THE EESTREBUTION €35; PLANKTGMC FOWENIFERA W M NORTHWEST G-BLF QF MEXICO Thesis 509 {he Degree 0»? 53%. D. MECHEGAN SHTE UNIVERSITY Wiliiam Norton 01':- 196.8 J i}. fr':'zsmpy1 4.11:1} ( Pk w. A . " " A ‘ a I fifid7‘fi'5322 .3" --;~. = t ,7. V. n. “’H.‘ 1.45.1.1 «'53:. ' _~ . mu“ fHESlS This is to certify that the thesis entitled The Distribution of Planktonic Foraminifera in the Northwest Gulf of Mexico presented by Will iam Norton Orr has been accepted towards fulfillment of the requirements for Ph . D . degree in m 1' / Major professor Date June 6. 1968 0-169 \ ABSTRACT THE DISTRIBUTION OF PLANKTONIC FORAMINIFERA IN THE NORTHWEST GULF OF MEXICO By William Norton Orr Populations of twenty-two species of recent planktonic Foraminifera were studied from.sediments in.the northwest Gulf of Mexico. The distribution of the species and variants of the species in the marine sediments were found to be closely related to the relative abundance, life cycle, and depth preference of living populations. Many of the distribution patterns of variants of species particularly those with secondarily calcified tests are remarkably ‘well-defined and constant with respect to depth in the northwest Gulf of beico. The distribution patterns of recent planktonics in sediments which have been outlined in this study may be of use as depth indices in fossil planktonic assemblages. Several planktonic species and variants previously unreported from.the Gulf of Mexico are recorded with their distribution in the northwest Gulf. THE DISTRIBUTION OF PLANKTONIC FORMJINIFERA IN THE NORTHWEST GULF OF MEXICO By William.Norton Orr A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Geology 1968 @533 7.7., /--27'é? Acknowledgements The author wishes to thank the following for donating the samples used in this study: Scripps Institute of Oceanography, Lamont Geological Observatory, Texas A&M ‘University, Humble Oil Company, Shell Oil Company, and Standard Oil Company of Texas. To my wife, Elizabeth, and my brother-in-law, James Ruth, thanks are given for their assistance in counting the populations studied and typing the text. Finally my thanks to the members of my dissertation committee, Dr. A.T. Cross, Dr. C.E. Prouty, Dr. {.0. Braddock, and Dr. R. Ehrlich, and particularly to the chairman Dr. Jane E. Smith, for their suggestions and criticisms of the text. ii Table of Contents Page IntrOductionOOOO0..OOOOOOOOOOOOOOOOOOOOO...OOOOOOOOOOOOOOOOOOOC Previous work..................................................3 Sample preparation and counting procedure......................6 Physical features of the area of study.........................8 Distribution of planktonics in marine sediments Part I: Interspecific distributions.....................15 Part II: Intraspecific distributions Section 1: General discussion......................20 Section 2: Secondary calcification of tests........26 Section 3: Aberrant terminal chambers..............30 Section 4: SpineS..................................34 Section 5: Bullae..................................37 Section 6: Test pigmentation.......................41 Section 7: Right and left coiling..................44 Section 8: Review and discussion...................47 Part III: Variation and distribution of populations.....50 ConclusionS..................................................101 SystematiOS..................................................104 BibliographyOOOOOOO0.....0...O.OOOOOOOOCOOOOOOOOOOOOOOI.00.00159 iii Figures and Plates Figure 1. 10. 11. 12. 13. 14. 15. 16. 17. 18. Location map..................................................5 Station localities............................................7 Bathymetry of study area......................................9 Generalized surface currents..................................11 Northwest Gulf of Mexico surface currents.....................12 Vertical distribution of salinity and temperature in the......13 northwest Gulf of Mexico Number of planktonic specimens per five gram sample in the....16 northwest Gulf of Mexico Depth habitat, basinward succession and percent of total......18 fauna for fourteen planktonic species in the northwest Gulf of Mexico Size distribution of planktonics from traverses in the........22 northwest Gulf of Mexico Size distribution of planktonics from traverses in the........23 northwest Gulf of Mexico Size distribution of planktonics from traverses in the........24 northwest Gulf of Mexico. Secondary calcification in populations of five planktonics....28 from.the northwest Gulf of Mexico Diminutive final chamber on four planktonic species...........31 Distribution of planktonics bearing aberrant final chambers...32 from the northwest Gulf of Mexico Distribution of planktonic foraminifera bearing spines........35 from sediments in the northwest Gulf of Mexico Bullae structures of five planktonic species..................38 Distribution of planktonic foraminiferal specimens with.......40 bullae structures in the northwest Gulf of Mexico Distribution of pigmented and non-pigmented specimens of......43 Globigerinoides ruber frmm sediments in the northwest Gulf of Mexico iv Figures and Plates cont. mi 19. Left and right ceiling of planktonic foraminifera from......45 sediments in the northwest Gulf of Mexico 20,41. Dis'tribution Of Species.....O0......0......00.0.00000000053-98 Plates Plate 1.0.0.000000000000000....OOOOCOOOOOOOOOCOOOOO.OOO00.00.00161 Candeina 1p” Globorotalia spp., Pulleniatina 1p: Plate 2.00.00.00.00...0..0.OO0.0.0....0.00..C.’........OO......163 Globigerinita spp., Globigerina sp ., Globigerinoides 322., Orbulina 33., Hastingerina s ., G obigerinella s ., Globoquadrina £2. Plate 3000000000000...cooo00000000000000000000oooooooeoooooooooles Globigerina 822., Globigerinita app. Int no duc ti on It has been danonstrated by a number of authors (35, 1960, Jones, 1964, Bradshaw, 1959) that living planktonic Foraminifera are invariably vertically stratified to some degree in the bathy- metric column. This vertical stratification of living specimens may involve entire populations or infraspecific variant groups within populations. Moreover, vertical stratification of species or variants of the species may cinnge rapidly in cycles as diort as twelve hours or in somewhat less ephemeral monthly or yearly cycles. Authors (Phleger and Parker, 1951, Bandy, 1951) have also noted that the accunulations of empty tests of these organisms in marine ' sediments change considerably in their compositional character in traverses from shallow to deep water. The purpose of the present study is two-fold: first to determine what, if any, relationship exists between the distribution of planktonic Foraminiferal tests in marine sediments and the vertical stratification of living specimens and, second, to establish which, if any, of the distributional patterns of empty tests in marine sediments may be utilised to make retrospecticns relative to the depth habitat and distribution of fossil populations. In order to conduct this study, an area was selected in the Gulf of Mexico with a high frequency of available samples, a relatively ‘simple bottom topography, an an absence of known strong subsurface currents. It was expected that in such an area with a minimum of extraneous operative variables the distribution patterns of living specimens might emerge as the primary factor controlling 1 the distribution patterns of the empty tests in the sediments. Prior distribution studies of planktonic Foraminifera (Phleger and Parker, 1951, Parker, 1954) have been conducted in the Gulf of Mexico. These studies differ from the present study in three respects. First, the sample frequency of the present study was substantially higher than previous studies. Second, the present study considers only the planktonic Foraminifera while prior studies considered the benthonic as well as the planktonic Foraminifera. And third, the present study considers the distribution of infraspecific variants of species as well as populations of planktonic species; whereas, prior workers considered only population or interspecific distributions. Intraspecific characters tabulated in this study included speci- men size, wall thickness, color, incidence of spines and bullae, coiling, chamber, and aperture variation and pore size. Many of these intraspecific characters, when tabulated.from.specimens in the sediments, show a close relationship to the bathymetry, temperature, and salinity variations in the northwest Gulf as well as to the known vertical distribution of living planktonics in the bathymetric column. Other intraspecific characters in the have group are apparently random with respect to the physical or biological variables mentioned. Previous'lbrk A great deal of descriptive work on the distribution of recent planktonic Fbraminifera has been done in.the last seventy-five years. Most of this work, however, has been on the areal distribution rather than on the vertical distribution of these organisms. 0f the few papers which did deal with vertical distribution, one of the earliest and most significant was that of Rhumbler, 1911, in which he described a nocturnal/diurnal vertical migration of pelagic Foraminiferal populations. Lehman, 1920, considered the areal as well as vertical distribution of pelagic Fbraminifers in_a study conducted in the north and south Atlantic. He reported the highest percentages of plankton from the upper one hundred meters of the bathymetric column. Schott, 1935, studied live plankton from.the equatorial Atlantic and reported high percentages of plankton in the upper 'water column similar to Lehman's findings. He also reported a high concentration of plankton-at one thousand meters. Emiliani, 1954, chemically analyzed the tests of a number of planktonio Foraminiferal species collected from.sediments. Using isotope ratios as a guide to the temperature at which the tests were precipitated; Emiliani suggested the probable depth habitat of a number of species of planktonic Foraminifera. 36, 1959, 1960, has been and is conducting a thorough study of the areal and vertical distribution of planktonic Fbraminifera from plankton hauls and marine sediments in the north and south 4 Atlantic. In these studies he has noted some vertical stratificatian of juvenile and adult populations and of certain variants of species. Bradshaw, 1959, studied Feraminifera from.p1ankton hauls in the Pacific and reported a temperature preference by certain species of planktonic Foraminifera. This temperature preference controls the organism's areal as well as vertical distribution. Jones, 1965, studied live planktonics from.the Caribbean area and was able to show temperature preference and vertical stratification of populations similar to those of Bradshaw, 1959. In addition, Jones, 1965, has shown the vertical and areal distribution of planktonic faunas to vary considerably over monthly and annual periods. In summary, there is abundant evidence that planktonic faunas are vertically stratified in the water column.by species and in.some cases by variants of the species. This vertical stratification.may change over very short periods (diurnal/nocturnal migration), and the faunal character of an area may change considerably over an annual period. The highest percentages of planktonic Foraminiferal faunas: are to be found living in the upper one hundred meters of the water column. While other physical and chemical variables will have an effect on the distribution.of plankton, the organisms seem to be most sensitive to temperature. In the present study, many of those known distributions of live organisms in the water column were found to correspond closely to the distribution of the empty tests in the marine sediments. The living distributions, which are not manifest in sediments, were found to be those ephemeral distributions such as nocturnal/diurnal, vertical distributions or monthly/annual fluctuations in the standing crop. § .83...» to (My? a I a3: 20:400.. _ use: Sample Preparation and Counting Procedure One hundred and twenty-seven samples were used in the present study (figure 2, page 7). These were obtained from the sample libraries of a number of petroleum companies and universities. All samples are from the upper one half inch of the sample taken in a Phleger-type coring device. The samples were processed for counting by wet sieving through a two hundred and fifty mesh screen (Tyler standard screen scale: 0.062 mm openings), dried, and randomly split into five gram.aliquots. The planktonic Fbraminifera in the samples were tabulated by counting the first two hundred specimens encountered in a random straw; When less than two hundred specimens were present in a single sample, all specimens in the sample of five grams were counted. For this reason, areal distribution of species is plotted by percentage. The only variation which was recorded for all twenty-two species was size. Specimen size was measured in millimeters using an eyepiece nficrometer and recording only the maximum diameter for each specimen. Because not every specimen in a random strew will lie flat enough to measure the maximum diameter accurately, the measurements were rounded off in the graphic presentation to the nearest tenth of a millimeter. 35:33: ‘ FIGURE 2 STATION LOCAL ITIES PLANKTONICS IN SAMPLE. Q SAMPLE: BARREN OF' PLANKTONICS O CONTOURED IN FATE-(OMS SCALE no 0 IO 20 MILES O I: ~44 or ”'5“ an ID > 9! quo 7-94 "P , V 6‘ '2' CPS 0‘ ¢ A ”a ‘ ”6’ I 7 [/8 I ‘9'» V.- .33. ' II‘ 0‘ ‘49 1’27 ‘ HOUSTON Physical Features of the Area of Study The present study of recent planktonic Foraminifera was conducted in a roughly triangular-shaped area in.the northwest Gulf of Mexico (figure 1, page 5). The area is bordered on.the west and north by the Texas coast and on the south and east by latitude 25° N and longitude 94° W'respectively. The arcuate coast line is characterized by lagoons and offshore barrier islands separated by passes at the mouths of the major rivers. The continental shelf in this area ranges in width from forty miles off Brownsville, Texas, to one hundred miles off Galveston, Texas, with an average gradient of two fathoms per mile. Topography of the continental shelf is smooth with few irregularities of greater relief than fifty feet (figure 3, page 9). No abrupt break in slope takes place between the continental shelf and slope. The limit of the shelf has been placed at one hundred fathoms where a gradual increase in gradient begins with a maximum gradient on the slope of ten fathoms per mile. The continental slope in this area ranges from sixty to one hundred miles in areal width. The upper part of the slope is characterized by rugged topography consisting of numerous high knolls and filled basins, many with closures of over one thousand feet. In the lower portion of the continental slope between one thousand fathoms and seventeen hundred fathoms, the gradient increases abruptly to a maximum of one hundred fathoms/hdle. Below seventeen hundred fathoms the Sigsbee Deep extends down twenty-two hundred fathoms and is characterized by gentle slopes and subdued relief. The northwest Gulf of Mexico is an area of converging surface FIGURE BATHYMETRY OF STUDY AREA CONTOURED IN FATHOMS SCALE :0 o no 20 E MILES 3 10 currents. Major marine surface currents in the Gulf are illustrated in figure 4, page 11. Surface currents for the northwest Gulf are presented in figure 5, page 12. From May through July surface currents flow in a predominantly northerly direction. During the remainder of the year currents flow predominantly in a westward direction. Surface currents in the Gulf of Mexico (Leipper, 1953) originate from.the Yucatan Channel (figure 4, page 11). Upon passing through the Channel and entering the Gulf the current divides in three directions: east to the Florida Straits, north to the mouth of the Mississippi River, and west across the Campeche Bank. The northward current toward the Mississippi River divides south of the Mississippi into east and ‘west currents. The Campeche current follows the coast of Mexico north and converges with the central current in the northwest Gulf of Mexico. The net predominance of these individual converging currents changes, as mentioned previously, from northward in the summer to westward in the winter months. No information was available on subsurface currents in the study area. Phleger and Parker, 1951, and Emiliani, 1954, have reported the temperature and salinity variation in the northwest Gulf of Mexico (figure 6, page 13). The open ocean temperature in the northwest Gulf above the upper boundary of the main thermocline at seventy to one hundred and twentybfive meters varies from sixty-six degrees Fahrenheit to seventy degrees Fahrenheit. Below the thermocline, little annual variation in temperature takes place. Open ocean temperature drops at an average rate of five degrees Fahrenheit per three meters of depth to a minimum cf’fbrty degrees Fahrenheit at eight hundred meters. Average temperature of the surface water decreases shoreward from.a maximum NORTHWEST GULF OF MEXICO S URFACE CURRENTS AFTER CURRAY 3960 CURRENT VECTOR VALUES "T <:_%A”T"‘L ”JD." III-'>IO. II IETEns stews FIGURE 6 VERTICAL DISTRIBUTION OF SALINITY AND TEMPERATURE IN THE NORTHWEST GULF OF MEXICO AFTER PHLEGER CONT'UENTRL SHELF AND "PEER 3L0 PE W A T E R I A 3 3 E E ‘ A V N’R To ‘ ' i s ' ..-- ." / .0 .0‘ .’o' ,l a e x .0", w,‘ 1% l / a’... fi,..« 3‘ . 2”," ,. ..o°" . .. o...,./-.: ,s’ ,. .3,.u . . ”fiktm “'“f 7° 0 e '03:???) . P760 ' 35:13.5.“ ' saith.) . ,’ Q .:.:.'o?fu ”5% :33; r 4% 0",: . 0:. H00 'fi}? Q g. ' .15. I'R ',I. . u out, IIIO 'y'g': f??? 0...: ‘ , 31!. 20:23. # '.":" new '0‘ r!“ :"inI’: ”a. a 0.1:. . use 2% VIRTIOAL ~.,4‘ Ixseclwsflouga on PROFILlhfi5 Iowan " l€95l counusunl. seal. 9 wATER uAssEs LT L 35.5 *0 TEMPERATURE '9 '° 4 19'0 n In IETEls TIIPIIATURI 0 g2 g9 fin 29 a9 shuns“: I Lon WATER IAOIEI SALIRITY HILI I. 500‘ IO'G ’ I 'o TEMPERATURE DEPTH II IETEIS DEPT" 14 of seventy-five degrees Fahrenheit to a minimum of fifty-four degrees Fahrenheit. Salinity of the offshore water in the northwest Gulf averages thirty-six and twenty-five hundreds parts per thousand to thirty-six and thirty-five hundreds parts per thousand. Variation in the salinity of offshore water in the uppermost one hundred and fifty meters of water is limited with salinity increasing sl ightly with depth accompanied by an increase in temperature. Below one hundred meters, salinity decreases to a minimum of less than thirty-five parts per thousand at six hundred to eight hundred meters (figure 6, page 13). Changes in temperature and salinity with depth in water masses overlying the middle and upper continental shelf are far more abrupt than in Offshore water masses. Salinity of the shelf water masses increases with depth in some cases as much as one part per thousand per ten feet Of depth. The temperature of shelf water masses, on the other hand, is relatively constant in vertical traverses but increases basinward at an average of one degree Fahrenheit with each succeeding ten miles from the shoreline up to twenty- five mile 5 . Distribution of Planktonics in Marine Sediments Part I: Interspecific distributions Prior work on the distribution of species of planktonic Foraminifera from sediments in the northwest Gulf of Mexico differs only slightly in procedure from the present study. With respect to interspecific distributions, this study serves to sharpen somewhat the distribution patterns recorded by Phleger and Parker, 1951. Two characteristics of planktonic faunas in sediments are the lack Of Specimens in Shallow water sediments and the basinward succession of increased species diversity. The low incidence of planktonics in coastal marine sediments is well documented in fossil as well as recent assemblages. In the northwest Gulf of Mexico planktonics are found in sediments from depths greater than.twenty-five to thirty meters. Even at thirty meters the incidence of planktonic tests in sediments is extremely low (figure 7, page 16). The number of tests per unit weight of sediment (five grams, unsieved, dry) increases gradually across the continental shelf, then rapidly to a maximum of as high as thirty thousand specimens on the lower continental slope in water depths greater than fifteen hundred meters. The low number of planktonics per unit weight Of sediment on.the continental shelf may be attributed in part to the diluting effect of the active sedimentation there (Currey, 1959). The primary factor, however, is the well documented, low frequency of the living organisms in the water masses overlying the continental shelf. Phleger, 1951, has suggested that this low planktonic frequency in shelf water 15 l6 NUMBER OF SPEClMENS IM METERS DEPTH FIGURE 7 NUMBER OF PLANKTONIO SPECIMENS PER FIVE GRAM SAMPLE IN THE NORTHWEST GULF OF MEXICO I~0000 . . r6000 i h .. -4000 e L ' . COMPOSHI 0F J 0 OEVER TRAVEREES e . P2000 umvnsmc noun or twavswss c vszIcAI. txnosnnou so-I Lo 59 I90 MILES FROM 00A8T 17 masses may be due to the physical and chemical differences between.these water masses and the open ocean water masses where living planktonic Fbraminifera reach their highest frequencies (figure 7, page 16). As additional evidence for his analysis Phleger, 1960, cites the high incidence of living planktonics in the near coastal water masses off southern Califbrnia where, because of low runoff and a circulation factor, the near shore water masses have the physical and chemical characteristics of open ocean water. The second characteristic distribution pattern which has been documented in studies is that of the basinward succession of increased species diversity. Assemblages of planktonic Fbraminifera from successively deeper sediment samples in the northwest Gulf of Mexico display a fixed order of first appearance of the individual species (figure 8B, page 18). Although this successive basinward appearance of planktOnic species has been recorded by a number of authors (Phleger and Parker, 1951, Bandy, 1951, Polski, 1959, and'Wilcoxon, 1964), considerable difference of opinion exists in the interpretation of this phenomena. Phleger and Parker, 1951-1954, have interpreted the succession as a function of the relative abundance of the individual species with respect to the entire planktonic fauna. Abundant species such as Globigerinoides ruber (D'Orbigny) and Globigerina bulloides, D'Orbigny, would therefore be the only species encountered in.shallow”water sediments where, fer reasons previously discussed, the planktonic fauna is poorly developed. Rare species, such as Globigerinita glutinata, Bronniman, would not appear in sediments except where the entire planktonic fauna is numerically well-developed I8 ‘ RI 1 E I ‘ E 3.42.5.6 s. 443.3 d. £33323 .e. 331.“... .m as 58328 .M «amazoxna e emu—430040 .0 ¢umn or .0 0 mmDOE e: 2. 3.8.3 220.223.. zmmemzoa a n oz< 20.3303 243253 .222 com. 3.22. «up: 2233 cut; 2. :23: :pnuo d 0 42:4... 1 xhamo 19 in deep water. Bandy, 1956, Polski, 1959, and'Wilcoxon, 1964, have interpreted the basinward succession as an expression of the vertical stratification of living species in the water column. According to Bandy and others, epipelagic species should be found in.sha11ow as well as deep sediments, whereas mesopelagic and bathypelagic species would impinge on the bathymetric profile and thus be found only in deeper sediments. ‘ In order to evaluate these two hypotheses, fourteen of the species for which the depth habitat is known (Jones, 1964) are illustrated with the order of successive basinward occurrence and percent of the fauna for each species recorded in the present study (figure 8, page 18). Using the depth habitat of species (figure 8 A) and species' percent (figure 8 C) as potential models for the ‘succession (figure 8 B), it may be seen that neither model corresponds to the succession precisely. A satisfactoryexplanation of the succession of planktonics in sediments lies in a discussion of the intraspeoific variants (part II of this section). Distribution Of Planktonics Part II: Intraspecific Distributions Section 1: General Discussion In order to interpret effectively the distribution patterns of planktonics in sediments, it is necessary to tabulate the distribution of variants of the species as well as the distribution of the species as a whole. Intraspecific variations, which were counted and tabulated in the course of this study, included specimen size, secondary calcification, aberrant apertures and chambers, coiling, pore frequency and size, incidence of spines and bullae, and coloration. Many of these variations have been demonstrated by authors to be significant 'with respect to the distribution and ecology of living specimens. Some of the morphological characters which are significant in living specimens were found to be reflected in planktonic populations from sediments and may be of particular use in paleoecolcgical studies. Be, 1960, Bradshaw, 1959, Murray, 1895, and others have reported a basinward increase in average specimen size in assemblages of planktonics from sediments. BJ, 1960, has reported further that populations of live Foraminifera recovered from plankton hauls in the Atlantic exhibit an increase in average size with succeedingly greater depth. He attributes the size increase in planktonics from the sediments to the vertical stratification of the living organisms in the water column. Most of the planktonic populations examined in this study display an average size succession similar to those previously described. For the purpose of discussion, specimens which are in the smallest one-third of the population size range will be 20 21 termed juveniles. Two exceptions to the size succession occur in populations of Pulleniatim obliquiloculata and Orbulina universe from 13h. northwest Gulf of Mexico (figure 9, 10, page 22, 23). Orbulina universe. has been shown byBandy, 1966, to represent an ontogenetic stage of at least three separate species of planktonic Foraminifera. The fact that Orbulina universe is a polyspecific variant of intermediate and adult specimens may explain why no juveniles of this 'species" are observed as well as why no succession of juveniles to ddults occurs in shallow to deep water sediments in the northwest Gulf. Examination of size distribution graphs (figures 9, 10, 11, pages 22, 23, 24) reveals a paucity of Juvenile specimens in the population of 'I'Sniienintinn obliquiloculata which parallels the failure of this species to conform to the size increase succession characteristic of the remainder of the planktonic fauna. The low ratio of Juvenile specimens in populations of 2. obliciiiilooulata and Orbulina universa may be due to extrinsic factors such as winncwing of specimens in the sediments or selective removal of living Juvenile specimens in the water column by currents. Craig, 1967, has reported similar disparate population distributions in Bahaman peleoypod faunas in which certain species have a notably high or low ratio of Juvenile specimens to adults. He has concluded that low or high ratios of Juveniles to adults in death assemblages, which are manifest in only one or two species out of the entire fauna, must be attributed to either differential mortality or growth rates in those species. Two additional explanations for low Juvenile-adult ratios in populations are the selective removal of the Juveniles by diagonotio solution and the removal of live Juveniles in the water IILLIIITIIS 22 GURE Fl SIZE DISTRIBUTION OF PLANKTONIOS FRO” TRAVERSES IN THE NW GULF OF HEX. I-D SPECIMENS PER POINT SIZE SPIGIUEN GLOSIOERINOIKS RUDE: H L t r s . 51:32; lM L 2’: . . e f. e. . O. . . . . . a - A - - - - . - L i . t o o soc moo .n s L L moo PULLENIATINA OBLIQULWULAT h r .. t L U 0 e ..e e e e .0 e . ' e e e e E1 3.7;...... ....‘, eoeee L: .nj.l- eeggA F a 0 e e ee e .e 0 0 e 0 e .e on e e e: '. ..e ‘ ‘ ‘ 4 A— 4 L + ‘ A ‘ ITr h ”TI—‘4‘ . 300 NO ,| ,5 I0 I GLOBIOIRIIIA muster I- . C 3 We ‘e :...: fee e e e: O 0 e. 'e'e' 0' ' ‘ L ‘ a A A A A '&O r‘ls ‘ThTT-H-B- ' Lo ' . C . O O . O 8 . . v , I e e e e 0 3 . e g . .e e e t a a a . & A U “WORM OUTERTREI t . . x h . i h n . 4 ,rr 1° ‘5 500 7'50 'J' ' v.5 lS . .. 4 guess «some sun us Is.“ 23 MILLIIETENS SIZE 'SPIGINEN , FIGURE IO suz: mflmsunou or PLANKTONIGS Fnou TRAVERSES IN Tn! NWGULF or HEX. l-IO SPECIIENS PER POINT F” I! ORBULINA UN’IVERSA ‘° . . .. : . I . Z . . . , .s . . . . . .. c. - - - g -o 0 500 I000 .l .5 LO LO GLOBIGERINOIOES SACOULIFEN j 8 SPEOIIINS l0 3‘ oil-4W0 Ls A ‘. A . . ca . . . . O 7 + "4 .5 fl. '.I"'.s""1: Le ' ' m GLOBIGENINELLA SIPIIONIFENA ' x LO _, ' . . ' . '___. l ' 3 .. . ; 2 A L - - ‘:—e .o '6 fiefi I000 4 5 L GLOOOROTALII INFLNTA Po I. 50' L A; . NE‘IENS .I .5 Lo ' seecmsu sun m an L 24 IILLINETERS SIZE SPECINEN FIGURE II SIZE DISTRIBUTION OF PLANKTONIOS FROM TRAVERSES IN THE NW GULF OF HEX. I-IO SPEOIHENS PER POINT SPECIMENS vIOO I . GLOOIOERINOIOES CONGLOBATUS F1 , bl! ‘ ' ' : :. ' ' » Go A soc I000 T' ' '1» ' 16 ' ‘ ' 15 ' F "00 quosoau‘raqa Tum!» I I. 0 e . C o e . e . . . e . H .1 I . . . . . . r , 0 000 I000 .I .5 ID I5 ,I60 I. Hasnumna PELAOIGA , .00 . I e 0 v e Z O . Q - —-:- r -, - . - - . A L - - g IO “o 500 woo .I 5 I. L (”do GLOIOROTALIA CRASSAPORNIS b L I ° 8 . . . . . ' u e e s Q j ._ n - -——- ’ a K. e . o o . e e . ! e I 3 I - 4 A A a . . h L 4 Lo 0 500 I000 .L .L L0 L5 u {'°° GLOBIGERINITA MTINATA ’ I, I . kw - v . 1 v . v O ' F o - O 40 A .A ‘. P L J A —‘ o 500 I000 .I .5 I METERS SPECIMEN SIZE IN NM. 25 column by currents during limited time intervals. Solution does indeed affect juvenile specimens in sediments from depths greater than one thousand meters (Berger, 1967). There is, however, no evidence for extensive solution of Juveniles in continental shelf and upper slope faunas. Removal of Juveniles by mrine currents during the reproductive period of Pulleniatina obliquiloculata is unlikely in as much as a number of planktonic species with high Juvenile-adult ratios reproduce during the some period as 2.. obliquilooulata (Jones, 1964; Phleger, 1951). _ ‘ Because the shallow water representatives of most of the planktonic species are Juveniles, populations with a low pr0portion of Juveniles in the depth assuablages may be poorly represented or absent in shallow water- sediments. By excluding two such species, g. obliguilo- M and OIrbulina universa, from the basinward succession (figure 8 B, page 18, it is apparent thatthe succession of planktonics in basinward traverses corresponds closely with the percent of each species (figure 8 c, page 18). Rom these considerations it is concluded that the basin- ward succession ofplanktonios (figure 8?, page 18) is primarily an oxpression of thepercent of the individual species rather than depth preference by species. Further, because the basinward succession of Plsnkt9n19 Wresénifsfl..1tam°°°!-1°9 M994 9n.s.ba-.iw.d imme- adult series, any fluctuation in the ratio of Juveniles to adults in a population ‘11]. directly affect the uppermost occurrence of that species in continental shelf sediments. Distribution of Planktonics Part II: Intraspecific Distributions Section 2: Secondary calcification of tests The accretion of a secondary crust of calcite over the surface of the test of some species of planktonic Foraminifera has been.reported by a number of authors (Ericson, 1964, Be, 1964, 1965). The secondary crust, which may be as much as fifty microns thick as compared to an average of twenty microns for the underlying foundation wall, imparts a sucrosic, snowawhite appearance to the outside of the test due to minute terminations of calcite crystals, the C axes of which are oriented normal to the test well. (Plate 1, figures 3-12) Ericson 33 31. (1961) have reported the occurrence of the secondary crust on eight separate species of planktonic Foraminifera from.deep sea cores from.the Atlantic Ocean. Be and Ericson (1963) and B; (1966) have considered in detail the structure of the secondary crust on selected species of Foraminifera and have reached two important conclusions: 1. The secondary thickening of the protozoan test is not an inorganic diagenetic process taking place after the death of the individual organism. 2. The acquisition of the secondary crust is a response by the protozoan to some extrinsic stimulus which prevails in deep waters below the epipelagic zone. The present study offers some observations relative to the depth at which the thickening process begins in these organisms in the Gulf of Mexico. Planktonic Foraminifera from the marine 26 27 sediments were counted as either having or not having the secondary crust. 36 and Ericson (1963) have reported live specimens from plankton hauls which had incipient thickening of the test in the ferm of short, blunt calcite crystals over the surface of the test. Host of the specimens counted from.the Gulf of Mexico sediments either lacked the thickening completely or had a well-developed, sugary white crust (figure 12, page 28). The disparity between dead populations and the standing crop with respect to the number of individuals in the intermediate stage of thickening suggests that the thickening process itself may be rapid. The basinward change from predominantly non-thickened to thick- walled populations is remarkably abrupt, taking place over a.very short areal distance (figure 12, page 28). Each of the four species exhibits the change from.thin to thick-walled populations at a different depth from the other species. Fbr each species, the depth at which the secondary thickening takes place is constant over the entire area of the northwest Gulf of Mexico. Be and Ericson (1963) have given three hundred to five hundred meters as the depth below which secondary thickening takes place in living specimens of Globorotalia truncatulinoides (D'Orbigny). The upper limit of this three hundred to five hundred meter zone is expressed in the distribution of populations of this species from sediments in the northwest Gulf. The depths recorded at which thickening takes place in the remaining three species in this study undoubtedly represent the upper limit of the thickening zone in the bathymetric column fer living specimens: 2, crassaformis (Galloway and Wissler), seven hundred.meters; E, oultrata (D'Orbigny), one hundred and twenty meters; 28 FIG - E I2 secousam cammcanou IN POPULATIONS or FIVE PLANNTONIOS Faun THE aw our or sex. OATNYNETRIO DISTRIIUTION OF THICKENING TNIOKENN IN TOTAL WTM . o . ' . vfioeoaouua cuusan To SPEOINENS ' 'miL—emeoao'ram M1 é 'OLOOOROTALIA ORAQNFORNIS . NUNBER OLNIOIRINOMS SAOGLIFER u ‘ ‘ A“ 4 .‘ " . A s ”O . r, - outs IN ensue enemas sun In an. 29 E? tumida (Brady) two hundred meters. In addition to the Genus Globorotalia, secondary thickening is evident in the species Globigerinoides quadrilobatus sacculifer in the northwest Gulf beginning in the interval between three hundred and four hundred meters. No secondarily thickened specimens of E. sacculifer were counted from.sediments shallower than three hundred meters (figure 12, page 28). Further consideration of secondary thickening in g. sacculifer appears in the discussion of variation of the species. Distribution of Planktonics Part II: Intraspecific Distributions Section 3: Aberrant terminal chambers 36 (1965) has described variations in the ultimate chamber in a number of north Atlantic planktonic Foraminifera. These variations may be classified into two groups where they occur in faunas from.sediments in the northwest Gulf of Mexico. Populations of Globigerinella siphonifera, Globoquadrina dutertrei, Globorotalia cultrata and Globorotalia truncatulinoides all have a considerable percentage of specimens with a diminutive final chamber (figure 13, page 31). This terminal chamber, although reduced in size and bearing a comparatively thin wall, has the same shape as previous chambers. The second type of aberrant terminal chamber described by Be (1965) is the sac structure of Globigerinoides sacculifer. This latter feature may be smaller or larger than the peniultimate chamber and has a wall similar to that of the remainder of the test, but it bears little resemblance in shape to previous chambers (figure 13, page 31). Be (1965) has noted that both the sac structure and the diminutive terminal chamber on the previously mentioned species mark the termination of’shell growth for the individual specimen. Figure 14, page 32 shows the distribution in the northwest Gulf of specimens of these five species which bear either the sac structure or the diminutive terminal chamber. Specimens bearing these aberrant terminal chambers are all in the adult size range of each population curve. The distribution of specimens with aberrant terminal chambers is directly related to the average size distribution 30 3| FIGURE I35. DIMINUTIVE FINAL CHAMBER ON FOUR_ PLANKTONIC enemas FIGURE '35 SAC VARIATION IN I o A O IGERI MULT I Pl- I POINT" GAO PNNT‘D 335 32 9"" ~— m .4 * __ r 3' ”WINTION 0F PLANNTONVIOS IEARINO AOERRANT FINAL ONAIUERS FROM THE _ ‘ GULF OF NEXIO IATHYNETRIG OISTRI‘JTION OF SPEOINENS AIERRAN T WEE TOTAL POPULA IONm p HAIEMANT OHANIERS OLOIIuNINELLA W'ERA TOTAL POPULATIGI “I I *mflw AVERAIE SPEOI‘N SIZE 3‘“ A SPECIMENS I; r § v GLOEOROTALIA TRWGATULIDDIOES A? M; DEPTH IN METERS SKOINEN SIZE IN NM. 0 fi NUIIER a v T 33 of each species in the sediments in.that the appearance of Specimens bearing the aberrant chambers oorresponflsto the initial occurrence of adult specimens on the bathymetric profile. Because aberrant terminal chambers are a function of the ontogenetic stage of an individual specimen and because the ontogenetic stages are vertically stratified in the water column, as shown in a previous discussion, the presence of‘these features is potentially of use in fossil assemblages as depth indicators. Distribution of Planktcnics Part III: Intraspecific Distributions Section 4: Spines The presence or absence of spines was recorded fer a number of planktonic species during the course of this study «(figure 15, page 35). Species which have spinose individuals in their populations includedlelobigerina bulloides, Globigerinella siphonifera, Globigerinoides Conglobatus, Globigerinoides ruber, and Hastigerina pglagica. Individuals bearing spines were rare in sediments in.the western Gulf of Mexico except in the outer shelf and upper slope areas. Live specimens from plankton tows (Bradshaw, 1959, Be’, 1958, etc.) commonly have spines. The ratio of spinose to nonspinose indivi- duals in sediments is much smaller in the western Gulf of Mexico sediments than it is in the recorded ratio of spinose to nonspinose individuals from plankton tows (BE, 1958). Spines are thus destroyed on many specimens after death by abrasion or solution. Further evidence of this secondary loss of spines in planktonics may be found in the fact that only the specimens from the uppermost portion of the sediments close to the water-sediment interface bear spines. Planktonic specimens from sediments more than five centimeters below the water-sediment interface typically have a dull tan to yellow test and frequently have very fine-grained sediments in the chambers. Fresh specimens are devoid of sediments in the chambers and have a whiter test. Spines were recorded only on the light colored specimens indicating that only the most recently deposited tests in the sediments have the spines and that spines are probably lost shortly 34 35 o .I .3 L0 LS '0 soc OLQ‘INELILA SIPINDNIFERA ’ " 1 J p O 3 5 g 8 Z ’ 8 o / I I ’ L ' A " O l A + - A - - - I0 0 soc loco .I .S I. IS now so OLODIDERIm WTUS ( U Q o I z 96* J 3 z / r » ¢ I OMA- A A A A A A A - ,v b _L _ sec lose I gs L0 Le ‘°°r V SLWIDES RUDER " f 1'. c o P an ‘ % ' a I U I 3 .' / h 2 L LAIAA LA a a n L L Lo .9; ‘ L 4mg—L_ID__J.L_ I00» A {I00 HASTIDERHA PELAOBA . I0 I fl / nl _ 00W . MID FIGURE I5 DISTRIIUTION or PLANKTONIG Foaamm‘rsaa sesame smut: recs semesters IN THE aw cuu or usxuco DATHYNETRIO DISTRIBUTION OF SPINOSE SPINOSE INDIVIDUALS IN INDIVIDUALS I THE TOTAL NATION sweesmwaeulooss T "“- AV ER“ mew SIZ 95 ensues Immune PINO' INDI IIIDUALS DE PTI'I IN NETERS SPEOINEN SIZE IN IN 36‘ after the test is deposited. The distribution of spinose individuals in the sediments does not, therefore, reflect the distribution of spinose individuals in the overlying water mass. The distribution of spinose individuals (figure 15, page 35) shows a higher proportion of spinose individuals in the Juvenile size range. Be (1960) has commented on this loss of spines by mature specimens in.his studies of live Fbraminifera from the north Atlantic. The concentration of spinose individuals in the outer shelf and upper slope fer these five species does not coincide with any concentration of Juveniles at the same depth either in the sediments or in the overlying 'water mass. It is assumed that the concentration of individuals With the highly ephemeral spines is a function of active planktonic sedimentation in the outer shelf and upper slope areas. Distribution of Planktonics Part II: Intraspecific Distributions Section 5: Bullae Small chamberlets or bullae, which partially or wholly cover the openings of primary or secondary apertures on planktonic Foraminifera (figure 16, page 38), have been utilized by some authors (Blow, 1959; Loeblich, 1957) as taxonomic features in the description of new species and genera. Studies by Bradshaw (1959) and Parker (1962) have demonstrated that bullae may not be present throughout the life cycle of the individual. As a consequence of these latter studies, many of these genera and species, which were recognized on the presence or absence of'bullae, have been placed in synonymy. Five planktonic species from sediments in the northwest Gulf had bullae-bearing individuals in their populations. These species included Globigerina digitata, Globigerinoides conglobatus, Globi gerinoides ruber, Globi gerinit a glut inata, and G1 obi gerinit a humilis. The bullae of both of the above species of Globigerinoides are small, inflated.and cover secondary apertures. Bullae of Globigerina digitata and both species of Globigerinita are all broad, flap-like, and cover the umbilical aperture of the test (figure 16, page 38). Globigerinita uvula has been reported by 36 (1967) to have bullae in populations of the species in temperate water masses in the north Atlantic. The species was rare in the northwest Gulf of Mexico, and individuals with bullae were not recorded. Bullae from specimens of planktonics in the northwest Gulf typically 37 38 39 are thin.to diaphanous and.have a surface texture and pore distribution which differ considerably from the remainder of the test. The distribution of bullae is similar to the distribution of diminutive terminal chambers in populations of other species in that the structures are developed only in.the adult portion of the population (figure 17, page 40). The distribution of individuals bearing bullae corresponds to the distribution of adult specimens of the five species in sediments in the northwest Gulf (figure 17, page 40). Populations from lower slope sediments show a reduction of individuals with the bulls structure. This decrease may be a reflection of the diagenetic solution of the thin bullae at that depth. Simdlar diagenetic solution of spines in lower slope sediments has been discussed in this study. As in the incidence of spinose individuals, the presence in the sediments of many individuals with thin bullae may reflect active pelagic sedimentation at that portion of the bathymetric profile. 40 URE l7 DISTRIBUTION OF PLANKTONIC FORAHINIFERAL SPECINENS NITH-SULLAE STRUCTURES FRON SEDINENTS IN THE NW GULF OF MEXICO- DISTRIDUTION ‘OF SPEGINENS WITH DULLAE IIINDTHHEDUALS WITH NLLAE I00 TOTAL POPULATION so museums manna TOTAL POPULATION , 7.. INDIVIDUALS wm-I emu: - c - - - \- - o o ‘ nose .1 .5 L0 L3 I0 [ I00 GLODIOERINOIDES OONGLMIATUS L 0 I u o u a. \/\/\/ e: n a 1 ‘1’ L n a . \. /\/. _o o coo I000 1 .5 LO I) no. - races DLODIOERINOIDES RUDIER p 9" '5 /\ . 1v Wk 3 i A i n A A A A . [an _o 0 3L A .5 L0 ! I00 I00 GLODIOERINITA DLUTINATA L ' I: w.- 2 I 3 b I g - . . _._ - - a . J. , .o o _ I000 . .5 50 ERINITA HUNILIS T n a a a 4L . . n #_ SOD ON .I .5 L0 LS DEPTH IN NETERS SPECIMENS SIZE IN IN Distribution of Planktonics Part II: Intraspecific Distributions Section 6: Test pigmentation Two species of planktonic Foraminifera in the northwest Gulf of Mexico include specimens in their populations which have pignented tests. All of the specimens of Globigerina rubescens recorded inthe present study have a light orange hue evenly distri- buted through the test. Populations of this small species have been reported elsewhere (Parker, 1962) with non-colored variants, but no similar variants were recorded in this study. The other pigmented species, Globigerinoides M, exhibited censiderable color variation in the Gulf of Mexico. This latter species varies from completely white specimens to specimens with a bright vermillicn red color of an equal shade on all chambers in the test. Between these two extremes are individuals with a light pink coloration on all the chambers and specimens with bright red proloculus end initial whorl and succeedingly lighter red color on the younger chambers grading into pink. The ultimate and peniultimate chambers in this latter group are commonly white. Because of the complete intergradation of color variation specimens were counted as either colorless (white) or colored to some degree. Colored and non-colored variants of Globigerinoides £u_b_e_r_ may be separated into two pepulations by size as well as by color (figure 18. page 43). Both variants have the same size range (.2m to .9mm), but colored specimens are numerically dominant in the size range from .an to .m by a ratio of almost two to one. 41 42 In the size range from .5m to .9mm the non-colored variants are the numerically dominant form by a similar ratio. In areal distribution (figure 18, page 43), non—colored specimens are the dominant form at the shallowest distribution of the species between twenty-six an! one hundred neters on the continental shelf. In sediments deeper than one hundred meters, the ratio of colored to non-colored variants is approximately equal. The low percentage of pigmented specimens in the low temperature coastal water (16° 0-180 C, figure 6, page 13) seems to agree with Be"s (1960) observation that living colored variants concentrate in water of a higher temperature range (18° C-28° 0) than the reminder of the population. Living non-pigmented specimens coexist with the pigmented variety in the temperature 18°c-27° c and are the only variety present in the temperature range 16° 0-18° C (36, 1967). Although Be (1967) has reported that some fossil specimens of g. _l_'_u_b_e_r_ still bear pigmentation (phenophytin), the persistence cfvtla piglentation in fossils is infrequent. IIhile the temperature significance ofgpigmented specimens of g. 212 may be unreliable in fossil assemblages, the feature may certainly be useful in the study of recent environments. 43 um?“ fl 1! sszuuagsziaa «cups: .2 teens Minn... a. thus. -08. 98 c 1‘ is 1 Al 1 d 4 4 1 J (Fr .. j E 68 . . r L . 9:33... 3:30... 7 O .39 _ gg-Dfltfl FL v 3:38 3 29:49:53 use fl a. cum... a. e n..u. .. t c \ v 68 L 1 2.2233 33.69.32 rm. 1 68. v azusauaot r 3:38.32. 3 295.258 :3 ; 80:443th 445.05. HIP 8. 20:303....»3 C0400 201$ tuna. nun—OZENQEOJG to azuZEUto awhzulo.a-202 ”15°85 o.¢hul>xh§l it». .2 80:25:35.. 10409 02qu to $430 ’2 Ht... 2. uhzuflaum o. w¢:o_u 024 ouhzmloz to 82.23-15.90 :3 NOILV'IfldOd 1'10]. III”. N! CIIIIOIGO OILNIIOII % { L Distribution.of Planktonics Part II: Intraspecific Distributions Section 7: Right and left coiling Throughout their geographic distribution many species of recent planktonic Foraminifera may be divided into subpopulations on the basis of right or left coiling of the test. Studies by Ericson.=£_£lf (1954) and Bandy (1960) have shown.that the direction.of coiling in planktonic Fbraminifera is apparently related to water temperature. Coiling direction of planktonic Foraminifera in the northwest Gulf of lexico was recorded to test the possibility that right and left coiling subpopulations exist in.the bathymetric column in response to the vertical temperature gradient. Mixtures of right and left coiling variants of single species or assemblages of species may also indicate the intersection of two water masses of varying temperatures. Ooiling'was tabulated for nineteen of the twenty-two species present in sedimnts cf the northwest Gulf. Two of the remaining three species, Hastigerina pelagica and Globigerinella siphonifera, are planispiral thile the third, Orbulina universa, is not coiled. Coiling in most of the populations (figure 19, page 45) is generally homogeneous. The small percentage of aberrantly coiled specimens in the populations is scattered throughout the bathymetric profile. The lack of concentrations of one coiling type for any species of any particular depth seems to indicate that no vertical stratification of coiling in.the bathymetric column exists in.the northwest Gulf of Mexico. Phleger (19d0) has suggested that many of the planktonic species in.the Gulf of Mexico are allochothoncus and 44 45 ' FIGURE l9. . an no mam comma or nauxtomc Foaasmlrsaa sacs stamens m THE an GULF or sexuco Wm 19W cwsucsama manna cLosIcsamA aussscsss ~ «Lostcsama sac-crosses uosmsamrra ctunuan sLoeoouaoama cuteness sLososonLIA caassaromm auusvunma osucmtoctana sLosoaonuA mmn sLoswsamuoss ooaeLosaws BLOIOROTAUA SGITULA W T stomssama some 0 A 1 AA A A L . L n An; I: I00 sLosnssmrra menus /\/-//\ o 4— ~ L ' A A ~+ . A - uoo was sLosIsssnma uvuu - 4L - - , 414 g n i a. . loos I00 2 g sLososouus ouuaau O 0 . . A i - ”We. a]: - i A. W p n *2 O I 95 stosoaouua TWIDA i % _,_& - - AA . AL , g 0 mo u '00 '—""'\/""r 1, v V “- 0 I :1 sLosIesslms assaults - L - A - i i in Va OLODIOIWDIO R0“! 9 - A a A . - - a - 1! Mr W V—_V""'" _ “norms TIWTUUNOIIO c x L 'k A A a i a a #1 ° Dim "L we °°° 46 that assemblages there are made up of mixed faunas of mid-latitude (ZOO-40° latitude) and low latitude (00-200 latitude) species. Many of the planktonic species which are recorded in the northwest Gulf change in coiling direction where they occur in mid-latitude and low- latitude areas in the ”Atlantic (Ericson 3:11., 1954; 36, 19,167). If the Gulf faunas were mixed theythould be heterogeneous with respect to coiling groups. Coiling, on the contrary, is generally homogeneous. loreover, the trends in coiling of northwest Gulf faunas are markedly similar to those of low latitude assemblages. The homogeneity of coiling of fauna of planktonics in the northwest Gulf suggests that most of the species coexisting there are indigenous. In fossil faunas where the species diversity is very low, a frequent characteristic of planktonic assemblages, the coiling direction of the individual species as well as the homogeneity or lack of homogeneity of coiling groups may provide a useful characteristic in identifying a particular fauna in a geographic as well as stratigraphic IODBO . Distribution of Planktonics Part II: Intraspecific Distributions Section 8: Review and discussion Although they have been separated here for purposes of discussion, intraspecific and interspecific distributions of planktonics are closely interrelated. For example, the basirward succession of planktonics in sediments is primarily a function of the relativeabundance of each species. The shallow waterflrepresentatives ofa species are, howeve'r,w,_juveniles. Thus fluctuations‘in the juvenile portion of a_death assemblage may alter the basinward succession considerably. The predominance of juvenile specimens in shallowwiter populations of a species is directly related to the known living vertical stratification of planktonics in which juveniles occupy the shallowest portions of the bathymetric column. The low frequency of all planktonics in shallow water sediments has beenattributed to the low frequency (of living specimens in coastal waters. Low frequency of planktonics in shallow sediments is also due in part to dilution by the heavy sedimentation there.._In opposition to the high frequency of Juvenile, specimens in shallow water sediments, there is.a paucity of Juveniles in marine sediments below one thousand meters. This is probably due to the diagenetic solution of the thin, fragile tests of Juveniles at these depths. Because of their geometry, spines and bullaeare two other structures on planktonic tests. which are readily affected by solution. Both of the latter features are sufficiently delicate that they may be used as a qualitative 47 48 indication of active planktonic sedimentation'where they occur in “and”?! iaaésemblagei from sediment“- ”Diminutive terminal chambers, bullae structures, and secondary calcification occur in.higher frequency in adults than.in juvenile specimens, and apparently they represent late stages in the ontogenetic development. Because the above features are associated ‘with a particular specimen size, flucutations in the size distribution of populations bearing the stducture will directly affect the distribution of that feature in sediments. Secondary calcification occurs in four species of a single genus. Each of the four species changes from normal to predominantly secondarily calcified populations at separate and remarkably constant depths. The distribution of secondarily calcified individuals in sediments corresponds to the known distribution of living specimens in the bathymetric column. Test pigmentation of the planktonic species, Globigerinoides 52235, has been reported as persistant in some fossil assemblages. The tendency for pigmentation to be lost in specimens after death of the individual, however, makes this character unreliable in most fossil assemblages. The living distribution as well as the distribution of pigmented specimens in recent sediments correspond closely to temperature. Thus the feature might be of use in identifying marine currents of varying temperatures. Another feature which is apparently a function of temperature is the direction of coiling (right or left) or the test. Unlike test pigmentation, the coiling direction cannot be destroyed after the organismfls death unless, of course, the entire test is subject to solution. Coiling 49 direction of an assemblage may be characteristic for water masses of even slight variations in temperature. This character has proven extremely useful in marine stratigraphy and in determining the paleogeography of water masses of particular temperatures. It is interesting at this point to compare some of these features of planktonic Foraminifera to related features and known physical variables. Bullae structures, aberrant terminal chambers, and spines are all either directly or inversely related to the specimen size. Vertical stratification.of sizes and secondary calcification of the test are in turn a funcation of some unknown depth-related stimulus. This latter stimulus may be temperature, but there is no experimental supporting evidence. Temperature is apparently the physical variable which controls the test pigmentation and coiling as well as the distribution of individual species (interspeoific distributions). Direction of test coiling and distribution of individual species are the features most commonly used in marine stratigraphy. Authors employing these features are then in effect correlating temperature and not time. Analogs to this situation exist where some correlations based on floras are climate correlations instead of time. Distribution of Planktonics Part III: Variation and distribution of populations In preceeding sections, morphological variations which may apply to all or a number of species have been discussed separately. From these discussions certain generalities were arrived at which may be applicable in fossil assemblages. In the present section the distribution and variation of individual species are considered. For each species the distribution is contoured for the northwest Gulf of Mexico. The contoured values for these distribution maps represent the percentage of the species with respect to the remainder of the planktonic fauna at each locality. As stated in the counting procedure section (page S), where possible two hundred specimens were counted in each sample. The numerical maximum and the percentage "maximum for a species may occur at different areas in the bathymetric profile. Globigerinoides ruber, for example, may be represented by five specimens in an entire sample from water shallower than thirty meters, but it may be one hundred percent of the fauna if it is the only species present in the sample. The lowest value would represent two specimens of a species in a minute faunal count of two hundred specimens. This value contoured on the distribution maps is one percent. Rare species which are represented frequently by a single specimen, as, for example, Globigerina digitata and Globi gerina rubescens, appear to have disjunct distributions for this reason. Some of the very rare species discussed in this section may be allochothonous to the northwest Gulf of Mexico. Many of these species are abundant in the Caribbean and south Atlantic which are 50 51 the source areas for surface marine currents in the Gulf of Mexico (figure 4, page 11). The rarer species, including Globigerina digitata, Globigerina rubescens, Globigerinita humilis, and Gldbigerinita uvula, are previously undescribed from the northwest Gulf. These rare species may have been.overlooked because planktonics have been counted and studied by previous workers along with the benthonics. The species diversity of marine benthonic Fbraminifera in the Gulf of Mexico is characteristically high (three hundred to five hundred species). Counting the benthonics with the planktonics will invariably statistically screen out many of the rarer planktonics. Variation and Distribution of Populations Globi gerina bulloides D'Orbi gny Globigerina bulloides initially appears in the bathymetric profile between twenty-nine and thirty-one meters. This depth of first occurrence is consistent throughout the study area in the northwestGulf of Mexico. Average size of the specimens of this species ranges’from .2 min populations collected at the shallow end of the traverses to .4rmn.'_ in slope populations. The largest specimens were recorded from the deepest samples in the traverses and measured up to .71mn. in maximum diameter. Other variations counted for this species were spinosity and coiling. Less than ten percent of the specimens counted bear spines. These spinose individuals all occurred in continental shelf and upper slope samples. Ninety percent of the northwest Gulf specimens of E. bulloides coil to the right. Left coiling individuals are scattered throughout the bathymetric profile. Populations of Globigerina bulloides reachnumerical maximmns' at the middle and outer continental shelf where they average fifteen to twenty percent of the total planktonic fauna. On the contiental slope, population percentages of the species drop off rapidly to averages of five to ten percent. 52 53 - F'GURE 20 I': xDlSTRIBUTION OF' HOUSTON ‘3'. -. $.‘~-. -. . mm W SCALE to o no 20 96° E MILES Globigerina digitata Brady Although Globigerina digitata was rare in the western Gulf of Mexico, ninety percent of the specimens were in the shelf samples. A similar distribution.was noted by Parker (1958) in.her study of Mediterranean planktonics where she reported that, although G. digitata is less than one percent of'the total planktonic fauna, it occurs consistantly high in the bathymetric profile in continental shelf sediments. Specimens counted in this study averaged .me. Due to the rare occurrence of the species, however, no generalities can.be made on size distribution with relation to the bathymetric profile. The increased abundance of live and dead specimens reported for this species in the Caribbean Sea and the equatorial Atlantic (361 1986) seems to suggest that individuals of this species are being introduced into the Gulf of Mexico by marine currents flowing through the Yucatan Straits. All specimens of this species coil to the right in the northwest Gulf of Mexico. Approximately half of the northwest Gulf specimens of E, digitata bear a flap-like umbilical bulla. Most of these bullae-bearing individuals were counted from outer shelf and upper continental slope sediments. 54 55 F IGURE 2| XDISTRIB §Losae R'INA DIGITATAHO SCALE IO 0 '0 2° 96° E M ! LES Globigerina pachyderma (Ehrenberg) This species was rare in the western Gulf of Mexico. The specimens averaged .4mm. in size and showed little size variation. Although the species is believed by some authors to live at depths of one hundred meters and greater in temperate and tropical regions, many of the specimens counted in the present study occurred in sediments from less than one hundred meters. Parker (1958) has stated that the species is a reliable cold water indicator in the Mediterranean Sea where it is rare in sediments shallower than three hundred and thirty-eight meters. The absence of any appreciable percentages of Globigerina paohyderma in water masses or marine sediments adjacent to the Gulf of Mexico makes any suggestions as to the source of this foraminifer in the Gulf of Mexico at best speculatory. g. pachyderma is one hundred percent right-coiling in the northwest Gulf. 56 5? FIGURE" 22 x DISTRIBUTION QLOBIGEPINA SCALE , l0 0 IO 2° MILES O HOUSTON :2“. f.- PACHYQERMA 95° Globigerina rubescens Hofker This small species is very rare and scattered in the area studied. All of the specimens counted were less than .me. maximum.diameter. There was not a sufficient number of specimens oounted.to make any generalities on the distribution of size variants. The occurrence of Globigerina rubescens in the south Atlantic as reported by Be (1986) suggests that, like Globigerina digitata, the species is being carried into the Gulf area by currents through the Yucatan Straits. All specimens of this species are left coiling in the northwest Gulf, and the test has a light orange hue. 58 59 95° 9; DlSTRIBUTION OF‘ HOUSTON 3' "-' 3'- QLOBIGEBI [3A RUBESCENS SCALE l0 0 IO 20 96 E .2 M l LE 5 ‘5 e 0 .e Globigerinella siphonifera (D'Orbigny) This species initially occurs in the bathymetric profile at around forty meters. Average size increases from Ann. on shelf specimens to .finm. on slope specimens. The largest specimens of Globigerinella siphonifera are not localized in their occurrence but are most common in shelf sediments. In addition to size variation, the presence or absence of a diminutive final chamber» was counted. A diminutive final chamber was counted on about ten percent of the specimens, and individuals with the structure were scattered throughout the bathymetric profile. Highest numerical counts for the species occurred in the outer shelf sediments, but these did not exceed twelve percent of the total planktonic fauna in any of the traverses. Spinose Juvenile individuals of 2, siphonifera are up to fifteen percent of the population in shelf sediments but are rare elsewhere . 60 6| FIGURE 24 x DISTRIBUTION or HOUSTON '_=_-' QLOEIGERINELLA SIPHONIFERA'E}. SCALE no 0 to 29 96 E MILES Globi gerinita glutinata Bromiman Specimens of Globigerinita glutinata were scattered in sediments in the northwestern Gulf of lexico. Most of the specimens counted were from outer continental shelf and slope sediments. Size for the species was .3mm. (maxinmm diameter). The population is not sufficiently large to make any generalities on the distribution of size variants. Specimens bearing the bullae structure compose approximately half of the populations counted and are most comon in sediments deeper than three hundred meters. The paucity of this species in the western and eastern Gulf of Mexico (Parker, 1954) and its'increased abundance in the Orinoco and Caribbean areas (Drooger, 1958, Jones, l9dd) indicates that the species is probably being introduced into the Gulf through the Yucatan Straits. All specimens of g. glutinata recorded in the northwest Gulf were left coiling. 62 63 FIGURE 250 X DUSTRIBUTION HOUSTON WINITAO MTINATA SCALE no 0 to 20 96 E MILES Globigerinita humilis (Brady) Globigerinita humilis was rare in the western Gulf of Mexico. The species is unreported from water masses and marine sediments adjacent to the Gulf of Mexico, but the absence of the species in previous records may be due to the extremely small size of the specimens or to mdsidentification as benthonics, Parker (1951). The species was counted from outer shelf and continental slope sediments where it has a very scattered distribution. Populations of the species averaged .me. maximum diameter with little variation in size. Three quarters of the specimens bear a thin flap-like umbilical bulla which is a ventral extension of the final chamber. 2? humilis was the most heterogeneous species tabulated with respect to coiling with a sixty to forty right-to-left coiling ratio. 65 FIGURE 26 %DISTRIBUTION OF GLOBIGERINITA HUMILIS SCALE IO 0 IO 29 ° 96 MILES 95° HOUSTos ? Globigerinita uvula (Ehrenberg) This rare species was scattered in outer shelf and slope sediments in the northwestern Gulf of Mexico. Almost all of the specimens of this species measured .2mm. (maximum diameter). As with many of the smaller rare species encountered in the present study, the increased abundance in the Orinoco area (Drooger, 1958) indicates that the species is being introduced into the Gulf from the Yucatan Straits. Populations of Globigerinita uvula were more than ninety percent left coiling in the northwest Gulf. 66 67 FIGU zDISTRIB51§o£ 7°,- SCALE 20 96 MILES GLOBIGERIN ITA UVULA HOUSTON ' ' l" .. J .....-5o{..... , Globigerinoides conglobatus (Brady) The first occurrence of Globigerinoides conglobatus is scattered in the western Gulf of Mexico between thirty and eighty meters. Specimens range in average size from..3mm. in the shallowest sediments to .7mm, in the deepest. Maximum size reached by the species is 1.0mm. in continental slope sediments. The highest numerical counts for the species were recorded in samples from.the outermost continental shelf. In these sediments the species reaches a maximum of eight percent of the total planktonic fauna. In addition to size, the presence or absence of bullae structures and spines were tabulated for this species. Specimens having the bullae structure were primarily adults and were less than twelve percent of the total population. These bullae-bearing specimens were scattered through the bathymetric profile deeper than one hundred and fifty meters. Conversely, spinose individuals were predominantly juveniles and were restricted to middle and outer continental shelf sediments. One hundred percent of the populations of E. conglobatus in the northwest Gulf are right coiling. 68 .69. "DlSTRIBUTION OF HOUSTON '1' '- 3'. 03 ”um” s W? SCALE no o to so 96 125:2!!! , MILES Globigerinoides quadrilobatus sacculifer (Brady) The first occurrence of Globigerinoides quadrilobatus sacculifer in the bathymetric profile takes place consistently at thirty to thirty-two meters. Average specimen size varies from .3mm. at the shallow end of the bathymetric profile to .5mm. in populations from slope sediments. B5 and Ericson (1963) have noted a similar range in sizes from live specimens taken in plankton tows. Their study of Atlantic planktonics demonstrated that higher proportions of smaller individuals inhabited the shallower epipelagic depths while larger specimens occupied respectively greater depths in the bathymetric column. The largest specimens of g. quadrilobatus sacculifer counted in.this study measured up to 1.0mm. maximum diameter and were frmm lower slope sediments. In addition to size variation, test thickness, coiling, and the configuration of the final chamber were tabulated for northwest Gulf populations. Specimens of G. quadrilobatus sacculifer with a thickened test have been previously identified by authors (Be, 1965) as Sphaeroidinella dehiscens. This morphological variant of g. quadrilobatus sacculifer was scattered in its occurrence in.the northwestern Gulf of’Mexico sediments but was not recorded from shallower than.three hundred meters. This agrees ‘with the known distribution of living specimens of the variant as recorded from.plankton tows (B5, 19G5, Jones, 1965). B6 (1965) reports that the thickened variant occurs live in notable frequencies only at depths greater than five hundred meters in the north Atlantic. The "Sphaeroidinella dehiscens" variant ranges in size from .dmm. to 1.0mmm The configuration of the final chamber of non-thickened 70 71 specimens of G. quadrilobatus sacculifer is frequently such that the chamber is sac-like and skewed away from the proloculus (figure 13, page 31). This aberrant chamber seems to be homologous to the diminutive terminal chamber of other planktonic species. Specimens with the sac-like final chamber were rare in the sediments shallower than one hundred and fifty meters. In sediments deeper than one hundred and fifty meters the percentage of the slid-bearing variants increases to a maximum of fifty percent of the population of the species from slope sediments. The highest numerical counts of g. guadrilobatus sacculifer occur in lower slope sediments where the species is ten to fifteen percent of the total planktonic fauna. Phleger (1960) has reported a gradual increase of the percentage of g. quadrilobatus sacculifer from the western Gulf of Mexico toward the southeast Gulf of Mexico and the Caribbean Sea. This observed easterly increase of g. Quadrilobatus sacculifer in the planktonic fauna indicates, according to Phleger (1960), that the species is being introduced into the Gulf of Mexico from the southeast. The complete spectra of Juvenile to adult specimens in the western Gulf of Mexico seems to suggest the contrary. Ovey and Wiseman (1950) have stated that large accunmlations of maximum size or adult tests in sediments would indicate an environment very suitable to the organism. Such accumulations of adult tests are the result of reproduction in which the adult test is evacuated during the process of asexual reproduction (Ovey and liseman, 1950). Ninety-five percent of the specimens of g. guadrilobatus sacculifer are right coiling in the northwest Gulf. Left coiled specimens are scattered through the bathymetric profile. 72 El, 95° FIGURE 29 . °/.DIS‘6RI'BUTION or HOUSTON? W I I SAQCULIEEB; SHOREWARD LIMIT OF POPULATIONS". WITH SECONDARY THICKENING g? SCALE _ a IO 0 IO 2° 96 :. MILES . 32:...) Globigerinoides ruber (D'Orbigny) Globigerinoides ruber is the first planktonic Foraminifer to occur in the bathymetric profile of any of the traverses of the present study. The species first occurred between twenty-six and thirty-one meters and is seldom found in.numbers greater than five specimens per sample until thirtyathree to forty meters where twenty to sixty specimens occur per sample. Between forty and one hundred meters of depth the species is approximately forty percent to sixty percent of the planktonic fauna. Below'one hundred.meters on the continental slope, the population percentages decrease to twenty or twentyafive percent of the fauna. _ Size range for the species varies from.an average of .3mm. at the shallow end of the traverses to .5mm. on the outer shelf sediments. Largest specimens of the species measured .8mm. and were tabulated from outer shelf sediments. variation tabulated for the species included color, spines, coiling, bullae structures. The color varieties of the species were recorded as either nonpcolored, colored (red) throughout the test, or colored on the initial whorl. Because the "totally red" and “red on initial chamber" specimens completely intergrade, they are recorded as ”colored". Colored specimens average .4mm, in size and make up approximately fifty percent of the populations of this species except in shallow sediments where they may be absent. Non- colored specimens average .5mm. in size. Specimens with spines and bullae structures are twenty to forty percent of the populations in outer shelf and upper slope sediments. Meat of the spinose 73 ‘/—m 74 individuals are juveniles, whereas most of the bullae-bearing individuals are in the adult size range. Studies of the cytology of this species by Freudenthal, Kossoy, and Be (1955) indicate that the species has an abundant flora of zooaxonthellae symbionts. The presence of the chlorophyll synthesizing symbionts implies that the species is restricted to the euphotic zone. Studies by Emiliani (1954) on the chemistry of planktonic Foraminifers' tests showed that E, ruber lives in the upper forty-five meters of the bathymetric column. This data correlated well with the distribution of the species in the sediments of the northwest Gulf of Mexico. Ninety percent of the specimens in populationsof _G_. M are right-coiling in the northwest Gulf. Left-coiling specimens are scattered in.she1f and slope sediments. FIGURE 30 %OISTRIBUTION or QLOBIGERINOIDE§ SCALE IO 0 '0 2° 96 E M I LE5 Globoquadrina dutertrei (D'Orbigny) Globoquadrina dutertrei first occurs in the bathymetric profile between thirty-one and fifty meters. Average specimen size varies from .4mm. at the shallow ends of the traverses to .Gtmn. in the outer shelf and slope sediments. The largest specimens of this pecies occurred in the outer shelf and upper slope sediments and measured .8mm. A (maximum diameter). In addition to size variation, the incidence of the diminutive final chamber and ceiling were tabulated for this species. Specimens bearing the diminutive final chamber were evenly dispersed throughout the bathymetric profile exceptin sediments less than one hundred meters of water. Specimens bearing diminutive final chambers were invariably in the adult size range and were twenty to thirty percent of the population of the species inmany samples. in specimens of _G_. dutertrei were right coiling in the northwest Gulf. 76 77 95" FIGURE ' 3| ' ' % DISTRIBUTION OF HOUSTON gmeoguaoamA DUTERTRE! SCALE no o lo 20 ' 96 SEE MILES ..... Globorotalia crassafcrmis Cushman Globorotalia crassafcrmisvis not a comon species in the northwest Gulf, but its distribution in any of the samples in the seven traverses studied was consistent. First occurrence of the species in the bathymetric profile was scattered in the traverses between thirty-:one and four hundred meters. Average size of specimens ranged from Arms. in the shallowest samples up to .5mm. in the deepest samples. The largest specimens of this species measured .9mm. maximum diameter and occurred in the deepest samples on the continental slope. The highest percentages of the species were in faunas from the middle and outer shelf sediments where the species was four percent of the total planktonic fauna. Populations of Globorotalia crassafcrmis exhibited the secondary calcification of the test in deep water typical of the Globorotalid species. Secondarily thickened specimens of _G_. crassafcrmis are primarily in the adult size range and are limited to continental slope sediments deeper than seven hundred meters. The transition from thin-walled populations to thick-walled populations is, as in all of the Globorotalid species, abrupt. The range of sizes of this species in the sediments of the Gulf of Mexico suggests that, although the species is relatively low in its percentage of the total fauna, it is authochthonous to the Gulf. Populations-of _G_. crassafcrmis are invariably one hundred percent left ceiling in the northwest Gulf. 78 79 95° F.6URE 32 F- ' ::' 2.: . .-:....:..z '? % DISTRIBUTION o nous-rm 3, . - QLOQOROTALIA CRASSAF’ORMIS :-...-, smcwann LIMIT or POPULATION: ,9 mm secoupanv vI-IIcKENINo um. -% SCALE I0 0 I0 2o 96° .5 MILES . 7 5M .,e- a d: . i e ‘ . x. ‘0 J? ‘ .“‘ .‘ i . " I (I a}; \f a: - Q'e ': v I : e}. "b “ .0. I. I e 0 e .' e" I a“: 1" g e - ; Globorotalia cultrata (D'Orbigny) This speciesfloccurs initially in depths between thirty-one and forty meters. Average specimen size varies from .4nm. at the shallow ends of the traverses up to .9mm. in samples from the outer shelf and continental slope. The largest specimens of this species measured 1.5mm. (maximum diameter) and occurred in continental slope sediments. The presence of a diminutive final chamber was relatively common in this species which was up to fifty percent of the population in some of the deeper samples. Most of the specimens bearing this structure are in the upper half of the size range (.7m. to 1.5mm.) and are scattered through the bathymetric profile being only rare in shallow water. Populations of Globorotalia cultrata exhibited a profound change in wall thickness due to secondary calcification at approximately one hundred and twenty meters. Near this depth, popula- tions changed from five percent thick-walled forms to more than eighty percent thick-walled forms. This change occurred in most cases in less than one mile linear distance. The highest percentages of this species in the total planktonic fauna are found in slope sediments where the species reaches highs of twenty percent. 9. cultrata is more than ninety percent left coiling in the northwest Gulf of Mexico. Aberrant left coiling specimens are scattered at all levels of the bathymetric profile. 80 8| FIGURE 33 . %DISTRIBUTION OI-Ius To'N ' QLQEO B (ITALIAo F-QI.JL'I'FRA‘I'A'- SHOREWARD LIMIT OF POPULATIONS ' WITH SECONDARY THICKENING 000-0 SCALE In 0 Io 2o 98 E MILES Globorotalia inflata (D'Orbigny) This species first occurs in the bathymetric profile between forty-five and fifty meters. The first occurrence of the species is represented by very low percentages but is consistent throughout the area of the present study. The average size of the specimens ranges from..5mm. at the shallow ends of the traverses to .5mm. in continental slope sediments. The largest specimens of this species measured .7mm. and were from outer shelf and upper slope sediments. The highest percentage of the species occurs in outer shelf and slope sediments where it is up to six percent of the total planktonic fauna in isolated samples. All specimens of G. inflata tabulated coil to the left and none of the species exhibit the secondary calcification present in four other species of Globorotalia from the northwest Gulf. 82 FIGURE 340 x DISTRIBUTION QHOEOBO 1 ALUK SCALE I0 0 I0 20 use: MILES 95° . HOUSTON f ”' F-INI'-"LA'I'A .e e .- e .e Globorotalia scitula (Brady) This species is rare in sediments from the northwest Gulf of 'Mexico seldom comprising more than two percent of the fauna in any sample. Specimens range in size from..5mm. to .8mm. Globorotalia scitula was one of two species of Globorotalia which did not show secondary calcification of the test wall. The rarity of the species in the northwest Gulf of Mexico and its scattered occurrence in the Caribbean (Jones, 19S5) and equatorial Atlantic (B5; 1958) indicates that the species is probably being supplied to the Gulf from Atlantic water masses. All specimens tabulated are left coiling in the northwest Gulf. 84 85 95" FIGURE 35 . F -~. xDISTRIBUTION OF. HOUSTON’; -‘ .11, QLOBOROIALIA sgITULA SCALE I0 0 I0 as m 96. MILES Globorotalia truncatulinoides (D'Orbigny) Globorotalia truncatulinoides occurs in the bathymetric profile initially at scattered intervals between thirty and forty meters. Average size of the specimens ranges from .4mm. at the shallow ends Of the traverses to .6mm. in continental slope samples. The largest specimens of this species occurred in slope samples and measured .9mm. (maximum.diameter). In addition to size of the test, variation in the test thickness as well as the presence or absence of a diminutive final chamber and coiling were tabulated for the species. At approximately three hundred meters, populations of Globorotalia truncatulinoides exhibit a basinward change from thin to thick tests. Above this depth, populations from sediments shallower than three hundred meters consist of more thansinety percent thinawalled individuals, whereas below that depth populations are made up of more than eighty percent thickawalled individuals. B6 and Ericson (1965) have noticed a similar distribution of live, secondarily calcified specimens of Eftruncatulinoides from net tows in the north Atlantic. In their work they did not record notable percentages of these thick-walled variants of the species above three hundred.meters. Between three hundred and five hundred meters in the north Atlantic they found living thick-walled forms to be relatively common in the bathymetric column. Most of the specimens of G. truncatulinoides which exhibited the diminutive final chamber are in the largest size range of the population (.5mm. to .9mm.) and occur throughout the bathymetric profile except in the shallowest sediments. The highest percentages of the species 86 87 occurred on the continental slope between five hundred and one thousand meters where they were frequently fifteen to eighteen percent of the total planktonic fauna. E? truncatulinoides is more than ninety percent right coiling in the northwest Gulf. The aberrant left coiling specimens are scattered through the bathymetric profile. 88 95° FIGURE 36 . %DSTRI UTION OF' H STON '2' giosoa TALIA ngugg'rugmgiogs SHOREWARD LIMIT or POPULATIONS -'-. wrm SECONDARY THIcKaNINe-mo ; SCALE -- IO 0 IO 20 96° MILES ‘ 3 Globorotalia tumida (Brady) Globorotalia tumida has a very low initial occurrence in the northwest Gulf. In most of the traverses the species first appeared at eighty to one hundred and twenty meters. Average size of the individuals of this species ranged from..4mm. at the shallow ends of the traverse up to .9mm. in populations from slope samples. The largest specimens of the species measured 1.3mm. (maximum diameter) and occurred in slope sedhments. This species, like most of the species of Globorotalia, exhibits the change from.thin-walled populations to thickawalled populations in basinward traverses, which, in this case, occurs at approximately two hundred meters. Because the species has a relatively deep first occurrence in the bathymetric profile and because the population‘- change from.thin-walled to thickawalled forms takes place abruptly at two hundred meters, the majority of the specimens counted in, this study were of the thickawalled variety. The highest percentages of this species occurred in slope sediments but seldom exceeded five percent of the total planktonic fauna. POpulations of G, tumida are ninety-five percent left-coiling in the northwest Gulf and, moreover, aberrant left coiling individuals are evenly scattered areally. 89 90 . FIGURE 37 V ‘.' % DISTRIBUTION- OF HOUSTON ‘ :'-‘.'.-..°-3.' W W '-.' :"r ‘---'.: : suoncwmo LIMIT or POPULATIONS '. . I WITH ezcouoanv THICKENING ...... g ;E , ' SCALE “3;. Io o Is 20 96 . '.° m .‘ MILES . ‘ '” . ”Jae... eeee . ’-e e. e~IQ.... up. ’I It)" .. ““30!" " M! ....a 5'“. . O .0 h“. e0 (r I... Hastigerina pl elagica (D'Orbigny) Hastigerina pelagica was the only species encountered in the present study which was more common in shelf sediments than in slope sediments. The first occurrence in the bathymetric profile of this species was scattered between seventy and one hundred and fifty meters. Average specimen size varies from Ann. at the shallow ends of the traverses to .9mm. (maximum diameter) in the outer shelf samples. The highest percentages of the species occur in middle to outer shelf sediments, but populations from these sediments do not exceed four percent of the total planktonic fauna. Below two hundred meters on the continental shelf, the percentages of Hastigerins pelagica decrease. Occurrences c: this species from slope sedmnts seldom exceed one percent of the planktonic fauna. Spinose individuals of g. pelagica are primarily in the lowest size range (.3m. to .7mm.) and are rare in sediments deeper than four hundred meters. 91 92 95° F'GURE 38 ”I. ..‘ xDlSTRIBUTIoN OF HOUSTON .1. .. .. . . A TIGERINA P LAGIC SCALE 0 '0 0 lo 20 96 m MILES Orbulina universa (D'Orbigny) Orbulina universa occurs for the first time in the bathymetric profile at scattered intervals between thirty and forty'meters. Unlike other species encountered in the present study, populations of Orbulina universa do not increase in average specimen size from the shallow to the deep ends of the traverses. Throughout the bathymetric profiles the average specimen size for this form remains at approximately .7mm. This anomalous distribution is due to the lack of juveniles and probably relates to the polyphyly of the form which is discussed in the section on systematics. The highest percentages of the form occur at scattered intervals on the continental shelf where it reaches a high of fifteen percent to sixteen percent of the total planktonic fauna. An anomalous low, unlike that of any other species distribution, occurs in a large area on the continental shelf (distribution map). 93 94 FIGURE 39° xDlSTRIBUTINO RBU INA W0 SCALE I0 o :0 2° E MILES Pulleniatina obliqueloculata (Parker and Jones) Pulleniatina obliqueloculata is one of the most abundant planktonic Foraminifera in sediments in the northwestern Gulf of Mexico. The species first occurs in.the bathymetric profile at scattered intervals between thirty and fifty-five meters. Like Orbulina universe. the species displays no increase in average size 'with depth. averaging .5mm. throughout its distribution. The highest numerical counts of this species were recorded from.outer shelf and upper slope samples where the species reached percentages of twenty to twentybfive percent of the total planktonic fauna. Extremely low percentages of this species in sediments of the Orinoco and Caribbean areas have been reported by Jones (1965) and Drooger (1968). Jones has further reported that the species is very seasonal in its occurrence in the water column in the Caribbean appearing only during the month of January but periodically making up more than ninety percent of the fauna in plankton hauls. One hundred percent of the populations of the species in the northwest Gulf are right coiling. 95 96 SCALE: IO 0 IO 20 m MILES . F'GURE 4O . . % DIST IBU‘TION or: HOUSTON °-. "- EQLLEHIATIM QQLIQUILOCULATA 96 Candeina nitida D'Orbigny Candeina nitida is rare in sediments in the northwest Gulf of’lexico. The species occurred in scattered samples in the outer shelf and upper slope sediments. Average size of specimens of this species in the western Gulf was .4mm. with very little variation. Too few specimens of this species were counted to make any'meaningful comments on.the distribution. The very low percentages and limited size variations of this species suggest that it is allochthonous to the northwestern Gulf of Hexico. Both Jones (1935) and Drooger (1958) have reported Candeina ‘éitidg from the Caribbean and Grinocc areas respectively in percentages which are considerably higher than those recorded in the presentstudy from.the western Gulf of Mexico. The distributional gradient of the populations of the species from.the northwest Gulf to the southeast Gulf suggests the species may be carried into the Gulf on the marine currents entering the Gulf from.the south at the Yucatan Channel. Populations of the species in the northwest Gulf are one hundred percent left coiling. 97 98 FIGURE 4' % DISTRIBUTION or CANDEINA NITIDA SCALE II: 0 I0 20 96° MILES Distribution of Planktonics . Part III: Variation and Distribution - Review and Discussion The high species diversity of the recent planktonic Foraniniferal fauna in the northwest Gulf is due to the presence of an assemblage of allochthonous species. There is evidence that thirty-seven percent, or eight out of twenty-two species of planktonics in this area. are being introduced into the Gulf through the Yucatan Channel (see Distribution of Populations. page. 50). These allochthonous species include Globigerina pachyderma. Candeina nitida. Globorotalia scitula. Globigerinita 51am“, Globigerinita humilis. Globigerina digitata, Globigrinita uvula. and Globigerina rubescens. Ovey and Wiseman (1950) have noted that the representation of apspecies by a limited or single size group such as Juveniles may indicate that the species is allochthonous. All eight of the above planktonics from the northwest Gulf are represented elsewhere by a complete size spectrum. These eight species are distributed outside the Gulf of Mexico in low and middle latitude water masses. Average specimen size of all eight species in the northwest Gulf is invariably in the smallest It or Juvenile size range of the known size distribution elszwhere. In addition to this apparent sorting of Juveniles. many of these species have a distributional gradient from a rare occurrence in the northwest Gulf to a semen occurrence in the southeast Gulf or south Atlantic.(BS. 1966, Drcoger, 1968). Phleger (1960) has suggested that some of the well-represented Foraminifera in the northwest Gulf may also be allochthoncus because. like some of the rare species . they exhibit a distributional 99 100 gradient increasing toward the eastern.ha1f of the Gulf. The abundance of these species, as well as their representation in the northwest Gulf by all of the size groups in their ontogeny, seems to indicate that they are indigeneous to the Gulf. The variation in the first occurrence of a species in the sediments with respect to depth is well exemplified in the distribution maps of this section. This fluctuation in initial appareance is due to the extreme paucity of each species in shallow water sediments and precludes the use of first occurrence of a species as a precise depth indicator in fossil assemblages. The incidence of secondarily calcified tests is the only phenomenon which is relatively constant with respect to depth in the northwest Gulf. Even though the occurrence of this feature corresponds closely to depth, in all probability it is controlled by a variable such as temperature which must be considered before attempting to attach significance to secondarily calcified individuals in fossil assemblages. Conclusions 1. The distribution of recent planktonic Foraminiferal species and species variants in sediments from the northwest Gulf of Mexico is directly related to the vertical and areal distribution of living species in the Gulf of Mexico. 2. Empty planktonic tests occur in very low frequencies in shallow water sediments. This low frequency corresponds to the low incidence of living specimens in the overlying coastal waters in which a combination of physical factors associated with fluvial runoff from the adjacent coast brings about conditions deleterious to the planktonic fauna. 3. Each species of planktonic Foraminifera in the northwest Gulf has a minimum depth at which it initially occurs in the marine sediments. At the minimum depth, species are represented by very few individuals all of which are in the juvenile size range for the population. The value of the minimum depth for each species fluctuates considerably because the specimens upon.which it is based, being small and rare at that depth, are often overlooked. The minimum depths or initial appearance of the various species for the entire planktonic fauna may be expressed as a succession from shalIOW'to deep water. This succession of species is itself an expression of the relative abundance of each species in the planktonic fauna. Abundant species such as Globigerinoides ruber ‘will occur high in the bathymetric profile while rare species will occur in deeper sediments. 101 102 4. The average specimen size of planktonic populations increases in sediment samples taken from.successively greater depths in the bathymetric profile. This average size increase may be attributed to the known.vertical stratification of size groups of living planktonics in the marine water in which juvenile specimens occupy the shallowest portions of the water column. In sediments from water depths greater than one thousand meters a second increase in average size occurs because of the diagenetic removal by solution of the juvenile tests below this depth. Because the shallowest specimens in the bathymetric profile are invariably juveniles, variation in the ratios of juveniles to adults in a death assemblage will affect the minimum depth at which a species occurs in sediments. 5. Thin, fragile structures on the foraminiferal test, including spines and bullae, are readily destroyed by abrasion or solution after the death of the individual bearing them. While these structures are of little use in interpreting fossil assemblages, their abundance in contemporary populations from.marine sediments may be indicative of an area of active planktonic sedimentation. Such an area occurs in.the northwest Gulf of Mexico on the outer continental shelf and upper continental slope. 6. The development of aberrant terminal chambers and secondary calcification of the test are regarded as terminal stages in the ontogeny of planktonics. The appearance of the latter feature in populations of Globorotalia spp. from sediments takes place ‘with remarkable sharpness and consistency with respect to depth. 103 The areal distribution of secondarily calcified individuals in sediments is directly related to the level that living individuals occupy in the water column. 7. Temperature is apparently the physical variable controlling the distribution of pigmented specimens of Globigerinoides ruber as well as right or left coiling populations of planktonics. The latter feature may be useful in identifying mixed water masses in which planktonics should show considerable heterogeneity with respect to coiling if the water masses are of varying temperatures. 8. The Gulf of Mexico is reported (Phleger, 1961) to have a mixed assemblage oflow and middle latitude planktonic Fbraminifera. The allochthonous species which are part of this reported mixed assemblage include some of the more abundant planktonics in the Gulf. The homogeneity of the left-right coiling ratios of these well-represented planktonics, however, indicate that they are not a mixed middle and low latitude assemblage. There is good evidence that the Gulf of Mexico planktonic fauna is composed of allochthonous and autochthonous assemblages. The allochthonous species are, however, the poorly represented species instead of the abundant types and include many species which, because of their small size and low frequency, are previously undescribed from the Gulf of Mexico. Systematics Studies of the distribution of living Foraminifera conducted over the past ten years have had considerable effect on the taxonomy of these organisms. One of the major contributions of these studies has been the evidence that many previously recognized species are ecophenotypes of other species. Most of these ecophenotypes have been designated as separate species or even genera by authors because undue taxonomic significance was attached to a secondary feature of the test. Many of these features have been discussed in this study including color, coiling, bullae, spines, Secondary calcification, aberrant chambers, and others. Because many of these ecophenotypes have since been placed in synonymy, the number of recognized species of living planktonic Fbraminifera has been reduced from about fifty to thirty. While many of the planktonic species were placed in synonymy (Parker, 1962), some of the planktonic Foraminiferal genera have been subdivided. One example of this is the genus Globigerina which has been subdivided by authors into Globigerina, Globigerinella, Globoquadrina, Globigerinita, and Globigerinoides in recent assemblages. Some of the characters utilized to define these new genera include mode of coiling (planispiral, trochospiral), supplementary apertures, spines and bullae. Further studies on the ontogeny and distribution of planktonics may demonstrate deficiencies of these features as generic characters. With some exceptions, Foramini fera identified in the course of this study have been classified after the format given by Parker (1962). 104 1791. 1828. Order Foraminifera Family Globigerinidae Carpenter, Parker and Jones, 1862 Genus Globigerina D'Orbigny, 1826 Type species Globigerina bulloides D'Orbigny, 1826 Globigerina bulloides D'Orbigny Plate 2, figure 10 a-c "Polymorphium tubercsa.gt_Globuliderae" Soldani, A. (partim) Testacecgraphiae ac Zcophytographiae, vol.1, pt.2, p.117, p1.123, fig.10 only. Globigerina bulloides D'Orbigny, Ann. Sci. Nat., ser.l, vcl.7, p.277. 1884. Globigerina bulloides D'Orbigny, Brady. Rept. Voyage Challenger, 1924. 1941. 2001., vcl.9, p.593, p1.i9, fig.7a;c. Globigerina bulloides D'Orbigny, Cushman. U.S. Natl. mus. B1111. 104' Pg7. 131.2, {13.1-40 Globigerina bulloides D'Orbigny, Cushman. Ccntr. Cushman Lab. Forum. Res., v01.17, pt.2, p.38-39, pl.10, fig.1-3. 1947. Globigerina bulloides D'Orbigny, Phleger, ZEHEE' Rept. 1950. 1951. Swedish Deep Sea Expod.,'vo1.vn, no.1, p.11, p1.1. fig.3,4,'7,8. Globigerina bulloides. D'Orbigny, Natland. G.S.A. Memoir 43, p.86, p1.10, fig.2a-c. Globigerina bulloides D'Orbigny, Phleger. G.S.A. Memoir 46, p.34, p1.19, fig.6,7. 105 1957. 1958. 1958. 1959. 1959. 1959. 1959. 1960. 1960. 1961. 106 Globigerina bulloides D'Orbigny, Bolli, Loeblich and Tappan. U.S. Natl. Mus. Bull. 215, p.31, pl.4, fig.la-c. Globigerina bulloides D'Orbigny, Parker. Rept. Swedish Deep Sea Exped., vol.8, no.4, p.276, p1.5, fig.l,2,3,4. Globigerina bulloides D'Orbigny, Drooger and'Kaasschieter. Verhandelungen der Koninklijke Nederlandse Akad. van'Weten- schappen, eerste reeks, del XXII. Reports of the Orinoco Shelf Exped., vol.IV, p.84, p1.4, fig.l6; p1.5, fig.3. Globigerina £2, Bradshaw. Contr. Cush. Found. Fbram. Res. vol.lO, pt.2, p.38, pl.6, fig.24,25. Globigerina bulloides D'Orbigny, B5. Micropaleo., vol.5, no.1, pl.l, figs.15-l7. Globigerina bulloides D'Orbigny, Blow. Bull. Amer. Paleo., vol.39, no.178, p.175, oi.9, fig.38a-c. Globigerina bulloides D'Orbigny, Bradshaw. Contr. Cush. Found. Fbram, Res., vo1.io, pt.2, §.33, pl.6, fig.1-5. Globigerina bulloides D'Orbigny, Phleger. Ecol. and Distr. of Recent Fbram.. p.223,’p1.10. Globigerina bulloides D'Orbigny, Banner and Blow. Contr. Cushman Foram. Res., vol.ll, p1.1, p.33 p1.1, fig.1,4. Globigerina bulloides. D'Orbigny, Andersen. Louisiana Geol. Survey Geol. Bull. no.35, p.119, p1.27. fig.1a-b. 107 1962. Globigerina bulloides D'Orbigny, Parker. Micrcpaleo., vol.8, 110.2, P.221, p101, figgl-Bg 1962. Globigerina calida Parker. Micropaleo., vol.8, no.2, p.221, P191, £138.9-3, 15. 1963. Globigerina bulloides Smith. Contr. Cush. Found. Foram. Res., vol.l4, pt.l, p.2, pl.l, fig.l-4. Globigerina bulloides was present in considerable percentages in all the samples examined in this study. Parker's (1962) Globigerina calida was included in synonymy here as was Bradshaw's (1959) Globigerina 3_p_. Parker (1962) distinguishes g. calida from g. bulloides by the more radial elongation of the final chambers in E, calida and by the less hispid, thinner wall in E. calida. Both the chamber elongation and wall texture and thickness were found to be continuous in their variation in specimens frmm the western Gulf of flexico study. As B6 (1959) has pointed out, juvenile specimens of g. bu11o1’dee smaller than .15 mm. in size are very difficult to distinguish from juvenile specimens of Giobigerinella siphonifera (D‘Orbigny). To circumvent the possible mixing of these species, Menus. smaller than .15mm. in the g. bulloides/Globigerinella siphonifera morphological series were not counted. Be (1960) has reported a "Globigerina bulloides" juvenile stage in the ontogenetic development of Globigerina pachyderma from.Arctic samples. The cumulation of the G. pachyderma development takes place, according to Be, as the addition of a thickened crust of calcite over the "Globigerina bulloides" stage. None of the specimens identified as g. bulloides in this study exhibited any secondary thickening of the 108 test. Phleger (1960) has reported g, bulloides as abundant in.mid latitudes. However, the species has been reported from.all of the oceans cf the world as a considerable percentage of the faunas therein. 1879. 1884. 1957. 1958. 1959. 1980. Globigerina digitata Brady Plate 2, figs. 7a-c, 83-03 Plate 3, figs. 5a-c, 6a-c Globigerina digitata Brady. Quart. Jour. Micr. 801., new ser. vol.l9, p.286. Globigerina digitata Brady. Rept. VOyage Challenger, Zool. vol.9, p.599, pl.80, figs.6-10. Hastigerinella digitata (Brady) Loeblich, Tappan, and Bolli. U.S. Nfitl. M118. 3111].. 215' P932. p1.5, fig.3&-b. Globigerina digitata Brady, Parker. Repts. Swedish Deep-Sea Exped., vol.VIII, no.4, p.276, p1.5, fig.8. Globorotalia (Hastigerinella) digitata (Brady), Banner and Bl". P‘1.°n'e°1°w' W102. P016. £13011. Globorotalia (Beella) digitata (Brady). Banner and Blow. Hicropaleo., vc1.6, no.1, p.26, fig.11. 1962. Globigerina digitata Brady, Parker. Micropaleo., vol.8, no.2. p.222, p101. £13.20-25. This species'was rare in the western Gulf of Boxicc except in shelf samples. Jones (1966) did not report this species from the Caribbean area although it has been reported by Rhunbler (1911) and Brady (1897) from equatorial stations in the Atlantic. In the Pacific, the species has what appears to be a scattered and disjunet distribution.which is probably due to its paucity in the samples examined. Parker (1958) has reported the species 109 110 from.the eastern Mediterranean in percentages as high as five percent of the total planktonic fauna. Many of the specimens counted have a previously unreported bulla on the umbilical side Globigerina pachyderma (Ehrenberg) Plate 2, figs. 5a-c 1861. Aristercspira pachyderma Ehrenberg. K. Preuss. Akad.'fiiss. Berlin, Monatsber, p.276, 277, 303. 1872. Aristerospira_pachyderma Ehrenberg. K. Preuss. Akad.‘Wiss. Lbh. Jahrg. 1873, p1.1, fig.4. 1878. Globigerina bulloides D'Orbigny; var. borealis, Brady. Ann. Mag. Nat. Hist., eer.5, vol.l, p.435, p1.21, fig.10. 1881. Globigerina bulloides D'Orbigny; Arctic variety, Brady. Ann. Mag. Nat. Hist., ser.5, vol.1, no.48, p.412. 1955. Globigerina pachyderma Phleger gt_£&3 Rept. Swedish'Deep- Sea Exped., vol.VII, no.1, p.13, pl.1, figs.l7, 18, 19, 1969. Globigerina pachyderma (Ehrenberg), Bl. Micropaleo., vol.5, no.1, P101, £15.23-24. 1959. Globigerina pachyderma (Ehrenberg), Bradshaw. Contr. Cush. Found. Pbram. Res., vol.lO, pt.2, p.36, pl.6, figs.20-25. 1960. Globigerina pachyderma (Ehrenberg), Phleger. Ecol. and Distr. of Recent Forum, p.223, text plate 10. 1960. Globigerina pachyderna (Ehrenberg), Banner and Blow. Oushnan Found. Phrase Res. Contr., vol.ll, p.4, pl.3, fig.4. 1961. Globiggrina incompta Cifelli. Cushman Fbund. Pores. Res. Contr., vol.lz, p.84, pl.4. fig.1-7. 111 112 1962. Globigerina pachyderma (Ehrenberg), Parker. Micrcpaleo., 701.8, no.2, p.224, pl.1, fig.26-35; pl.2, fig.l-6. 1963. Globigerina pachyderma (Ehrenberg), Smith. Contr. Cushman Fbund. Forum. Res., vol.l4, pt.l, p.2, figs.lS-le. Specimens of Globigerina pachyderma (Ehrenberg) counted in the course of the present study have a subcircular outline rather than the quadrate outline common in many Arctic specimens (B5, 1960; Bandy, 1950). The species only occurred rarely in the samples examined. Jones (1965) has reported this species as rare in the Caribbean area. Phleger (1960) reports the species as characteristic at high and middle latitudes. Bradshaw (1959) reports the species in the Pacific north of latitude 409 N, and the species was reported by Parker (1953) as very rare south of latitude 20° N in the Etlantic. .1 number of authors have suggested that g. pachyderma lives at depths greater than 100 m. in.temperate latitudes on the basis of specimens studied from bottom sediments. At the present time, there is insufficient data from plankton tows at such depths to test this hypothesis effectively. In a recent paper Be (1960) has suggested that reports of Globigorina bulloides from irctic waters in reality concern Juvenile specimens of g. paohyderma without the thickened test characteristic of g. pachyderma. Globigerina rubescens Hofker Plate 2, fig.3a-o 1956. Globigerina rubescens Hofker. Copenhagen.Univ. Zool. mus. Spolia, vol.15, p.234, pl.35, figs.lB-Zl. 1962. Globigerina rubescens Hcfker, Parker. Micrcpaleo., vol.8, no.2, p.226, pl.2, fig.l7-18. 1966. Globigerina rubescens Hofker, Be. Living planktonic foraminifera in the South Atlantic, paper delivered 51st Ann. Meeting, A.A.P.G. This species is rare in the western Gulf of Mexico. It is easily distinguished by its light orange color. However, Parker (1962) reported some colorless specimens from colder areas in the Pacific. Because of its small size and similarity to Juveniles of other species, the colorless specimens of this species have doubtless been frequently overlooked in plankton studies. The rare occurrence of this species'was reported in the north and south Pacific by Parker (1962) and by B5 (1966) in his preliminary'work on south Atlantic faunas. This species is previously unreported from the Caribbean area of the Gulf of Mexico. 113 Genus Globigerinella Cushman, 1927 Type species Globigerina siphonifera D'Orbigny, 1839 Globigerinella siphonifera (D'Orbigny) Plat6:2, figure 15a-c 1839. Globigerina siphonifera D'Orbigny. In de la Sagra Hist. Phys. Pol. Nat. Cuba "foraminifera", p.83, p1.4, fig.l5-18. 1879. Globigerina aequilateralis Brady. Quart. Jour. Micr. Sci., New ser., vol.19, p.285. 1884. Globigerina aequilateralis Brady. Rept. Voyage Challenger, Zool., vol.9, p.605, p1.80, fig.lB-Zl. 1917. Globigerina aequilateralis Brady; var. involuta, Cushman U.S. Natl. Mus. Proc., vol.15, no.2172, p.662. 1921. Globigerina aequilateralis Brady, Cushman. U.S. Natl. Mus. Bull., no.lOO, vol.4, p.293,'r1g.11. 1953. Globigerinella aeguilateralis (Brady), Phleger gt_a1. Repts. Swedish Deep-Sea Exped., vol.VII, no.1, p.16, pl.2, f1g30'9' 10, 11. 1957. Hastigerina aeguilateralis (Brady), Loeblich et a}, U.S. Ratl. Mus. Bull.215, p.29, p1.3, fig.ia,b. 1958. Globigerinella aequilateralis (Brady), Parker. Rept. Swedish Deep-Sea Exped., vol.VIII, no.4, p.278, pl.6, fig.5,6. 114 115 1959. Globigerinella aequilateralis (Brady), B5. Micropalec., vol.5, no.1, p.98, pl.l, figs.19, 20 and 27. 1960. Globigerinella aequilateralis (Brady), Phleger. Ecol. and Distr. of Recent Forem., p.223, p1.lO. 1960. Hastigerina siphonifera (D'Orbigny), Parker. Micropaleo., vol.6, no.1, p.22, fig.2,3. 1962. Globigerinella siphonifera (D‘Orbigny), Parker. Micropaleo., vol.8, no.2, p.228, pl.2, figs.22-28. Parker (1962) has subdivided this species into two "groups" based on their morphology and occurrence in high and low latitudes. Specimens encountered in this study are predominantly of the "low latitude" type (Parker, 1962, pl.2, figs.22-26). A few of the "high latitudei types do occur in the western Gulf of Mexico. Because of the difficulty in separating juvenile specimens of E. siphonifera from juveniles of Globigerina bulloides (B6, 1959), specimens of these two species smaller than .15mm. were not counted. Specimens of E: siphonifera frequently have an aberrant diminutive final chamber. This variant is common in the western Gulf of Mexico, occurring in most of the samples examined except those from shallow'stations. Bradshaw (1959) reports the species to be abundant in tropical and warm-temperate regions, with the highest frequencies in the equatorial regions. Brady (1884) reports the Atlantic 116 distribution as between 50° N latitude and 35° 8 latitude. This species has been used by some authors as an indicator of warm intervals in marine core sections. Genus Globigerinita Bronnimann, 1951 Type species Globigerinita naparimaensis Bronnimann, 1951 Parker (1962) includes the Genus Globigerinita along with Candeina in the Incertae Familiae. Globigerinita has been separated from the Family Globigerinidae by Parker because she believes the spines to be secondary in origin, although it is finely spinose to hispid. The genus is placed in the Family Globigerinidae here because smocthawalled specimens were not observed in this study and because of its typically globigerine architecture and accessory structures. Globigerinita glutinata (Egger) Plate 2, figure la-c; plate 2, figure 3a-c, 4a-c 1893. Globigerina glutinata Egger. Abhandl. K. Bayer, Akad. Ines. Muenchen, CL II, vol.18, p.371, pl.l3, figs.l9—21. 1911. Globigerina glutinata Egger, Rhumbler. Plankton Exped. Humbclt Stift., vol.3, p.148, pl.29, figs.l4-26; pl.33, fig.20; pl.34, fig.l. 1957. Tinophodella ambitacrena Loeblich and Tappan. ween. Acad. Sci. Jour., vol.47, no.4, p.114, figs.2-3. 1953. Globigerinita glutinata (Egger), Phleger et_al, Repts. Swedish Deep-Sea Exped., vol.VII, no.1, p.16, pl.2, figs.lZ, 13, 14, 15. 117 1957. 1958. 1958. 1962. 118 Globigerinita naparimaensis Bronnimann, Loeblich St 31! U.S. Natl. Mus. Bull. 215, p.37, pl.8, figs.la-c, 2a-c. Globigerina glutinata Egger, Drooger gt a}, Verhandl. der Koninklijke Neder. Akad. van'Wetenschappen, Afd. Naturkund., eerste reeks, deel XXII; Foraminifera of the Orinoco-Trinidad- Paria Shelf, Repts. of the Orinoco Shelf Exped., vol.IV, p.85, p1.4, fig.l9; p1.5, fig.l7. Globigerinita naparimaensis Bronnimann, Drooger 22 El’ verhandl. der Koninklije Nader. Akad. vanjwetenschappen, Afd. Naturkund., eerste reeks, deel XXII; Repts. of the Orinoco Shelf Exped., vol.lV, p.85, p1.4, fig.lS; plate 5, fig.lB. Globigerinita glutinata (Egger), Parker, Micropaleo., vol.18, no.2, p.246, pl.9, figs.l-6. In the literature various authors have subdivided Globigerinita glutinata on the presence or absence of the bulla structure. Parker (1962) has made a strong case for dropping the bulla as a specific character, and her illustrations of specimens of Globigerinita glutinata with and without the bullae support this argument. G. glutinata was common but never abundant in samples examined from the western Gulf of Mexico. Bradshaw (1959) has reported the species to be more abundant in tropical regions, with one small variety of the species ranging into subarctic water. These two varieties may 119 account for the fact that B6 (1959) considers the species cold tolerant, whereas Bradshaw (1959), Boltovskoy (1962) and others have reported it to be indicative of warm water. Jones (1965)has determined that the species in the Caribbean area has a definate preference for warmer water. Although specimens with the bullae structure were common in the western Gulf of Mexico in sediments from.deeper than one hundred and fifty meters, Jones (1965) reports that in the Caribbean area only forms without the bulla were observed. Drooger (1958) records both bullae and non bullae forms from.the Orinoco Shelf area. 1884. 1929. 1957. 1960. 1960. 1962. Globigerinita humilis (Brady) Plate 2, figure 4a-c; plate 3, figure 7a-c Truncatulina humilis Brady. Rept. Voyage Challenger, Zool. vol.9, p.665, pl.94, fig.7. Globigerina cristata Heron-Allen, Earland. Jour. Royal Micr. Soc., ser.3, vol.49, pt.4, art.27, p.331, pl.4, figs. 53-39. Globigerinita parkerae Loeblich and Tappan. ‘Wash. Acad. Sci. Jour., vol.47, p.113, p1.l, fig.l. Truncatulina humilis Brady, Banner and Blow. Cush. Found. Fbram. Res. Contr., vol.ll, p.36, pl.8, fig.l. Globigerina cristata Heron-Allen, Earland; Banner and Blow. Cush. Found. Foram. Res. Contr., vol.ll, p.10, pl.7, fig.5. Globigerinita humilis (Brady), Parker. Micropaleo., vol.8, no.2, p.249, pl.lO, figs.l-25. Although Globigerinita humilis was present in many of the deeper samples from.the western Gulf of Mexico, Jones (1965) did not report it from the Caribbean area. Similarly Parker (1954) does not record the species from.the eastern Gulf of Mexico, nor does Drooger (1958) record it from the Orinoco Shelf area. Parker (1962) has reported the species to be widely distributed in the Pacific sediments but rare in the Atlantic. Her specimens almost 120 121 invariably'have the final chamber with the lobed extension covering the umbilical side. Many specimens from the western Gulf of Mexico have no covering on the umbilical side. However, the majority of the specimens from sediments deeper than two hundred meters have the lobed extension. 1861. 1872. 1884. 1931. 1933. 1938. 1957. 1958. Globigerinita uvula (Ehrenberg) Plate 2, figure 6a-c; plate 3, figure Za-c Pylodexia uvula Ehrenberg. K. Preuss. Akad. “Hes. Berlin, Monaster, p.276, 308. Pylodexia uvula Ehrenberg. K. Akad. Wise. Berlin, Abhl., pl.24-25. Globigerina 5p. Brady. Rept. Voyage Challenger, Zool., vol.9, p.603, pl.82, fig.8,9. Globigerina bradyi Wiesner. "Die Fbraminiferen der Deutschen Suedpolar-Expedition, 1901-1903" (in Drygalski, "Deutsche Sued- Polar Expedition, 1901-1903"), deGruyter, Berlin u. Leipzig, Bd.20; Zool., Bd.12, p.133.‘ Globigerinoides minuta Natland. Calif., Scripps Inst. Oceanog., Tech. Ser., vol.3, no.lO. Globigerinoides minuta Natland. Calif. Univ., Scripps Inst. Oceanog., Tech. ser., vol.4, no.5, p.150, pl.7, fig.2-3. Globigerina bradyi ‘Wiesner, Bolli. U.S. Natl. Mus. Bull. 215’ p.110‘111' P1023, fig.5&’°o Globigerina bradyi 'Wiesner, Drooger and Kaasschieter. Verhandl. der Koninklijke Neder. Akad. van wetenschappen, Afd. Naturkunde, eerste reeks, deel XXII; Reports of the 122 123 Orinoco Shelf Exped., vol.IV, p.85, pl.4, fig.22a-c; p1.5, fig. 153-0 0 1959. Globigerina bradyi 'Wiesner, BlOW. Bull. Amer. Paleo., vol.39, no.178, p.173-4, pl.7, fig.36. 1960. Globigerina bradyi “Keener, Banner and Blow. Contr. Cush. Found. Res., vol.II, pt.l, p.5, pl.3, rig.1,2. 1960. Pylodexia uvula Ehrenberg, Banner and Blow. Cush. Found. Fbram. Res. Contr., vol.ll, p.5, pl.3, fig.3. 1962. Globigerinita uvula (Ehrenberg), Parker. Micropaleo., vol.8, no.2, p.252, pl.8, fig.l4-26. Specimens of Globigerina uvula do not occur in any of the samples counted in frequencies greater than two percent. Although Jones (1965) does not report the species for the Caribbean, Drooger (1958) has reported the species from samples on the Orinoco Shelf but notes that it only attains notable frequencies in samples from.colder water. Globigerinita 22312 has been reported in the south Pacific by Parker (1962) between latitude 40‘,S and latitude 63‘,S. Specimens counted in this study were almmst exclusively from very deep samples. Although the species is small, it is easily distinguished from juveniles of other species by its characteristic conical architecture. Parker (1962) has illustrated specimene of E. uvula with a prominent umbilical bulla. Although none of the specimens encountered in this 124 study have a bulla, they are identical to Parker's specimens without the bulla and are considered to be conspecific. 1879. 1884. 1924. 1950. 1951. 1953. 1958. 1959. Genus Globigerinoides Cushman, 1927 Type species Globigerina ruber D'Orbigny, 1839 Globigerinoides conglobatus (Brady) Plate 2, figure lla-c Globigerina conglobata Brady. Quart. Jour. Micr. Sci., New ser., vol.19, p.286. Globigerina conglobata Brady. Rept. Voyage Challenger, Zool., vol.9, pl.80, fig.l-5, pl.82, fig.5. Globigerina conglobata Brady, Cushman. U.S. Natl. Mus. Bull. 104, p.18, pl.3, figs.8-l3. Globigerinoides conglobata (Brady), Wiseman at El! Geol. Assoc. Proc., vol.61, pt.1, p168, pl.3, figs.8a,b. Globigerinoides conglobata (Brady), Phleger and Parker. Geol. Soc. of America, Mem.46, p.35, pl.19, fig.lS. Globigerinoides conglobata (Brady), Phleger 23-513 Rept. Swedish Deep-Sea Exped., vol.VII, no.1, p.15, pl.2, figs.l,2,3. Globigerinoides conglobata (Brady), Parker. Rept. Swedish Deep-Sea Exped., vol.VIII, no.4, p.279, pl.6, fig.lG, 17. Globigerinoides conglobata (Brady), Bradshaw. Cushman Found. Foram. Res. Contr., vol.lO, pt.2, p.40, pl.7, figs.5,6. 125 126 1959. Globigerinoides conglobatus (Brady) Be. Micropaleo., vol.5, no.1, p.98, pl.2, figs.7-12. 1960. Globigerinoides conglobatus (Brady) Phleger. Ecol. and Distr. of Recent Fbram., p.223, pl.lO. 1960. Globigerina conglobata Brady, Banner and Blow. Cushman Found. Foram. Res. Contr., vol.ll, p.6, pl.4, fig.4. 1961. Globigerinoides conglobatus (Brady), Andersen. La. Geol. Surv., Geol. Bull.35, pt.2, p.120, pl.27, fig.5. 1962. Globigerinoides conglobatus (Brady), Parker. Mioropahao., 701.8, 110.2, p.229, P103, fig.l‘S. Jones (1965) reports that Caribbean specimens of this species do not have the bulla structure which Parker (1962) has reported from Pacific specimens. Specimens from the western Gulf of Mexico frequently have the bullae structures. Bradshaw's (1959) Globigerinoides 22, (p.42, pl.7, figs.l6-l7)has been included in synonymy with Globigerinoides conglobatus by Jones (1965). Bradshaw (1959) distinguishes his Globigerinoides sp. from Globigerinoides rubra by the presence of four chambers in the final whorl of Globigerinoides sp. and by the smaller accessory apertures in G. sp. Specimens identical to Bradshaw‘s E? 52, were counted as E: ruber in this study because of specimens found having four chambers in the final whorl as well as having small accessory apertures which had the typical red coloration of G. ruber on the 127 initial chambers . _G_. conglobatus has been reported in the Pacific by Bradshaw (1959) as limited to warm water with the greatest abundance in the equatorial area. Brady (1884) records the limits of the species in the Atlantic as 40° N latitude to 35° 3 latitude. Be’ (1959) records the species in his "warm tolerant group." 1877. 1879. 1884. 1924. 1941. 1951. 1953. 1960. 1958. Globigerinoides quadrilobatus sacculifer (Brady) Plate 2, figure l6a-b Globigerina sacculifer Brady. Geol. Mag., new ser., sec.2, vol.4, no.12, p.535. Globigerina sacculifera Brady. Quart. Jour. Micr. Sci., new ser., vol.l9, p.287. - Globigerina sacculifera Brady. Rept. Voyage Challenger, Zool., vol.9, p.604, pl.80, figs.11-18; pl.82, fig.4. Globigerina sacculifera Brady, Cushman. U.S. Natl. Mus. Bull. 104, pl.2, p.21, figs.l-6. Globigerinoides sacculifera (Brady), Cushman. Am. Jour. Sci., vol.239, p.128, pl.3, fig.l. Globigerinoides sacculifera (Brady), Phleger and Parker, G.S.A. Mem.46, p.35, p1.19, figs.l7,l8. Globigerinoides sacculifera (Brady), Phleger 32 El. Rept. Swedish Deep-Sea EXped.,-vol.VII, no.1, p.16, pl.2, figs.5,6. Globigerinoides sacculifera (Brady), Phleger. Ecol. and Distr. of Recent Foram., p.223, pl.lo. Globigerinoides trilcba (Reuse), Drooger 33 El! Verhandl. der Koninklijke Neder. Akad. van'Wetenschappen, Afd. Natuur- 128 129 kunde, eerste reeks, deel XIII; Repts. of the Orinoco Shelf Exped., vol.l'V, p.83, p1.5, fig.8. 1958. Globigerinoides sacculifera (Brady), Drooger 3.17. 51. Verhandl. der Koninklijke Neder. Akad. van Wetenschappen, Afd. Naturkunde, eerste reeks, deel XIII; Repts. of the Orinoco Shelf Exped., vol.IV, p.83, p1.5, fig.9. 1959. Globigerinoides sacculifera (Brady), Be’. Micropaleo., vol.5, no.1, p.98, figs.l3-15. art—”u" " fl v 1959. Globigerinoides sacculifera (Brady), Bradshaw. Contr. Cushman Found. Foram. Res., vol.lO, pt.2, p.42, pl.7, figs.l4, 15, 18. 1960. Globigerina sacculifera Brady, Banner and Blow. Cushnmn Lab. Foram. Res., Contr., vol.ll, p.21, pl.4, figs.l,2. 1962. Globigerinoides quadrilobatus sacculifer (Brady), Parker. Micropaleo., vol.8, no.2, p.229, pl.3, figs.6-10. 1965. Sphaeroidinella dehiscens (Brady), he. Micropaleo., vol.ll, no.1, p.81, figs.4-8. Following Be"s (1965) conclusion that Sphaeroidinella dehiscens 1s a deep-water variant of Globigerinoides sacculifer, his figured lpeoimens of _S_. dehiscens are placed in synonymy here. The process involving acetate pools and electron micrographs which Be uses to arrive at his conclusion about 8. dehiscens is evidence that 130 other specimens of S. dehiscens figured in the existing literature cannot now be placed in synonymy with Globigerinoides sacculifer. Just as "Orbulina universa” has been shown by Bandy (1966) to be a reproductive or resting stage for a number of species of planktonic feraminifera, "Sphaeroidinella dehiscens" may represent the deepawater, thickened stage of other species as well as Globigerinoides sacculifer. E, triloba of authors has been included in.snyonymy here as B6 (1966) has shown this "species" to be a juvenile stage of Globigerinoides sacculifer without a sac. Much variability was observed in G. sacculifer, particularly in the size and configuration of the sac. This variation will be considered in a later section. G. sacculifer has been recorded from all of the world's oceans. Phleger (1960) reports that the species is common in middle- latitudes with the highest frequencies in the Gulf of Mexico. Brady (1884) reports the Atlantic distribution to be from.latitude 79° 20' N to latitude 46° 46' S. Bradshaw (1959) has reported the Pacific distribution of the species as most abundant between 40° N latitude and 20°N latitude. Coiling in this species is greater than 95 percent right in the western Gulf of Mexico. 1839. 1924. 1941. 1950. 1951. 1953. 1957. 1958. 1958. Globigerinoides ruber (D'Orbigny) Plate 2, figure 12a-c, 142-0. Globigerina rubra D'Orbigny. In de la Sagra, Hist. Phys. Pol. Nat. Cuba ”Fbraminiferes", p.82, vol.8, p1.4, figs.12-l4. G10bigerina rubra D'Orbigny, Cushman. U.S. Natl. Mus. Bull. 104, p.15, pl.3, rigs.4.7. Globigerinoides rubra (D'Orbigny), Cushman. Amer. Jour. Sci., vol.239, p.128, pl.3, fig.3. Globigerinoides cyclostcma (Galloway and'Wissler), Natland. GOSOAO Meme 43' P936, 131.10, f1g3.4&,b,c. Globigerinoides rubra (D'Orbigny), Phleger and Parker. G.S.A. Men. 46, p.35, p1.19, fig.lB. Globigerinoides rubra .(D'Orbigny), Phleger EEHEER Repts. Swedish Deep-Sea Exped., vol.VII, no.1, p.15, pl.2, figs.4-7. Globigerinoides rubra (D'Orbigny), Loeblich.gt_gl3 U.S. Natl. Mus. Bull.215, p.32, p1.4, fig.2a-c. Gldbigerinoides cyclostcma (Galloway and‘Wissler), Drooger et al. Verhandl. der Koninklijke Neder. Akad. van Wetenschappen, Afd., Natuurkunde, eerste reeks, Deel XXII; Repts. of the Orinoco Shelf Exped., vol.IV, p.82, p1.5, fig.7. Globigerinoides rubra (D'Orbigny), Drooger gt_gl, Verhandl. 131 132 der Koninklijke Neder. Akad. van wetenschappen Afd. Natuurkunde, eerste reeks, deel XXII; Repts. of the Orinoco Shelf Exped., vol.IV, p.83, p1.5, fig.lO. 1958. Globigerinoides rubra (D'Orbigny), Parker. Repts. Swedish Deep~Sea Exped., Vol.VIII, no.4, p.279, pl.6, fig.lZ. 1959. Globigerinoides rubra (D'Orbigny), Ba. Micropaleo., vol.5, no.1, p.98, pl.2, fig.16-17. 1959. G10bigerinoides rubra (D'Orbigny), Bradshaw. Contr. Cushman Found. Foram. Res., vol.lO, pt.2, p.42, pl.7, figs.12,l3. 1960. Globigerinoides rubra (D'Orbigny), Phleger. Ecol. and Distr. of Recent Foram., p.223, pl.lO. 1960. Globigerina rubra D‘Orbigny, Banner and Blow. Cushman Found. Foram. Res. Contr., tol.1l, p.19, pl.3, fig.8. 1961. Globigerinoides rubra (D'Orbigny), Andersen. La. Geol. Surv., Geol. Bull.35, pt.2, p.120, pl.27, fig.4a,b. 1962. Globigerinoides ruber (D'Orbigny), Parker. Micropaleo., vol.8, no.2, p.230, pl.3, fig.ll-l4. Specimens of Globigerinoides ruber encountered in.this study correspond only to Parker's (1962) groups 1 and 2. The 3rd group of g. ruber recognized bnyarker (1962) from Pacific samples corresponds to her Globigerinoides pyramidalis, van den Broeck, 133 which Parker described from Mediterranean samples (Parker, 1958). The latter type is characterized by a high conical structure and by small supplementary apertures. western Gulf of Mexico specimens of g, £322£_are characterized by large apertural openings and.a low spire. Jones (1965) reports the g. pyramidalis variety of this species from the Caribbean. Similarly, Drooger (1958) reports the same variety from the Orinoco area. Color variation was tabulated in this species as l. "colorless", 2. Colored (red) throughout and 3. colored red on the initial chambers only. In addition, many specimens have bullae covering the umbilical as well as the supplementary apertures. g. £3235.'33 the most abundant species in the area studied. The species is reported by Brady (1884) between latitude 49° N and latitude ss0 5 in the Atlantic, with the highest concentration in the tropical area. Phleger (1953) reports the highest frequencies for the species in the Gulf of Mexico. Bradshaw (1959) and Parker (1960) report the species throughout the tropical and temperate Pacific, With the greatest concentration in the equatorial waters. Genus Globoquadrina Finlay, 1947 Type species Globorotalia dehiscens Chapman, Parr and Collins, 1934 1826. 1839. 1898. 1901. 1901. 1941. 1951. 1953. Globoquadrina dutertrei (D'Orbigny) Plate 2, figure 9a-c Globigerina rotundata D'Orbigny. Ann. Sci., Nat. ser.l, vol.7, p.277, no.6. r“ Globigerina dutertrei D'Orbigny. In de la Sagra, Hist. -.-_- A.. Phys. Pol. Nat. cuba Foraminiferes, p.84, vol.8, p1.4, fig. m J. 19-21. Globigerina rotundata D'Orbigny, Fornasini. Pal. Italica, vol.4, p.208, fig.3. Globigerina eggeri Rhumbler. In Brandt Nordisches Plankton. Lief. no.1, no.14, p.19, fig.20. Globigerina subcretacea Lomnicki. Naturf. Ver. Berlin, BdJD (1900), p.17, pl.82, fig.lO. Globigerina conglomerata Schwager, Cushman. Amer. Jour. Sci. vol.239, p.128, pl.l, fig.3. Globigerina eggeri Rhumbler, Phleger, Parker. G.S.A. Mem.46, p.34, pl.19, fig.8,9. Globigerina eggeri Rhumbler, Phleger gt_£1. Repts. Swedish Deep-Sea Exped., vol.VII, no.1, p.12, pl.l, figs.11,12. 134 1958. 1958. 1959. 1959. 1960. 1960. 1962. 1963. 135 Globigerina eggeri Rhumbler, Drooger 33_313 Verhandl. der Kcninklijke Neder. Akad. van Netenschappen, Afd. Natuurkunde, eerste reeks, deel XXII; Repts. of the Orinoco Shelf Exped., vol.IV, p.84, p1.5, fig.1. Globigerina eggeri Rhumbler, Parker. Repts. Swedish Deep- Sea Exped., vol.VIII, no.4, p.277, p1.5, fig.7. Globigerina eggeri Rhumbler, B5. Micropaleo., vol.5, no.1, p.98, pl.2, figs.1-3. Globigerina eggeri Rhumbler, Bradshaw. Contr. Cushman Found. Fbram. Res., vol.10, pt.2, p.35, pl.6, figs.5,10. Globigerina eggeri Rhumbler, Phleger. Ecol. and Distr. of Recent Foram., p.223, pl.10. Globigerina rotundata D'Orbigny, Banner and Blow. Cuahman Found. Foram. Res. Contr., vol.ll, p.19, pl.2, fig.2. Globoquadrina dutertrei (D'Orbigny), Parker. Micropaleo., vol.8, no.2, p.242, pl.7,'rig.l-13;“pl.8, fig.l-4. Globigerina eggeri Rhumbler, Smith. Contr. Cushnan Found. Foram. Res., vol.l4, pt.1, p.1, pl.2, figs.8-ll. Globoquadrina dutertrei (D'Orbigny) was five to ten percent of most of the planktonic faunas examined in the course of this study. Twelve to thirty percent of the specimens of this species exhibited a considerable difference in size between the peniultimate and ultimate 136 chambers so that the ultimate chamber was diminutive. Specimens with a diminutive final chamber were evenly dispersed throughout the bathymetric profile in sediments deeper than one hundred and ten meters. Phleger (1990) has reported this species to be most abundant in low latitudes. In the North Atlantic, Phleger (1953) reports the species between 0° latitude and 60° N latitude. Bradshaw (1959) reports the species in the Pacific between 0° latitude and 45° N latitude, with hi! highest concentrations around 40° N latitude. Parker (1960) reports the species as widespread in the southeast Pacific. The apparent disparity in the temperature preference of this form, as reported in the published literature, is largely due to the taxonomic confusion that has existed between this species and Globigerina conglomerata, Globigerina eggeri, and Globigerina incompta, as well as to the apparent morphological intergrade between this species and Globigerina pachyderma, Smith (1963). Genus Globorotalia Cushman, 1927 Type species Pulvinulina menardii (D'Orbigny) var. tumida Brady, 1877 Globorotalia crassafcrmis (Galloway and sissler) Plate 1, figure 7a-c, 8a-c 1884. Pulvinulina orassa (D'Orbigny), Brady. (not Rotalia crassa, D'Orbigny). Rept. Voyage Challenger, Zool., vol.9, p.694, pl.103, figs.ll-13. its "_"-~T1" .7". 1927. Globigerina crassafcrmis Galloway and Wissler. Jour. Paleo., vol.1, p.41, pl.7, fig.lz. 1949. Globorotalia (Turborotalia) oceanica Cushman and Bermudez. Cushman Lab. reran. Res. Contr., vol.25, p.43, pl.8, fig.l3-15. 1951. Globorotalia punctulata .(D'Orbigny), Phleger and Parker. G.S.A. Mom. 46, p.36, pl.20, fig.3-7. 1953. Globorotalia punctulata (Fornasini), Phleger, Parker and Pierson. Swedish Deep-Sea Exped., Repts. vol.VII, fasc.l, p.20, p1.4, figs.8412. 1956. Globorotalia puncticulata (D'Orbigny), Bandy. U.S.G.S. Prof. Paper 274 G, p.194, pl.31, figs.la-c. 1959. Globorotalia punctulata (D'Orbigny), Be. Micropaleo., V01.5, 110.1, p998, p191, £138.9-11. 1961. Globorotalia (Truncorotalia) of. G. hirsuta (D'Orbigny), Andersen. La. Geol. Surv., Geol. Bull.35, pt.2, p.117, 137 138 pl.26, figs.2a-c. 1962. Globorotalia crassafcrmis (Galloway and Wissler), Parker. Globorotalia crassafcrmis was rare in the western Gulf of Mexico. Those specimens counted, however, did exhibit the typical secondary thickening of the test which is characteristic of the globorotalids. Jones (1965) records the rare occurrences of a closely related form, Globorotalia hirsuta (D'Orbigny), in the Caribbean area. Juvenile stages of g. hirsuta are in some cases nearlyiindistinguishable from Globorotalia crassafcrmis. However, no specimens, juvenile or adult, of _G_. hirsuta were encountered in this study. _G_. crassafcrmis is reported in the North Atlantic from 0° latitude to 54° 53' N latitude with greatest concentrations near the equator. Parker (1960) reports the species in concentrations south of latitude 40° 3 in the South Pacific. Bradshaw (1959) does not report the species in the north and equatorial Pacific. Be (1959) records _G_. crassafcrmis as a warm tolerant species. The species has been subdivided in the literature into variants based on the sharpness of the keel and the general outline of the test. These features are mnctions of the thickness of the secondary thickening of the test and are therefore not of taxonomic value . .. I“ '1' ‘. 1826. 1826. 1826. 1839. 1885. 1902. 1906. 1941. 1951. Globorotalia cultrata .(D'Orbigny) Plate 1, figures lla-c,-12a-c Rotalia (Rotalie) menardii D'Orbigny. Ann. Sci. Nat., ser.1, vol.7, p.273, no.26. Rotalia limbata D'Orbigny. Ann. Sci. Nat., ser.1, vol.7, p.274, no.30. Rotalia nitida D'Orbigny. Ann. Sci. Nat., ser.1, vol.7, p.274, no.3l. ‘ to. Rotalia (Rotalina) cultrata DfOrbigny. In de la Sagra, Hist. Phys. Pol. Nat. Guba "Fbraminiferes", p.76, vol.8, p1.5, figs.7-9. Rotalia menardii Parker, Jones and Brady. Ann. Mag. Nat. Hist., vol.16, ser.3, p.20, pl.3, fig.81. Rotalia limbata D'Orbigny, Fornasini. R. Accad. Sci. Inst., Bologna, Mom. Sci. Nat., ser.5, vol.10, p.56, fig.55. Rotalia nitida D'Orbigny, Fornasini. R. Accad. Sci. Inst., Bologna, Mom. Sci. Nat., ser.6, vol.3, p.66, pl.3, fig.4. Globorotalia menardii (D'Orbigny), Cushman. Amer. Jour. Sci., vol.239, p.128, pl.3, fig.2. G1dbcrotalia menardii (D'Orbigny), Phleger and Parker. G.S.A. Mem.46, p.36, pl.20, figs.1,2. 139 1953. 1959. 1959. 1960. 1960. 1960. 1960. 1960. 1961. 1961. 140 Globorotalia menardii (D'Orbigny), Phleger gt 21. Swedish Deep—Sea Exped., vol.VII, no.1, p.19, pl.3, fig.l,2,4,5. Globorotalia menardii (D'Orbigny), Be. Micropaleo., vol.5, no.1, p.98, pl.l, fig.l-3. Globorotalia menardii (D'Orbigny), Bradshaw. Contr. Cushman Found. Foram. Res., vol.10, pt.2, p.44, pl.8, fig.3,4. Globorotalia menardii (D'Orbigny), Phleger. Ecol. and a Distr. of Recent Foram., p.223, pl.lO. Rotalia limbata D'Orbigny, Banner and Blow. Cushnan Found. Fbram. Res. Contr., vol.ll, p.30, p1.5, fig.3. Rotalia nitida D'Orbigny, Banner and Blow. Cushman Feund. Foram. Res. Contr., vol.ll, p.33, pl.6, fig.3. Rotalia cultrata D'Orbigny, Banner and Blow. Cushman Found. Foram. Res. Contr., vol.ll, p.34, pl.6, fig.l. Rotalia menardii Parker, Jones, Brady, Banner and Blow. Cushman Found. Foram. Res. Contr., vol.ll, p.31, pl.6, fig.2. Globorotalia cultrata menardii (Parker, Jones,Brady), Andersen. La. Geol. Surv., Geol. Bull.35, pt.2, p.116, pl.25, figs.lOa-c. Globorotalia cultrata fimbriata (Brady), Andersen. La. Geol. Surv., Bull.35, pt.2, p.116, pl.26, figs.5a-c. 141 1962. Globorotalia cultrata D'Orbigny, Parker. Micropaleo., vol.8, no.2, p.235, p1.5, fig.3-5. Globorotalia cultrata has been subdivided by various authors by the presence or absence of the crystalline, secondary wall thickening. Evidence is presented in this study to show that this feature is a function of the individual Specimen's habitat and thus has no place in taxonomic considerations. The presence of a diminutive last chamber was common in this species in samples deeper than sixty meters. Gldborotalia cultrata is generally regarded as a warm water, low latitude form. It is reported by Bradshaw (1959) and Parker (1960) between latitude 40° N and latitude 40° S in the Pacific, with concentrations in the equatorial regions. Brady (1884) gives the Atlantic distribution as latitude 55° 11' N to latitude 36° S. Phleger (1953) reports the highest percentages of the species in the Gulf of Mexico. 1839. 1924. 1951. 1953. 1958. 1958. 1959. 1961. Globorotalia inflata (D'Orbigny) Plate 1, figure 6a-c Globigerina inflata D'Orbigny. In Barker-webb and Berthelot, Hist. Nat. Iles Canaries "Foraminiferes", vol.2, pt.2, Zool., p.134, pL2, figs.7-9. " Globigerina inflata D'Orbigny, Cushman. U.S. Natl. Mus. Bull. 104, p.12, pl.3, figs.l,2,3. . Ps»_1ll b~..!.1 3 Globigerina inflata D'Orbigny, Phleger and Parker. G.S.A. Mem.46, p.34, pl.19, figs.lO,1l. Globigerina inflata D'Orbigny, Phleger at El! Repts. Swedish Deep-Sea Exped., vol.VII, no.1, p.13, pl.l, figs.15,16. Globigerina infhita D'Orbigny, Drooger gt_gl. Verhandl. der Koninklijke Neder. Akad. van'Wetenschappen, Afd. Natuurkunde, eerste reeks, deel XXII; Repts. of the Orinoco Shelf Exped., vol.IV, p.84, p1.5, fig.2. Globigerina inflata D'Orbigny, Parker. Repts. Swedish Deep-Sea Exped., vol.VIII, no.4, p.277, pl.6, figs.3. Globigerina inflata D'Orbigny, B6. Micropaleo., vol.5, no.1, p.98, pl.1, figs.12-l4. Globigerina inflata D'Orbigny, Bradshaw. Contr., Cushman Found. Fbram. Res., vol.10, pt.2, p.36, pl.6, fig.16,l7,18. Globorotalia (Turborotalia) sp. Andersen. La. Geol. Surv., Geol. Bull.35, pt.2, p.118, pl.26, fig.la-c. 142 143 1962. Globorotalia inflata E'Orbigny, Parker. Micropaleo. vol.8, no.2, p.236, p1.5, fig.6-9. Parker (1962) has placed this species in the Genus Globorotalia because it lacks well-developed spines. The species has been similarly placed in the Genus Globorotalia in this study. Specimens of Globorotalia inflata in the area studied are generally smaller in overall size (average .4mm.) than.specimens of the same species from the Atlantic and Pacific (average .8mm.). I; 9"- '1.“ I4 1 ’ _#_ Unlike most of the species of Globorotalia, G. inflata did not exhibit the secondary thickening of the test wall. The species is rare in the western Gulf of Mexico. Parker (1954) reports a similar scarcity of the species in the eastern Gulf of Mexico. Jones (1965) does not report the species from the Caribbean area. However, Phleger (1950) reports it as abundant in middle latitudes. B5'(1959) lists the species in.his "cold tolerant" group. Parker (1960) and Bradshaw (1959) have reported scattered occurrences of the species in the north and south Pacific around latitude 40° S and latitude 40° N respectively with no reported occurrences in the equatorial region. 1882. 1884. 1929. 1950. 1951. 1953. 1957. 1959. 1961. 1962. Globorotalia scitula (Brady) Plate 1, figure 2a-c Pulvinulina scitula Brady. Roy. Soc. Edinburgh, Proc., vol.ll, (1880-82), no.111, p.716. Pulvinulina patagonia D'Orbigny, Brady. Rept. Voyage Challenger Zool., vol.9, p.693, pl.103, fig.7. _1 1. Inn-Q- Pulvinulina patagonia (D'Orbigny), Rhumbler. Nordische d Plankton-Fbraminiferen Zool., tell 7, p.13, figs.4,5. Globorotalia scitula (Brady),‘Wiseman et 21, Geol. Assoc. Proc., vol.61, pt;i, p.69, pl.3, fig.lla-c. Globorotalia scitula (Brady), Phleger and Parker. G.S.A. Mem.46, p.36, pl.20, figs.8,9. Globorotalia scitula (Brady), Phleger gt_313 Repts. Swedish Deep-Sea Exped., vol.VII, no.1, p.21, p1.4, fig.13,l4. Globorotalia scitula (Brady), Loeblich et a1. U.S. Natl. Mus. Bull. 215, p.120, pl.29, figs.lla-lZc. Globorotalia scitula (Brady), Bradshaw. Contr. Cushman Found. Foram. Res., vol.10, pt.2, p.44, pl.8, figs.5,6. Pulvinulina scitula Brady, Banner and Blow. Cushman Found. Foram. Res. Contr., vol.ll, p.27, p1.5, fig.5. Globorotalia scitula (Brady), Parker. Micropaleo., vol.8, 144 145 no.2, p.238, pl.6, fig.4-6. Parker (1962) has reported some specimens of Globorotalia scitula with spines from.the Pacific. Only smoothawalled forms 'were encountered in.this study. The species was rare in.the area studied and did not exhibit the secondary thickening of the test wall common in other species of Globorotalia from the same area. Jones (1965) reported the species as rare in the Caribbean area. Brady (1884) has reported the Atlantic distribution as latitude 60° N to latitude 46° 8. In the Pacific it is reported by Bradshaw (1959) in very scattered areas from.the equatorial region to latitude 45° N and by Parker (1960) south of latitude 40° S. 1839. 1929. 1941. 1950. 1951. 1953. 1957. 1959. Globorotalia truncatulinoides (D'Orbigny) Plate 1, figures 3a-c, 4a~c Rotalina truncatulinoides D'Orbigny. In Barker4webb and Berthelot, Hist. Nat. Iles Canaries "Foraminiferes", vol.2, pt.2, p.123, pl.2, fig.25, 26, 27. Pulvinulina truncatulinoides (D'Orbigny), Rhumbler Nordische Planktoonoraminifer n Zool., tail 7, p.17, figs.l6-18. Globorotalia truncatulinoides (D'Orbigny), Cushman. Amer. Jour. Sci., vol.239, p.128,‘pl.4, fig.l. Globorotalia truncatulinoides (D'Orbigny), Wiseman st 51. Geol. Assoc. Proc., vol.61, pt.1, p.66, pl.2, fig.7a-c. Globorotalia truncatulinoides (D'Orbigny), Phleger, Parker. G.S.A. Mem.46, p.36, figs.lO-l3. Globorotalia truncatulinoides (D'Orbigny), Phleger gt_213 Swedish Deep-Sea Exped. Rept., vol.VII, pt.1, p.22, p1.4, figs.l7,l8. Globorotalia truncatulinoides (D’Orbigny), Loeblich gE_313 U.S. Natl. Mus. Bull.215, p.4l,'pl.lo, figs.3a-c. Globorotalia truncatulinoides. (D'Orbigny), Bé. Micropaleo. vol.5, no.1, p.98, p1.1, figs.5-7. 146 147 1959. Globorotalia truncatulinoides (D'Orbigny), Bradshaw. Contr. Cushman Found. Fbram. Res., vol.10, pt.2, p.44, pl.8, fig.7,8. 1960. Globorotalia truncatulinoides (D'Orbigny), Phleger. Ecol. and Distr. of Recent Foram., p.243, pl.10. 1961. Globorotalia (Truncorotalia) truncatulinoides (D'Orbigny), Andersen. La.‘Geol. Surv.,Geol. Bull.35, pt.2, p.117, pl.26, fig.3a-c. 1962. Globorotalia truncatulinoides (D'Orbigny), Parker. Micropaleo., vol.8, no.2, p.239, pl.6, fig.7. In addition to the secondary thickening of the test, specimens of Globorotalia truncatulinoides exhibit variation in the size of the umbilical opening and the size of the final chamber. Populations of g. truncatulinoides counted in this study are over ninety percent right coiling. Bradshaw (1959) and Parker (1960) have recorded the Pacific distribution of this species as two disjunct, narrow east-west belts at latitude 30° N and latitude 300 3. Be’ (1959) records the highest Atlantic concentration of this species in the Sargasso Sea region. Brady (1884) reports the species in the Atlantic between latitude 79° N and 46° 8. Phleger (1953) reports the highest frequen- cies of the species in the Gulf of Mexico. wt: . 1877. 1884. 1941. 1950. 1951. 1953. 1957. 1959. 1960. Globorotalia tumida (Brady) Plate 1, figures 9apc, lOa-c Pulvinulina menardii (D'Orbigny) var. tumida Brady. Geol. Mag., ner ser. dec.2, vol.4, no.12, p.535. Pulvinulina tumida Brady. Rept. VOyage Challenger, Zool., vol.9, p.692, pl.lOS, figs.4-6. Globorotalia tumida (Brady), Cushman. Amer. Jour. Sci., fl”-.. . ‘s‘ an ' . £3 vol.259, p.128, pl.3, fig.3. Globorotalia tumida (Brady),'Wiseman et El: Geol. Assoc. Proc., vol.61, pt.1, p.69, pl.3, figs.2a-c. Globorotalia tumida (Brady), Phleger and Parker. G.S.A. Mem.46, p.36, pl.20, fig.l4.15. Globorotalia tumida (Brady), Phleger et a}: Repts. Swedish Deep-Sea Exped., vol.7, no.1, p.22, pl.3, fig.5. 6,7,8,lO.11. Globorotalia tumida (Brady), Loeblich.gt_3g, U.S. Natl. mus. Bull.215, p.41, pl.10. fig.2a-c. Globorotalia tumida (Brady), Bradshaw. Contr. Cushman Found. Foram. Res., vol.10, pt.2, p.47, pl.8, fig.9-l3. Globorotalia tumida (Brady), Phleger. Ecol. and Distr. Recent Foram., p.223, pl.10. 148 149 1960. Pulvinulina.menardii (D'Orbigny) var. tumida Banner and Blow. Cushman Found. Fbram. Res. Contr., vol.ll, p.26, p1.5, fig.l. 1961. Gldborotalia tumida (Brady), Andersen. La. Geol. Surv., Geol. Bull.35, pt.2, p.116, pl.26, figs.4a-c. 1962. Globorotalia tumida (Brady), Parker. Micropaleo., vol.8, no.2, p.239, pl.6, fig.8-10. Most of the specimens of Globorotalia tumida counted in the western Gulf of Mexico have a secondarily thickened test. Jones (1885) records this species as rare in.the Caribbean area. In.the present study the species was found to be in significant percentages only in some of the deeper samples. Bradshaw (1959) reports concentrations of this species in the equatorial Pacific, with smaller percentages up to latitude 25° N in the south Pacific. It is reported by Parker (1962) from latitude 20° N. Brady (1884) records the species from latitude 38° N to latitude 35° 3 in the Atlantic. 1839. 1876. 1884. 1924. 1929. 1957. 1958. 1959. Genus Hastigerina Thomson, 1876 Type species Hastigerina murrayi Thomson, 1876 Hastigerina pelagica (D'Orbigny) Plate 2, figure l7a,b Nonionina pelagica D'Orbigny. Voyage Amer. Merid. "Foraminiferes", vol.5, pt.5, p.27, pl.3, figs.13-14. Hastigerina murrayi Thomson. Roy. Soc. London, Proc., vol.24, p.534, pl.22,23. tn Hastigerina pelagica. (D'Orbigny), Brady. Rept. beage Challenger, Zool., vol.é, p.613,~p1.83, figs.l-B. Hastigerina pelagica (D'Orbigny), Cushman. U.S. Natl. Mus. Bu11.104, p.33, pl.6, figs.l-B. Hastigerina pelagica (D'Orbigny), Rhumbler. Nordische Plankton-Foraminiferen Zool., tail 7, p.28, fig.3l. Hastigerina murrayi Thomson, Loeblich gt El! U.S. Natl. mus. Bull.216, p.29, pl.3, figs.l-3. Hastigerina pelagica (D'Orbigny), Parker. Repts. Swedish Deep-Sea Exped., vol.VIII, no.4, p.280, pl.6, fig.15. Hastigerina pelagica (D'Orbigny), B6. Micropaleo., vol.5, no.1, p.98, pl.2, fig.21,22. 150 151 1959. Hastigerinella rhumbleri Galloway, Be; Micropaleo., vol.5, no.1, p.98, pl.2, fig.23. 1959. Hastigerina pelagica (D'Orbigny), Bradshaw. Contr. Cushman Fbund. Fbram. Res., vol.10, pt.2, p.47, pl.8, figs.l4,15. 1960. Hastigerina pelagica (D'Orbigny), Banner and Blow, Micropaleo., vol.6, no.1, p.20, fig.l. 1961. Hastigerina pelagica (D'Orbigny), Andersen. La. Geol. Surv., Geol. Bull.35, pt.2, pl.28, figs.3a,b. 1962. Hastigerina pelagica (D'Orbigny), Parker. Micropaleo.. vol.8, no.2, p.228. Jones (1965) and Parker (1962) both note the disparity between the high number of specimens of Hastigerina pelagica in the plankton tows and the low number found in the bottom sediments of the Caribbean and Pacific regions respectively. These authors have suggested that the specimens hawe been destroyed by abrasion and/er solution in bottom sediments due to the fragility of the test. Specimens encountered in.this study'were often broken, but no solution of the test was evident. Jones (1985) has included Be's (1959) figure of Hastigerinella rhumbleri, Galloway, in synonymy with Globigerinella adamsi; however, the former species lacks the characteristic pointed, distal terminations on the ultimate and peniultimate chambers as illustrated by Parker (1962). A complete gradation was evident between the elongate chambered 152 "Hastigerinella rhumbleri" form and the compressed chambered ”Hastigerina pelagica". Thus, 11. rhumbleri is included in synonymy here with _I_i_. pelagica. Parker (1962) and Bradshaw (1959) report the species from the Pacific between latitude 40° N and latitude 50° 8 with the highest concentratiom around latitude 40° S and latitude 30° N. It has been reported in the Atlantic by Be (1959) as a warm tolerant species with highest concentrations south of latitude 40° N . Genus Orbulina D’Orbigny, 1859 Type species Orbulina universe D'Orbigny, 1839 Orbulina universe D'Orbigny Plate 2, figure 13a,b 1839. "Orbulina universe" D'Orbigny. In de la Sagra Hist. Phys. Pol. Nat. Cuba, "Fbraminiferes", p.3, vol.8, pl.l, fig.1. Bandy (1966) has illustrated a number of broken specimens of V- "Orbulina universe" with juvenile specimens of Globigerinoides sacculifera, Gldbigerina bulloides and Globigerinoides conglobatus as internal ontogenetic stages. Because this seems to be conclusive evidence of polyphyly in Orbulina, no snypnymy is presented here for lack of a technique of distinguishing the various species of Orbulina without internal juvenile stages. Orbulina spp. has been considered in this study as a single species. Only two percent of the specimens examined in this study contained an internal globigerine chamber (see plate 2, fig.lfia). The thickness of the Orbulina test wall varied greatly, but the distribution of thick and.thin§walled specimens appears to be random with respect to depth. 153 Genus Pulleniatina Cushman, 1927 Type species Pulleniatina obliquiloculata Parker and Jones, 1865 1862. 1865. 1924. 1941. 1950. 1951. 1953. 1957. Pulleniatina obliquiloculata (Parker and Jones) Plate 1, figure 5a-c Pullenia obliquiloculata Parker and Jones, In Carpenter, Introd. Foram., p.183. Pullenia sphaeroides (D'Orbigny) var. obliquiloculata Parker and Jones. Roy. Soc. London, Philos. Trans., vol. 155, p.365, pl.19, fig.4a-b. Pullenia obliquiloculata Parker and Jones, Cushman. U.S. Natl. Mus. Bu11.104, p.43, pl.8, fig.10a,b. Pulleniatina obliquiloculata (Parker and Jones), Cushman. Amer. Jour. Sci., vol.239, p.128, p1.4, fig.3. Pulleniatina obliquiloculata (Parker and Jones), Wiseman.gt_ El! Geol. Assoc. Proc., vol.61, pt.1, p.69, pl.3, fig.7. Pulleniatina obliquiloculata (Parker and Jones), Phleger and Parker. G.S.A. Mem.46, p.35, pl.19, figs.19,20. Pulleniatina obliquiloculata (Parker and Jones), Phleger 3: El! Repts. Swedish Deep-Sea Exped., vol.VII, no.1, p.17, pl.2, fig.16-l8. Pulleniatina obligueloculata (Parker and Jones), Loeblich gt_213 U.S. Natl. Mus. Bull.215, p.33, p1.4, figs.5e5. 154 155 1959. Pulleniatina obliquiloculata (Parker and Jones), B6} Micropaleo., vol.5, no.1, p.98, pl.2, fig.4-6. 1959. Pulleniatina obliquiloculata (Parker and Jones), Bradshaw. Contr. Cushman Found. Foram, Res., vol.10, pt.2, p.49, pl.8, fig.19, 20. 1960. Pulleniatina obliquiloculata (Parker and Jones), Phleger. Ecol. and Distr. Recent Fbrame, p.223, pl.10. 1960. Pullenia spaheroides (D'Orbigny), var. obliquiloculata Banner and Blow; Cushman Found. Foram. Res. Contr., vol.ll, p.25, pl.7, fig.4. 1962. Pulleniatina obliquiloculata (Parker and Jones), Parker. Micropaleo., vol.8, no.2, p.234, p1.4, figs.l3-16, 19, 22. Parker (1962) has reported live specimens of Pulleniatina obliquiloculata from Pacific plankton tows with thin smooth tests, whereas specimens taken from.Pacific sediments have a thick, highly polished test. Populations of the species in the area studied were very uniform.in the foregoing respect being almost totally thick- ‘walled and polished in appearance. Jones (1965) reports the species as rare in the Caribbean sediments and waters, whereas it composes a considerable percentage of the fauna in.most of the samples taken from the eastern (Parker, 1954) and western Gulf of Mexico. Drooger (1958) reports Pulleniatina obliquiloculata as rare in sediments from the Orinoco Shelf area. The Atlantic distribution is reported by Phleger (1953) as highest east of Guba and in the Gulf 156 of Mexico. Be’ reports the species as cold tolerant and scattered in the Atlantic, increasing toward the northern Gulf Stream off North America. Phleger (1960) has characterized the species as a low latitude form. In the Pacific Bradshaw (1959) and Parker (1960) report the species from latitude 40° N to latitude 10° S with highest concentrations in the equatorial region. 1839. 1924. 1929. 1941. 1953. 1957. 1959. 1959. Incertae Familiae Genus Candeina D'Orbigny, 1839 Type species Candeina nitida D'Orbigny, 1839 Candeina nitida D'Orbigny Candeina nitida D'Orbigny. In de la Sagra, Hist. Phys. Pol. Nat. cubs Foraminiferes, p.108, pl.2, fig.27, 28. Candeina nitida D'Orbigny, Cushman. U.S. Natl. Mus. Bull. f 104, p.34, p1.5, fig.l. Iii-n Candeina nitida iD'Orbigny, Rhumbler. Nordische Plankton- Formniniferen, Zool., teil VII, p.35, fig.35a-c. Candeina nitida D'Orbigny, Cushman. Amer. Jour. Sci., vol.239, no.2, pl.2, fig.1. Candeina nitida D'Orbigny, Phleger, Parker and Pierson. Repts. Swedish Deep-Sea Exped., vol.VII, no.1, p.18, pl.2, fig.22, 23. Candeina nitida D'Orbigny, Bolli, Loeblich and Tappan. U.S. Natl. Mus. Bull.215, p.35, pl.6, fig.10a-11. Candeina nitida D'Orbigny, B6. Micropaleo., vol.5,- no.l, pl.2, fig.19,20. Candeina nitida D'Orbigny, Bradshaw. Contr. Cushman Found. Foram. Res., vol.X, p.32, pl.7, fig.19. 157 158 1961. Candeina nitida D'Orbigny, Andersen. La. Dept. of Conserv., Geol. Surv., Geol. Bu11.55, pt.2, p.122, pl.27, fig.6. 1962. Candeina nitida D'Orbigny, Parker. Micropaleo., vol.8, no.2, p.253, pl.8, fig.27-30. This easily recognized species was rare in the western Gulf of Mexico. Parker (1962) has placed the Genus Candeina in Incertae Fumiliae because it lacks the coarse perforations of spinose wall which is characteristic of the globigerines. Bolli, Loeblich and Tappan(1957) report that Candeina nitida passes through a "Gldbigerina" (single aperture) stage, followed by a "Globigerinoides" (multiple aperture) stage in its ontogenetic development. Specimens dissected in the present study were entirely smoothawalled at all stages of development. In view of the variability in the number of apertures in planktonic forms, classifications and phylogenies based on this character seem.unwarrented. Candeina nitida has been reported from.the Pacific by Bradshaw (1959) between latitude 30° 3 and latitude 40° N. Cushman (1924) reports the species to be concentrated in the Caribbean area of the Atlantic; however, it has been reported in small percentages in the north Atlantic as far as latitude 55° N. Bibliography Bandy, Orville L., 1960. Concepts of foraminiferal ecology. A.A.P.G. Bulletin, v.44, no.12, p.1921-1932. Bandy, Orville L., 1954. Distribution of some shallowuwater foraminifera in the Gulf of Mexico. U.S. Geol. Surv. Prof. Paper 254-F. Bandy, Orville L., 1956. Ecology of foraminifera in northeastern Gulf of Mexico. U.S. Geol. Surv. Prof. Paper 274-G. 3 Bandy, Orville L., 1964. Foraminiferal biofacies in sediments of Gulf 'F—‘"-'—‘T 15 of Batabano, Cuba and their geologic significance. Bull. Amer. Assoc. Pet. 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Contr., v.XIV, pt.l. Smith, A. Barrett, 1964. Living planktonic foraminifera collected along an eastawest traverse in the north Pacific. Contr., Cushman Found., v.XV, pt.4. PLATE l , “T/ u; 2. 26 2: 999999 weGPt? Plate 1 All figures X35 All figures view (a,c) side view; view (b) edge view 1. Candeina nitida d'Orbigny 2. Globorotalia scitula (Brady) 3, 4. Globorotalia truncatulinoides (d'Orbigny) fi g.3. Normal specimen fig.4. Specimen with secondary thickening 5. Pulleniatina obliquiloculata (Parker and Jones) 6. Globorotalia inflata (d'Orbigny) 7,8. Globorotalia crassaformis Cushman fig.7, Normal specimen fig.8. Specimen with secondary thickening 9,10. Globorotalia tumida (Brady) fig.9. Normal specimen . fig.10. Specimen with secondary thickening 11, 12. Globorotalia cultrata (d'Orbigny) fig.ll. Normal specimen fig.lZ, Specimen with secondary thickening 168 cit 3 89 6938299923 v® a ® '- eeeeéb K3.) lc 2: 3: ‘c 5: 6c. 7: as A?“ CD . , ' a. C. fie 4' "‘ as "0 BI 95 9: IO. IOB no: Plate 2 All figures X35 All figures view (a,c) side view; view (b) edge view except figures 13, 16, 17, 18 1,2. Globigerinita glutinata Bronniman fig.1. Specimen with umbilical bulla; fig.2. Specimen without bulla 3. Globigerina rubescens Hofker 4. Globigerinita humilis (Brady) Figure showing modified final chamber 5. Globigerina pachyderma (Ehrenberg) 6. Globigerinita uvula (Ehrenberg) 7,8. Globigerina digitata Brady fig.7. Specimen with umbilical bulla; fig.8. Specimen without bulla. 9. Globoquadrina dutertrei (D'Orbigny) 10. Globigerina bulloides (D'Orbigny) 11. Globigerinoides conglobatus (Brady) 12,14. Globigerinoides ruber (D'Orbigny) fig.12. Specimen with bullae covering acessory apertures fig.l4. Specimen without bullae 13. Orbulina universe (D'Orbigny) fig.l3. A broken specimen showing internal "globigerine" juvenile stage 15. Globigerinella siphonifera (D'Orbigny) 16. Globigerinoides quadrilobatus sacculifer (Brady) a,b edge views: Specimen with skewed multiple pointed sac 170 171 17. Hastigerina pelagica (D'Orbigny) a. edge view; b. side view 18. "Sphaeroidinella dehiscens" Views of E, sacculifer? showing thick secondary calcite crust PLA TE 3 6b mg" l7 2 Plate 3 All figures X55 All figures view (a,c) side views; view (b) edge view except fig.3 1. Globigerina rubescens Hofker 2. Globigerinita uvula (Ehrenberg) 3,4. Globigerinita glutinata Bronniman 3a,b side views; 3c edge view fig.3 Specimen with umbilical bulla fig.4 Specimen.without bulla 5,6. Globigerina digitata Brady fig.5. Specimen with umbilical bulla fig.6. Specimen without bulla 7. Globigerinita humilis (Brady) Specimen with modified final chamber 173