Relationship_: P. infusorioides is reported from the Upper Cretaceous of France by Deflandre (1934) the Upper Cretaceous (Cenonmanian to Lower Turonian) of Australia (Cookson and Eisenack, 1958), and the Senonian-Campanian of Western Australia (Cookson and Eisenack, 1960). This spe— cies is restricted to the Neylandville Formation in the Austion composite section. 106 Occurrence: Rare in Neylandville Formation, Austin compos- ite section. Palaeohystrichophora sp. 1 Sp. nov. P1. 31, Figs. 5-7 Diagnosis: Test biconical, composed of smooth endophragm and periphragm densely covered with Short, fine, hair-like processes. Capsule circular to elliptical in outline, usually filling outer wall laterally, except in apical and antapical areas. Cingulum well-defined by thin marginal ridges. Two antapical horns, one of which is larger than the other. Holotype: Pb. 4579, Slide 1, coord. 47.0 x 92.5. Olmos Formation (Maestrichtian); Frio County, Texas. Dimensions: Holotype: overall length 60 microns; overall width 42 microns. Range of 4 specimens: overall length 58 to 73 microns; overall width 40 to 43 microns. Remarks/Relationships: B, Sp. 1 is distinguished from B_ infusorioides in having two antapical horns, and by its more numerous and Shorter hair-like processes. Occurrence: Common in Olmos Formation, Frio County, Texas. Genus‘Hexagonifera Type apecies: Hexagonifera gTabra Cookson and Eisenack, 1961. Upper Cretaceous; Victoria, Australia. 107 Hexagonifera sp. 1 sp. nov. P1. 31, Figs. 2—3 Diagnosis: Test oval to spherical in outline; wall moder- ately thick. Surface covered with coarse granules of variable size. Holotype: Pb. 4515, Slide 1, coord. 36.8 x 102.2. Corsi- cana Formation (Maestrichtian); Austin composite section. Dimensions: Holotype: diameter of test 31.0 microns. Range of 5 specimens: diameter of test 26-34 microns. Remarks/Relationship_: Specimens in the Navarro material referable to Hexagonifera are within the limits of the genus. Only dorso-ventrally flattened specimens were observed and thus it is difficult to determine whether the pylome is Six- sided or polygonal in outline. The small Size and distinct ornamentation distinguish this species from others described in the genus. Occurrence: Common in Neylandville Formation; abundant in Corsicana Formation; rare in Kemp Formation, Austin compos- ite section. Genus Gillinia Cookson and Eisenack, 1960 Type apecies: Gillinia nymenophora, 1960, p. 12, pl. 3, figs. 4-6. Senonian; western Australia. 108 Gillinia'hymenOphora Cookson & Eisenack, 1960 P1. 31, Fig. 8 1960. Gillinia nymenophora Cookson & Eisenack, p. 12, pl. 3, figs. 4-6. Senonian; western Australia. Discussion: The Navarro specimen referable to B. hyneno- phora agrees closely with the description and illustration given by Cookson and Eisenack. Dimensions: overall length 27 microns; overall width 20 microns. Remarka/Relationships: One specimen of B, hymenopnora was observed in the Navarro material. The species is previously recorded from the Senonian of Western Australia. Occurrence: Rare in Neylandville Formation, Austin compos- ite section. Genus Spinidinium Cookson and Eisenack, 1962 (Type species: Sanidini m grossi Alberti, 1961. Upper Hauterivian to Upper Barremian, North Germany. Spinidinium'cf.‘densiapinatum Stanley, 1965 1965. Sanidinium densiapinatum Stanley: p. 226, pl. 21, figs. 1-5. Paleocene; South Dakota. Discussion: Navarro specimens referable to B. densispinatum are close to the description and illustration given by Stanley (1965). 109 Dimensions: Range of 3 Specimens; overall length 50 to 60 microns; overall width 40 to 50 microns. Remarks/Relationships: B, densispinatum is reported by Stanley (1965) from the Paleocene of South Dakota. This Species is very abundant in samples near the base of the Olmos Formation, Frio County, Texas. Occurrence: Abundant in Frio County section, Frio County, Texas. STRATIGRAPHIC AND PALEONTOLOGIC CONSIDERATIONS List of Species in the Austin Composite Section Group ACRITARCHA Subgroup ACANTHOMORPHITAE Micrhystridium fragile. Micrhyatridium stellatum Baltisphaeridium hirsutum Baltisphaeridium sp. 1 sp. nov. Baltiaphaeridium Sp. 2 Sp. nov. Baltispnaeridium sp. 3 sp. nov. Subgroup HERKOMORPHITAE Cymatiosphaera radiata Subgroup Uncertain Palaeostomogystis sp. 1 sp. nov. Class CHLOROPHYCEAE Family Uncertain Palambages deflandrei Palambages Forma A Class DINOPHYCEAE Family HYSTRICHOSPHAERIDIACEAE Bystrichosphaeridium patulum Hystrichoaphaeridium stellatum Hystrichosphaeridium tubiferum ? Hystrichosphaeridium sp. 3 Sp. nov. Hystrichoaphaeridium sp. 1 Sp. nov. Hystrichosphaeridium sp. 2 sp. nov. i110 111 Polysphaeridium Polysphaeridium Polysphaeridium Polyaphaeridium sp. 1 Sp. sp. 2 sp. sp. 3 Sp. nov. sp. 4 sp. nov. nov . nov . Cordosphaeridium Cordosphaeridium fibrospinosum inodes Cordosphaeridium Oligosphaeridium Tanyosphaeridium Tanyosphaeridium sp. 1 sp. nov. complex sp. 1 sp. nov. sp. 2 sp. nov. Cleistosphaeridium sp. 1 sp. nov. Forma F. sp. Forma A sp. Forma A sp. Forma A sp. 1 Gen. 1 Gen. 2 Gen. 3 Gen. et sp. nov. et sp. nov. et sp. nov. et sp. nov. Diphyes cf. colligerum Callaiospnaeridium assymetricum Systematophora sp. 1 sp. nov. Family HYSTRICHOSPHAERACEAE AchomOSphaera ramulifera Hystrichosphaera ramosa var, 1 Bystrichosphaera ramosa Bystrichosphaera Hystrichosphaera Bystrichosphaera Cannosphaergpsis sp. sp. 1 sp. 2 fenestrata Family AREOLIGERACEAE Areoligera senonensis Areoligera sp. 1 sp. nov. Areoligera sp. 2 sp. nov. Byclonephelium divaricatum Byclonepnelium Sp. 1 sp. nov. Cyclonepnelium sp. 2 sp. nov. Cyclonephelium sp. 3 Sp. nov. Forma B. sp. 1 Gen. et Sp. nov. Tenua cf. hystrix Tenua sp. 1 sp. nov. Family HYSTRICHODINIACEAE Heliodinium cf. voigti 112 Family GYMNODINIACEEI Diconodinium sp. 1 sp. nov. Gymnodinium digitus Bymnodinium nelsonense Gymnodinium westralium Gymnodinium sp. 1 Sp. nov. Bymnodinium sp. 2 sp. nov. Bymnodinium sp. 3 sp. nov. Gymnodinium sp. 4 sp. nov. Gymnodinium sp. Family GONYAULACACEAE Gonyaulax sp. 1 sp. nov. Family PSEUDOCERATIACEAE Odontochitina striatgperforata Forma C. sp. 1 gen. et sp. nov. Family DEFLANDREACEAE Deflandrea acuminata Deflandrea cooksoni Deflandrea magnifica Deflandrea microgranulata Deflandrea7pannucea ? Deflandrea sp. 1 sp. nov. Deflandrea sp. 2 sp. nov. Deflandrea sp. 3 sp. nov. Deflandrea Sp. 4 sp. nov. Deflandrea sp. 5 sp. nov. Deflandrea Sp. 6 Sp. nov. Svalbardella lidiae Family APTEODINIACEAE Apteodinium sp. 1 sp. nov. Family Uncertain Hexagonifera sp. 1 Sp. nov. PalaenBystriChpphonaflinfusoriOidag Spinidinum Sp. 113 List of Species in the Frio Section Group ACRITARCHA Subgroup ACANTHOMORPHITAE Micrhystridium fragile Baltisphaeridium sp. 2 Sp. nov. Subgroup HERKOMORPHITAE Bymatiosphaera radiata Subgroup Uncertain Paleostomogystsis Sp. 1 sp. nov. Class CHLOROPHYCEAE Family Uncertain Palambages deflandrei Palambages Forma A Class DINOPHYCEAE Family HYSTRICHOSPHAERIDIACEAE Hystrichoaphaeridium patulum Hystrichosphaeridium tubiferum Bystrichosphaeridium sp. 3 sp. nov. PoTyaphaeridium sp. 1 sp. nov. PoTysphaeridium sp. 2 sp. nov. Cordosphaeridium inodes Cordosphaeridium fibrospinosum Tanyosphaeridium sp. 1 Sp. nov. Oligosphaeridium complex Systematgphora sp. 1 sp. nov. Forma A sp. 1 Gen. et sp. nov. Forma A sp. 2 Gen. et sp. nov. Forma A sp. 3 Gen. et sp. nov. Forma F sp. 1 Gen. et sp. nov. Cleistoaphaeridium sp. 1 sp. nov. Family HYSTRICHOSPHAERACEAE Achomosphaera ramulifera Hystrichosphaera ramosa var. l Hystrichosphaera ramgsa 114 Family AREOLIGERACEA Cyglonaphelium sp. 1 sp. nov. Cyclonephelium sp. 2 sp. nov. Byclonephelium sp. 3 sp. nov. Forma B sp. 1 Gen. et Sp. nov. Areoligera senonensis Areoligera sp. 2 Sp. nov. Areoligera sp. 1 sp. nov. Family GYMNODINIACEAE Bymnodinium nelsonense Bymnodinium westralium Gymnodinium sp. 1 sp. nov. Diconodinium sp. 1 sp. nov. Family GONYAULACACEAE Gonyaulax sp. 1 sp. nov. Family DEFLANDRACEAE Deflandrea cooksoni Deflandrea magnifica Deflandrea microgranulata Deflandrea pannucea ? Deflandrea sp. 1 sp. nov. Svalbardella lilidae Family Uncertain Palaeohystrichophorahsp. 1 sp. nov. Bpinidinium cf. densiapinatum 115 Zonation and Correlations Zonation of the Austin Section Eighty-one Species of dinoflagellates and acritarchs have been recognized in rocks of the Navarro group in the Austin section in this study. The vertical distributions of 68 selected species are recorded on the range chart (Fig. 4). The Neylandville and CorSicana Formations contain a number of species which, based on data presented here, appear to have restricted ranges, whereas the Kemp Formation contains many species that are common to the Corsicana and Neyland- ville Formations as well. The Kemp has few if any restricted forms. There are 14 species that continue from the Neyland- ville through the Corsicana and Kemp Formations, and several of these have known occurrences in the Tertiary rocks from other areas. The dinoflagellate - acritarch Zones are based on the qualitative nature of the assemblages. The character- istics of the Zones are discussed below. Zone A--Zone A includes the Neylandville Formation in the sampled area. There are a total of 40 species recog- nized here in the Neylandville Formation, 18 of which are also common to the Corsicana and Kemp Formations here. The top of Zone A is marked by the uppermost (youngest) occur— rence of 18 species. Seven of these 18 species whose range here terminates at the top of Zone A (Odontochitina striatoperforata, Heliodinium cf. voigti, Callaiosphaeridium 116 6(me .2_._.m=( I‘m! ”manta 3081....20‘ OZ( mh<13u0(._uoz_a USO» no 29.50-25.90 ._ f 6.... II I ||||||||||||| LfiIIlII-TAII IIJ.11 ‘1 ll Iv+I Ir I II 1LT i I .1! 801A“. NVI NVJNVO [I'IJI IJYIIIIILTATI IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII LrIIInr'll co HOOLVOVN - 311MONV‘IA3N OUU'A'N NVIIHDIULSS'N e coo-00000000000000.0000. e o VNVOI S 800 co 4N3)! .\ NS. .H\ CKXC or”. on... ..., N. ALEXA”. ERAS... \xmfixmxmmawxx SSEMABQTRWSRSHAwfiem v.5... H... RVs bee set two HVmVWWJMWa .3“, ‘C ,. a HMHMWQAAHSCVNRo a. ham“? XLCMW,%W¢%HM .0. name/v S 117 anymmetricum, Deflandrea verrucosa, Cannosphaeropsis fene— strata, Bymnodinium digitus, Deflandrea acuminata) were described in earlier literature from older rocks in other areas. None of these seven or Paleohystrichophora infusor- ioides, whiCh occur in the lower part of Zone A here, have been previously recorded from rocks as young as the Maes- trichtian. Although the Zone is rather rich in species, the number of individuals found in all, except a few species, is low in abundance. Gymnodinium digitum, B, nelsonense and Heliodinium sp. when present in a sample, usually occur in great abundance. The Zone is characterized in part by the abundance of these three species. The following species are considered good indicators of Zone A, whether they are found singly or in combination: Heliodinium sp., Forma C sp. 1, Odontochitina striatoperforata, Deflandrea sp. 6, Canno- spnaeropsis fenestrata, Deflandrea acuminata. The division between Zone A and Zone B should prove to be of time strati— graphic significance on a regional as well as local basis. The sharp contrast in the dinoflagellate assemblage between the Zones is probably indicative of an unconformity at the top of the Neylandville Formation, and the difference is not interpreted as facies controlled. Zone B--Zone B is characterized by a great diversity and abundance of species. The bottom of the Zone is marked 118 by the upper range of several forms described here from Zone A. The bottom of Zone B is also marked by the occurrence of 24 new forms, which are also indicated in Fig. 4. The top of the Zone is marked by the youngest occurrence of several species (see Fig. 4). The species Forma B sp. 1, Forma A sp. 1, Forma A sp. 3, Diconodinium sp. 1, Cordoaphaeridium fibrospinosum and Tanyosphaeridium sp. 1 usually occur in abundance in samples throughout the Zone. Zone C--The bottom of Zone C is marked by the highest occurrence of several species (see Fig. 4). The top of the Zone is not defined in the Austin composite section as the section was not sampled higher than the top of the Kemp Formation in this area. The youngest occurrence of species first appearing here is not known and many of the forms pre- viously described in the literature and found here, are known to occur in younger sediments. There are a few spe- cies which appear to be markers for the upper part of the Zone, though, again their uppermost range is not determined here. These species are Cyglonephelium divaricatum, Balti— sphaeridium Sp. 3 and Gymnodinium westralium. Correlation of the Navarro Group, Austin and Frio Sections Figures 6-11 Show relative abundance percentages of selected dinoflagellate species used to correlate the two sections studied. Figure 12, a composite of this information, 119 shows 6 horizons which can be identified in both sections; five horizons are based on positions of maximum occurrence of different species and one horizon represents the upper- most occurrence of the genus BaTaebhystrichOphora. The upper limit of range of PalanhyStrichgphora is taken as the horizon at the top of a zone which occurs near the base of the sections. PalaeonystrichOphora sp. 1 sp. nov., is very abundant in the lowermost samples of the Frio section, and is not found above the 4254 foot depth in that well (Fig. 5). Palaeohystrichophora infusoriOides was recorded on the basis of a few specimens from the top of the Neylandville Formation in the Austin section and did not occur in younger strata there. Three horizons are defined which divide the Corsi- cana Formation into two zones in the Austin composite sec— tion and the same horizons are present in equivalent posi- tions in the Frio County section. The base of the Corsicana is marked by a high occurrence of Byolonephelium sp. 1 sp. nov., where it represents 60 percent of the dinoflagellate assemblage (Fig. 6). This high abundance is reflected in samples from the Olmos Formation, Frio County. The next horizon differentiated is represented by the maximum abun- dance of Forma A sp. 1 (Fig. 7), which is also observed in samples from the Olmos Formation. A third horizon is dif- ferentiated near the top of the Corsicana Formation and in ’02. .1» I § 5 “S, 964;“ 120 | IIIIII II|IIII| (b 6‘ o' 4'6: ~900&O‘V 00 no 0 ole. o co co. 9% 0 common: | SON'IO 0 oaavAVN NVIIHOIUISSVH FIG. 5 VERTICAL DISTRIBUTION OF SOME DINOFLAGELLATE AND ACRITARCH SPECIES, FRIO COUNTY, TEXAS. 121 .wzo~h<4m¢¢ou mhuh<4m¢ .0 mascum em no b... ca as Q] A kmmm 2H maHh<4m¢ .n mzaonm ov on On cu - p P n o J L 9mm; 2” maw no muzuh<4m¢ .o~ mxaoum 126 cm oe on ON ca conL 3 aka. z~9m=< Oman 127 .mzoaefiméoo 8.5835 oz: 5288mm on: 92 5.83 mm... 5 295258:on so 86285.1 2 22oz... a .5; «a a] :5»: .8 8232:: S355 .2 95oz Emma 2H mnoz<4>uz I3 FIG. 135 pollen-spore/microplankton ratio occurs in the middle por- tions of the Neylandville and Kemp Formations, suggesting two regressions of the sea. The top of the Kemp and the top and bottom of the Neylandville-Nacatoch are marked by trans- gressions. There are several factors which may tend to invalidate such an interpretation, notably changes in pre- vailing winds and currents, differing amounts of water run— off contributing land derived material to the depositional basin, and the proximity of vegetation to the coast (Muller, 1959; Cross, Thompson and Zaitzeff, 1967, p. 520). Analysis of benthonic and planktonic foraminifera assemblages and planktonic/benthonic ratios in respect to determining rela- tive water depth, closely correlates with the relative depth of water indicated by the pollen—spore/microplankton ratio (William N. Orr, personal communication). Sections of the Austin and Frio sections are marked by floods or high occurrences of individual Species that tend to dominate some samples. Whether or not these repre— sent fossil dinoflagellate "blooms" would be speculative. Samples from the Neylandville Formation in the Austin area are dominated by the species Gymnodinium nelsonense and Gymnodinium digitus. The base of the Corsicana Formation and samples from the Olmos Formation in Frio County are marked by high occurrences of Cyclonephelium sp. 1 sp. nov. and Forma A Sp. 1 sp. nov. The significance of these for correlative purposes has been discussed. 136 The occurrence of 41 species in common to both sections suggests that these forms were widespread geograph— ically and existed in diverse environments of deposition. PALEONTOLOGIC AND STRATIGRAPHIC CONCLUSIONS Palynologic examination of the Navarro Group sedi- ments from eastcentral and southwest Texas has revealed an abundant and varied dinoflagellate-acritarch assemblage. Analysis of the fossil assemblages indicates that some spe- cies have a restricted vertical distribution and the rela- tive abundance of species varies vertically within the group at both localities. These characters aid in the zonation, correlation, and the interpretation of environment of deposi- tion of the rocks. Establishment of assemblages or types showing sequen- tial variations in relative abundance is useful. The occur— rence of unusually large numbers of particular species is considered to have time-stratigraphic significance and such occurrences can be used as horizon markers or point correla— tions. Five such horizons have been recognized here and are used as the basis for establishing five correlative horizons in the two sections. Precise taxonomic interpretation of individual species is essential to this type of study and considerations of the effect of environment on the morphology of individual species as well as genetic factors, is requisite to good stratigraphic application or interpretation. 137 138 Comparisons of the Navarro assemblage with assem- blages reported in other works indicate that the Corsicana, Kemp, Olmos, and Escondido Formations have a close affinity with the Red Bank Formation (Maestrichtian) of the New Jersey, whereas the Neylandville—Nacatoch Formations (undif— ferentiated) from the Austin composite section contains a quite dissimilar assemblage, and it appears to represent an older age than the other formations. Many of the genera and species of the Neylandville-Nacatoch are referable to Senonian and older rocks. REFERENCES (Dinoflag.) 1959a. Uber Pseudodeflandrea n.g. Geol. Alberti, G. aus dem Mittel-Oligozan von Norddeutschland. Staatsinst. Hamburg, Mitt., vol. 28, pp. 91-2. . 1959b. 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L., Jansonius, J., and Pocock, S. A. J. 1965. Evaluation of some acritarchous hystrichosphere genera. Neues Jb. Geol. Palaont. Abh., vol. 123, pp. 167-201, pls. 18-20. Stanley, E. A. 1965. Upper Cretaceous and Paleocene plant microfossils and Paleocene dinoflagellates and hystrichosphaerids from Northwestern South Dakota. Bull. of American Paleontology, vol. 49, no. 222. Stephenson, L. W. 1941. The larger invertebrate fossils of the Navarro Group of Texas. The Univ. of Texas Publ. no. 4101. Stephenson, L. W. et a1. 1942. Correlation of the outcrop- ping Cretaceous formations of the Atlantic and Gulf Coastal Plain and Trans-Pecos Texas. Bull. Geol. Soc. Amer., vol. 53, pp. 435-448, 1 pl. Tasch, P. 1963. Hystrichosphaerids and dinoflagellates from the Permian of Kansas. MicrOpaleontology, vol. 9, pp. 332-36, pl. 1. Tasch, P., McClure, K., and Oftedahl, O. 1964. Biostratig- raphy and taxonomy of a hystrichosphere—dinoflagel- late assemblage from the Cretaceous of Kansas. 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Fr., Bull., vol. 52, nos. 9-11, pp. 584—96, pls. 1-5. Wall, D. 1965a. Microplankton, pollen and Spores from the Lower Jurassic in Britain, MicrOpaleontology, vol. 11, pp. 151-190, pls. 1—9. . 1965b. Modern hystrichospheres and dinoflagel- lates cysts from the Woods Hole region. Grana Palynologica, vol. 6, no. 2, pp. 297-314. Wall, D., and Downie, C. 1963. Permain hystrichospheres from Britain Palaeontology, vol. 5, no. 4, pp. 770- 84, pls. 112-14. Wetzel, O. 1932. Die Typen der baltischen Geschiebefeuer— steine, beurteilt nach ihrem Gehalt an Mikrofos— silien. Z. Geschiebeforsch., vol. 8, pp. 129-46, pls. 1-3. . 1933. Die in organischer Substanz erhaltenen Mikrofossilien des Baltischen Kreide-Feuersteins. Palaeontographica, vol. 77, pp. 141-88, 1-110, pls. 1-7. 1961. New microfossils from Baltic Cretaceous Flintstones. MicrOpaleontology, vol. 7, pp. 337-50. Wetzel, W. 1952. Beitrag zur Kenntnis des dan-zeitlichen Meeresplanktons. Geol. Jahrb., vol. 66, pp. 391-419, p1. A. Williams, G. L. 1963. Organic—walled microplankton of the London Clay. Unpublished doctorate thesis, Univer- sity of Sheffield, England. APPENDICES APPENDIX A 1 GLOSSARY OF DINOFLAGELLATE TERMINOLOGY ACRITARCH ANTAPEX ANTAPICAL FIELDS ANTAPICAL PLATES ANTERIOR ANTERIOR INTER- CALARY FIELDS ANTERIOR INTER- CALARY PLATES (Figs. 1-15) Non-cellular organic microfossil of unknown affinity possessing a spheri- cal, ellipsoidal, discoidal, fusiform or polygonal body that may or may not bear spines, septa, etc. The area of the hypotract other than the post-equatorial fields, the ventral fields and the posterior intercalary field if present. If tabulation cannot be discerned, the antapex is defined as that part of the hypotract furthest from the girdle (Fig. 2b). The field or fields making up the antapex on the hypotheca (Fig. 2b). The plates making up the antapex on the hypotheca (Fig. lb). Towards, or nearest to, the apex in dinoflagellates. Fields on the dorsal surface of the epitract that lie between the apical series and pre-equatorial series of fields (Fig. 2b). Plates between the pre-equatorial plates and the apical plates (Fig. lb). lThis glossary, with only slight modification, has been prepared by Dr. Graham Williams, Pan American Petrolium Corporation Research Center, Tulsa, Oklahoma, and is used here with his permission. 152 APEX APICAL ARCHEOPYLE APICAL FIELDS APICAL HORN APICAL PLATES ARCHEOPYLE BORDER BORDER PROCESS DINOFLAGELLATE CYST DEXTRAL CINGULUM CINGULUM DORSAL ENDOCOEL 153 The area of the epitract other than the pre-equatorial fields and the anterior intercalary fields when present. If tabulation is not discernable, the apex is defined as that area of epitract furthest from the girdle (Fig. 2b). An archeopyle resulting from the loss of one or more apical fields (Figs. 4, 12). The fields making up the apex on the epitract (Fig. 2). The pointed extension of the apex. The plates making up the apex on the epitheca (Fig. 1). An opening in a dinoflagellate cyst usually more or less polygonal, with shape and position related to the field pattern; occasionally rounded or appare ently irregular (Figs. 2b, 3, 4, 5, 6). The line or zone along which adjacent fields meet or are inferred to meet in a dinoflagellate cyst (Fig. 5). A process originating on a border (Fig. 5). The organic walled cyst, fossilized or not, of a dinoflagellate. It usually possesses a bilayered wall and is char- acterized by one or more of the follow- ing features: (1) Cingulum, (2) arch- .eopyle, (3) tabulation, (4) a peridi—' nioid outline, (5) an apical horn. When the right termination of the Cingulum is nearer the apex than the left (Fig. 9). Equatorial zone separating the epitract from the hypotract (Fig. 2) Side opposite the ventral side. The cavity enclosed by the endophragm (Fig . 3) . ENDOPHRAGM EPITHECA EPITHEMA EPITRACT EPITRACTAL ARCHEOPYLE EQUATORIAL ARCHEOPYLE FIELD GONAL PROCESS HELICOID CINGULUM HYPOTHECA 154 The inner wall layer of a dinoflagel- late cyst which possess two or more wall layers (Fig. 2a). The portion of the theca in a free liv- ing armored dinoflagellate which is anterior to the transverse furrow. It includes the apical, anterior inter- calary (if present) and pre-equatorial plates (Fig. lb). The field or fields whose removal gives rise to the archeopyle. It can be partly attached to or completely de- tached from the margin of the archeopyle (Figs. 2b, 7). The portion of a dinoflagellate cyst anterior to the girdle, often character— ized by an apical horn (Fig. 2a). An archeOpyle formed by rupture immedi— ately anterior to the Cingulum. This results in the major part of the epi— tract becoming detached from the rest of the dinoflagellate cyst (Fig. 6). An archeopyle formed by breakage along and within the Cingulum. This separates the main body into roughly equal halves. Fundamental area dividing the main body into series of distinct units, each field maintaining a consistent position and relation to the other fields (Fig. 2). A process originating at the point of intersection of borders (Fig. 5). When the girdle is either sinistral or dextral (Fig. 8, 9). The portion of the theca in a free liv- ing armored dinoflagellate which is posterior to the transverse furrow. It includes the post—equatorial posterior intercalary and antapical plates and most of the venter (Fig. 1b). HYPOTRACT HYSTRICHOSPHERE INTERCALARY ARCHEOPYLE INTRATABULAR PROCESS LEFT AND RIGHT LONGITUDINAL FURROW MAIN BODY MID-DORSAL LINE MID-VENTRAL LINE NON-TUBULAR PROCESS 155 The portion of a dinoflagellate cyst posterior to the Cingulum, often char- acterized by one or more horns (Fig. 2b). A general descriptive term for dinoflag- ellate cysts with a more or less spherical main body bearing several processes of one sort or another, that can be Open, closed, hollow or solid. An archeopyle resulting from the loss of one or more anterior intercalary fields (Figs 2b, 3). A process originating from the area enclosed by the borders of an individ- ual field (Fig. 4). Left and right of a dinoflagellate cyst or free living stage is defined conven- tionally with the ventral side down and the anterior end directed forward. In a free living dinoflagellate, the furrow posterior to the longitudinal flagellar pore (Fig. 1a). The portion of a dinoflagellate cyst where the endophragm and periphragm are in contact. It excludes the processes of septa that are part of the peri- phragm. In dinoflagellates an imaginary line which runs from the apex to the antapex on the ventral surface and divides the ventral surface into two usually more or less equal, areas (Fig. 11). In dinoflagellates an imaginary line which runs from the apex to the antapex on the ventral surface and divides the ventral surface into two, usually more or 1688‘ equal areas (Fig. 12). A process whose position on the main body is apparently unrelated to tabula- tion. PERICOEL PERIPHRAGM PHRAGMA PLATE PLATE OR FIELD FORMULA POST-CINGULAR FIELDS POST-CINGULAR PLATES POSTERIOR POSTERIOR INTER- CALARY FIELDS POSTERIOR INTER- CALARY PLATES PRECINGULAR ARCHEOPYLE PRE-EQUATORIAL FIELDS 156 Cavity and cavities lying between the endophragm and periphragm (Fig. 3). The outer wall layer of a dinoflagel— late cyst which possesses a bilayered wall (Fig. 2a). The wall of a dinoflagellate cyst. It comprises the endophragm and periphragm (Fig. 4). Area of division of the theca in a free living form delineated by sutures (Fig. Symbolic representation of tabulation using the following conventional abbreviations (Figs. 1, 2): ' apical " precingular ' " postcingular c cingulum " " antapical a anterior intercalary p posterior intercalary v ventral plates or fields.. A series of fields on the hypotract that are adjacent to the cingulum (Fig. 2). ' Row of plates closest to transverse furrow in hypotheca. Towards, or nearest to, the anterior in dinoflagellates (Fig. 3). Fields or field on the ventral surface of the hypotract that lie between the post—cingular series and antapical fields (Fig. 15). Plates between postcingular plates and antapical fields. An archeopyle resulting from the loss of one or more pre-equatorial fields (Fig. 5). A series of fields on the epitract that are adjacent to the cingulum (Fig. 2). PRE-EQUATORIAL PLATES PROCESS COMPLEX PYLOME SEPTUM SINISTRAL CINGULUM SUTURE TABULATION TEST THECA UNSPIRALED CINGULUM VENTER 157 Row of plates closest to transverse furrow in epithema. A distinctive arrangement of several intratabular processes, either free or united by alignment in various ways, e.g., the process complexes in Areoligera or Systematophora. A regular opening in the wall of an acritarch. Raised or thickened portion of the periphragm along a border (Fig. 5). When the left termination of the cingulum is nearer the apex than the right (Fig. 8). The junction between adjacent plates in a free living dinoflagellate along which separation may occur (Fig. 1). Number and arrangement of fields in a dinoflagellate cyst, or plates in a free living dinoflagellate (Figs. 1, 2). The overall form assumed by the peri— phragm of a dinoflagellate cyst (Figs. 3, 13b). The outer covering of cellulose or some closely related substance that encloses the cell in a free living dinoflagel- late (Fig. 1a). When the left and right terminations of the girdle are not offset on the ventral surface (Fig. 10). In a dinoflagellate cyst, the area often depressed, lying between the left and right terminations of the cingulum and the first and last fields of the pre- and post—equatorial series. Bounded anteriorly by the apical fields, posteriorly by the antapical fields (Fig. 2a). VENTRAL VENTRAL AREA VENTRAL FIELDS VENTRAL NOTCH VENTRAL TONGUE 158 Side of a dinoflagellate containing the longitudinal furrow or venter. In a free living dinoflagellate, the depressed area lying between the left and right terminations of the trans— verse furrow and the first and last plates of the pre- and post—equatorial series. Bounded anteriorly by the apical plates, posteriorly by the antapical plates (Fig. la). Fields occurring on the venter. A commonly occurring notch on the margin of an apical archeopyle in line with the venter (Fig. 4). A projection on the archeopyle margin representing the anterior part of the venter in forms with an epitractal or equatorial archeopyle (Fig. 6). 159 as .mau as .mau 3MH> A Addhzm> souusm encapsuwwsoq ouzuam ouwam \ «nuannu:< nounuomhz mouuam unou< Q HOHNDW I m0 \ .m m u m fiihufl0> Bouuah onuu>msaua \ / umuagm Hufiuouasvm:mum uumsuaau mouuam humawouousH uouuuuc< auuaam HuoHa< .hm IDHZHQHMMQ EMON qu>HA muuh 1150 uoq< non-ua< eaves aquamauq< .3. will cvaoum auguOuI=VMuoum unouh uo-uuaam o .uwoa avaoum Canons—um Ola . : o-d “Q‘ . lacunmuuom .eaoam aquam< ohm (AAMHAMNHNB .Hmru mH W \/_> flu 5 .9 DEPLANDREA % _ . ’”'—_‘L‘\\f:‘\\\\_,..rr*Apical Archeopyle ‘\ I Ventral Notch Hid Doraal Line Mid‘Ventral Line £13. 12 163 ”,;—"—§. ~. t J) figfi‘l‘RICHOSPHEARIDIUM SP. MAIN BODY fig. 13a CAPSULE HYSTRICHJSPHAERIDIUM .sp. fig. 13c Poeterior Intercalary Field \b w / “3% .‘s/ HYSTRICHOSPHAERIDIUM SP. fig. 13b PROCESS COMPLEX fig. 14 APPENDIX B SAMPLE LOCALITIES Section ip_the Vicinity 2£_Austin, Texas Corsicana Formation Travis County; Jones' Crossing Section. 1/4 mile down- stream (east) from highway bridge (U.S. 71) over Onion Creek. Section begins at lowest exposed stratum in creek bed and extends eastward up steep, high, bluff. Kemp Formation present at top of section (bright yellow clay). Total thickness 90 feet. Kemngormation Travis County; A.B. Beddow Ranch Section. Bluff of Colorado River about 1 mile due north of Garfield, Texas. Base of sections is about 50 feet above highest part of the Jones' Crossing section. Total section 40 feet. Travis County; type locality of the Littig conglomerate, near Littig, Texas. Upper Kemp and Kincaid Formation collected from out in west side of road leading south from Littig. Cut is 1.85 miles, by road, from railroad- crossing in Littig. Upper Kemp also collected in brick clay-pit on east side of road leading south from Littig. (Road leading into pit is 1.75 miles from railroad cross- ing in Littig.) Neylandville Formation Travis County; Gilleland Creek Section. Taylor marl- Neylandville Formation. Section measured on SW bank of Gilleland Creek 3.35 miles SSW of Manor on State Highway 973. Section begins in bank of creek 200 feet west of middle bridge (in three bridge sequence) and passes SW beside highway along NW side of road cut. Frio County Section Humble Oil and Refining Company, Frank Doering #1 well, located 13-1/2 miles NW of Dilley, Texas in Frio County. Top of the Navarro at 3050 feet. Bottom of the Navarro at 4370 feet. Total cored sequence 3102'-4272'. 164 PLATES EXPLANATION OF PLATES PLATE 1 Micrhystridium fragile, l x500, la—4 x1250. Micrhystridium stellatum, x500. Baltisphaeridium hirsutum, 8 x500, 8a x1250 show- ing striate wall. Baltisphaeridium sp. 1 sp. nov., 9 holotype x500. PLATE 2 Baltisphaeridium sp. 3 sp. nov., 1-la holotype x500, 2-2a x500, lb,2b x1250. Baltisphaeridium sp. 2 Sp. nov., 4 holotype x500, 3 x500, 4a x1250. gymatiosphaera radiata, 5,8,9, x1250, 5a,5b,6,7 x500. Palambages Forma A, x500. PLATE 3 Palambages deflandrei, x500. Palambages Forma A, x500. Palaeostomogystis sp. 1 sp. nov., 3 holotype x1250, 4-8 x1250. Hystrichosphaeridium tubiferum, x500. Photo- graphed by phase contrast. Oligosphaeridium complex, x500. PLATE 4 (Hystrichosphaeridium tubiferum, x500. Photo— graphed by phase contrast. Hystrichosphaeridium stellatum, x500. Cordosphaeridium nodes, x500. 5 shows precingular archeopyle. Polysphaeridium sp. 2 sp. nov., 9 holotype x500, 8,10 x500. PLATE 5 Hystrichosphaeridium patulum, l x1250, la, 3 x500. Photographed by phase contrast. Tanyosphaeridium sp. 1 sp. nov., 4-4a holotype, 4 x1250, 4a x500. Photographed by phase contrast. 166 8-10a 1 2-7 8,10-10a 9-9a,11 1-4 167 Tanyospheridium sp. 2 sp. nov. holotype x500. Photographed by phase contrast. Polysphaeridium sp. 3 sp. nov., 9 holotype x1250, 10 x1250, 8, 10a x500. 9 and 10 enlarged to show flared processes tips with entire margins. Photographed by phase contrast. PLATE 6 Polysphaeridium sp. 3 sp. nov. x500. Photographed by phase contrast. Hystrichosphaeridium sp. 3 sp. nov. x500. Photo- graphed by phase contrast. Polysphaeridium sp. 1 sp. nov. 10 holotype x500, 8 x500, 10a x1250 enlarged to show greatly flared processes tips. Polysphaeridium sp. 4 sp. nov., 9—9a holotype, 9 x500, 9a x1250, ll x1250. Photographed by phase contrast. PLATE 7 Hystrichosphaeridium sp. 1 sp. nov., 2 holotype x500, 1 x500, la x1250, 3-4 x500. Note figrilar processes structure in la. Hystrichosphaeridium sp. 2 sp. nov., 5-5a holotype x500 and x1250. ,5a x1250 shows apical archeopyle with zig-zag margin. Cleistosphaeridium sp. 1 sp. nov., 8—8b holotype, 8-8a x500, 8b x1250 showing apical archeopyle with zig-zag margin. PLATE 8 Cleistosphaeridium sp. 1 sp. nov., x500, l-la showing apical View with epithema attached, also illustrates capitate character of distal extrem- ities in some processes. Photographed by phase contrast. - Forma F sp. 1 Gen et sp. nov., 10 holotype x500, wall ruptured to form precingular archeopyle; margins of large antapical processes denticulate. PLATE 9 Diphyes cf. colligerum, l x1250 showing flat acuminate processes; 1a-2 x500. Forma A sp. 3 Gen. et sp. nov., 5 holotype x500; 3, 4-11 x500; 9 epithema. Forma A sp. 1 Gen. et sp. nov., x500. 168 PLATE 10 Forma A sp. 1 Gen. et sp. nov., 2-2a holotype x500; 1, 3-6, 8, 9-10 x500; showing fused processes above archeopyle x1250; 8a shows detail of linear reticulate endophragm x1250; l—2a, 4 illustrate apparent apical position of archeopyle due to compaction; 5, 8-10 inflated specimens. PLATE 11 Forma A sp. 2 Gen. et sp. nov., l-lb holotype x500 showing precingular archeopyle and fused appen— dage; 2—3a x500. PLATE 12 Forma A sp. 2 Gen. et sp. nov., x500. Cordosphaeridium fibrospinosum x500, 5a photo- graphed by phase contrast. PLATE 13 Cordosphaeridium fibrospinosum, x500. Photo— graphed byephase contrast. Cordosphaeridium sp. 1 sp. nov., 2 holotype x500; 3-4 x500. Callaiosphaeridium cf. asymmetricum, x500; 5-5a medial view showing 6 large cingular processes with aculei well-developed. 5-6 photographed by phase contrast. Systematophora sp. 1 sp. nov., x500; 9 view of apical archeopyle; 10 complete specimen. PLATE 14 Systematophora sp. 1 sp. nov., x500; 1-1a, 3 entire specimens; 2 specimen with detached epithema. Hystrichosphaera sp. 2 x500. Hystrichosphaera ramosa, x500. Hystrichosphaera ramosa var, 1, 9a, 11 x500; 9 x1250 showing punctate wall and cyst character of processes. PLATE 15 Achomosphaera ramulifera 1-2 x500, la x1250 show- ing granular wall, cyst—like structure near distal part of processes, and trifurcate extrem— ity. Photographed by phase contrast. Hystrichosphaera sp. 10-11 l-3a l-la 2-6a 169 Hystrichsphaera sp. 1 sp. nov. Cannosphaergpsis fenestrata, x500. PLATE 16 Cyclonephelium sp. 1 sp. nov., x500; l-la photo- graphed by phase contrast, complete specimen; 3-3a complete specimen; 2-2a holotype. Cyclonephelium sp. 3 sp. nov., x500; 4-5 complete specimens; 6-6a shows margins of apical archeo- pyle; 6 photographed by phase contrast. PLATE 17 Cyclonephelium Sp. 3 sp. nov. holotype x500. Photographed by phase contrast. Cyclonephelium sp. 2 sp. nov., x600; 6-6a holotype; 2, 4, 6 photographed by phase contrast. PLATE 18 Cyclonephelium sp. 2 sp. nov. x500. Tenua hystrix, x500. Tenua sp. 1 sp. nov., x500; 4 holotype. Areoligera sp. 2 sp. nov., x500; 7-7a photographed by phase contrast. PLATE 19 Areoligera senonensis, x500; l-la dorsal and ventral view of same specimen with open archeo- pyle. Areoligera sp. 1 sp. nov., x500; 6-6a dorsal and ventral view of same specimen with attached epithema. 6-9 photographed by phase contrast. PLATE 20 Cyclonephelium divaricatum, x500; 4a photographed by phase contrast. Forma B sp. 1 Gen. et sp. nov., 7—8a x500 showing 6 apical archeopyle delineated by 6 precingular fields; 8b x1250 showing find hair-like processes attached to membranous-like structure on ventral surface of central body; 7a, 8a, 8b, photographed by phase contrast. 1-4a 8-9,12 10-11 1-8 170 PLATE 21 Gymnodinium sp. 1 sp. nov., x1250; 2, 2-2a, 4 showing small apical archeopyle; 2a photographed by phase contrast. Gymnodinium sp., x1250. Gymnodinium sp. 4 sp. nov., x500; 7, 9 shows apical archeopyle. Gymnodinium nelsonense, 10-13 x500; 13a x1250 shows apical archeOpyle, photographed by phase contrast. PLATE 22 Gymnodinium nelsonense, x500. Gymnodinium westralium, x500. 3-4, 6 photographed by phase contrast. Gymnodinium digitus, x1250. PLATE 23 Gymnodinium sp. 4 sp. nov., x1250. Diconodinium sp. 1 sp. nov., x1250. 4 photo- graphed by phase contrast. Gonyaulax sp. 1.sp. nov., x500. 7-7a photographed by phase contrast. PLATE 24 Forma C sp. 1 Gen. et sp. nov., x500; 4 holotype, entire specimen; 1, 3, 6, specimens with detached epithema; 2, 5 epithema bearing large processes. Odontochitina striatoperforata, x500, specimens with detached epithema. PLATE 25 Heliodinium cf. voigti, x500. Photographed by phase contrast. Deflandrea acuminata, x500. Photographed by phase contrast. Deflandrea cooksoni, x500. Deflandrea micracantha, x500. PLATE 26 Deflandrea sp. 2 sp. nov., x500; 1, 2-4, 6-8 photo- graphed by phase contrast; specimens illustrate size variations amongst individuals; 1—3 from Kemp Formation, 4-8 from Corsicana Formation, Austin composite section. 6 holotype; 1, 2-5, 6-8, photographed by phase contrast. '0 171 PLATE 27 Deflandrea microgranulata, x500. 2 photographed by phase contrast. Deflandrea sp. 5 sp. nov., x500. Photographed by phase contrast. 4 holotype, shows partly detached epithema and slight protruberance of central body into antapical processes. Deflandrea sp. 6 sp. nov., x500. 5-6 shows epithema attached posteriorly, and rounded anterior portion of archeopyle. Deflandrea sp. 4 sp. nov., x500. 8, 10 photo- graphed by phase contrast to show granulate wall ornamentation and triangular archeopyle with rounded corners. 5 holotype. PLATE 28 Deflandrea sp. 4 sp. nov., x500. l photographed by phase contrast. Deflandrea pannucea, x500, photographed by phase contrast. Specimens show longitudinal wrinkles and triangular archeopyle. PLATE 29 Deflandrea pannucea, x500. Photographed by phase contrast. Deflandrea sp. 3 sp. nov., x500. 4, 5,:6 photo- .graphed by phase contrast. 4 holotype. Deflandrea magnifica, x500. Photographed by phase contrast. PLATE 30 Deflandrea magnifica, x500; l photographed by phase contrast. Figures 3-4 show smaller specimens from Escondido Formation, Frio County, Texas. Apteodinium sp. 1 sp. nov., x500. Photographed by phase contrast. 5 holotype shows large precingu- lar archeOpyle and with internal capsule in close contact with outer wall. Deflandrea sp. 1 sp. nov., x500. 7a, 8a photo- graphed by phase contrast to show archeopyle formed by loss of three plates. Svalbardella lidiae, x500. 9 photographed by phase contrast. 172 PLATE 31 Svalbardella lidiae, x500. Photographed by phase contrast. Hexagonifera sp. 1 sp. nov., x1250. Paleohystrich_phora infusorioides, x500. graphed by phase contrast. Palaeohystrichophora instorioides, x500. 6a x1250 shows fine hair- like processes. Photo- Photo- PLATE 2 PLATE 5 1 ll» 1-1111(11 11‘ III - 1 Mt)! \ \l11 ¢ 11.51. I}- J .1. “3111.111 .. 11 [It .. - I Cull. - -.\-u U r . . . 1 “1‘6. .1 (\N ....v||¥. . Q“! I 0‘ I‘..1 7 ‘ AISIV \? 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