DISTRIBUTION OF THE RADIMELLA CONFRAGOSA GROUP … Den Bold... · C + 1- Tubara C Miles 0 200 400 600 " 1 I I I ) \ 0 400 600 Kilometers " TEXT-FIG. 1-Fossil and Recent distribution

$Page 1: DISTRIBUTION OF THE RADIMELLA CONFRAGOSA GROUP … Den Bold... · C + 1- Tubara C Miles 0 200 400 600 " 1 I I I ) \ 0 400 600 Kilometers " TEXT-FIG. 1-Fossil and Recent distribution$
JOURNAL OF PALEONTOLOGY, V. 49, No. 4, P. 692-701, 2 PLS., 3 TEXT-FIGS., JULY 1975 Copyright @ 1975, The Society of Economic Paleontologists and Mineralogists

DISTRIBUTION OF THE RADIMELLA CONFRAGOSA GROUP

(OSTRACODA, HEMICYTHERINAE) IN THE LATE NEOGENE OF THE CARIBBEAN

W. A. VAN DEN BOLD Louisiana State University, Baton Rouge, 70803

ABSTRACT-Five different forms are recognized within the shallow marine, subtropical Radimella confragosa group, four are carried in open nomenclature. Radimella confragosa (Edwards), Radimella confragosa form A, and Radimella sp. 1 first appear at about the Miocene-Pliocene boundary (base N 18 or uppermost N 17). Radimella confragosa is the only species of this group occurring over the whole area, disappearing during the Pleistocene. Fossil and Holocene distribution of Radimella confragosa form A appears to be confined to the Greater Antilles (except western Cuba), part of the Bahamas and the northern Lesser Antilles. Radimella sp. 1 appears to be confined to early Pliocene sediments of the Caribbean south shores. Radimella sp. 2 makes its appearance in the latest Pliocene or Pleistocene; it has not been found in northern South America and its recent distribution is in a belt from Panama, along Central America, following the Antilles arc to St. Lucia. Radimella sp. 3 is only known from Holocene deposits in a belt from Panama along the coast of South America, the Antillean arc and the Florida peninsula. Some of these restricted distributions are thought to be the result of differential temperature tolerance of the different forms.

INTRODUCTION

EMICYTHERE confragosa Edwards has been H shifted from one genus of the Hemi- cytherinae to another (Aurila, Mutilus) until Pokorn' (1969) described the new genus Radimella, in which he specifically included this species. It has also been noticed that

probably more than one species was included in this particular group, which has widespread distribution in the Caribbean; hence the use of the name Radimella ex gr. confragosa (Edwards) for species from Pliocene to Recent in this area. Up to the present not sufficient material had been studied from different areas to allow a reliable separation into different

species, but it was suspected that some of them might have a more restricted geographic or stratigraphic range and that these restric- tions may be the result of differences in temperature tolerance of the various forms.

Representative material has been deposited in the H. V. Howe Collection at the Museum of Geoscience, Louisiana State University, Baton

Rouge. DISTRIBUTION

The occurrence is listed by area, formation and age under each of the five different forms recognized within this group. Some of the formations are assigned slightly different

ages by different authors. These assignments have been brought up to date, where possible,

by referring to the recent literature on planktonic foraminiferal zonations (e.g. Blow, 1969; Lamb & Beard, 1972). In some cases the evidence is not conclusive and these age assignments have been indicated with a question mark, in others the age assignment is based on unpublished information, e.g., for northern Colombia (B. W. Bordine, Ph.D. dissertation, Louisiana State University, 1973), Costa Rica (G. Taylor, Ph.D. dissertation, in preparation, Louisiana State University) or Hispafiola and Cuba (van den Bold, personal observ.). The stratigraphy of the Neogene of the Caribbean is tabulated in van den Bold (1972b, tables 4 and 5).

Typical specimens of Radimella confragosa sensu stricto are found over the whole Carib- bean region and the southeastern United States from Virginia to Trinidad and from Mexico to Puerto Rico in Pliocene and some Pleistocene sediments (Text-fig. 1). Holocene forms re- ported under this name are now assigned to either Radimella confragosa form A, Radimella sp. 2, or Radimella sp. 3. Only on the north coast of Jamaica have some specimens of R. confragosa been found in Holocene deposits, but these may be derived from sediments of the Coastal Group of Formations exposed in the vicinity.

Radimella confragosa form A appears to be restricted to an area around the Greater Antilles. It occurs with R. confragosa sensu

692

LATE NEOGENE OSTRACODA 693

/ Waccamaw C e

00" -- 80 Duplin C

SC R. confragosa

(Edwards)

AR . confragosa forma A -

1 R. sp. 1

-30" aloosahatchee C + 2 R, sp. 2

" 'hoc .a!\\heeC

R. sp. 3

. ...ll... no Rodimelo found

Joimonitas 2 ? Matanzas C + 2 Moo C + A

200 Conimar C

La Cuz C+A GuraboC+A --20"

, • •.

Agueguexqui C / Hrbour Vie A Morne Delmar C +A Ponce C +A

S? Manchioneal A + 2 Las Salinas C +A ? ? Bowden C +A

, El Veral C + 1 Cbgua C +

.-0 - "Rio Banana" Pleist 2

Chorrera C Springv C +1

North boundory of Radimello 1 "Rio Banana" Plioc. C + 1- Tubara C

Miles 0 200 400 600 "

1 I

I I ) \ 0 400 600

" Kilometers

TEXT-FIG. 1-Fossil and Recent distribution of species of Radimella in the Caribbean.

stricto in Pliocene sediments, and in the Pleisto- cene without the latter. Holocene specimens have been found off Jamaica and in the Ba- hamas.

Radimella sp. 1 appears to be restricted to the lower part of the Pliocene in Venezuela and Costa Rica. It seems possible that this form disappeared due to lowering of. temperatures in the late Pliocene. It has not been found in northern Colombia, where only R. confragosa occurs and it is speculated that this may be caused by cold upwellings along this coast in the early Pliocene.

Radimella sp. 2 appears to be confined to the Pleistocene and Holocene (possibly also latest Pliocene) over most of the area. Its appearance in the area at a time of lowering temperatures and the fact that its present distribution suggests migration towards the south from a northern area, gives rise to the supposition that the distribution of this species

is governed by relatively lower temperatures than normal for the Radimella confragosa group, except the nominal species itself, which occurs over the whole area.

Radimnella sp. 3 is only known from Holo- cene deposits in a belt along the northern coast of South America, along the arc of the Antilles and up the Florida peninsula, thereby suggesting a dispersal from a southerly direction. It has not been found, so far, along the Central American coast except in Panama.

ORNAMENTATION

When Pokorny' introduced the genus Radi-

mella he indicated two Formenkreise in the Holocene Galapagos material that he was

studying; the R. dictyon group (Text-fig. 3f), in which the dorsal ridge lies about flush with the posterior part of the dorsal margin, and the R. ponderosa group, (Text-fig. 3g), in

694 W. A. VAN DEN BOLD

-i

a 0 0 0 0 0 0 0

cp 0 0 0 + - O 0

dc 0 0 - 0 0 0

pd - - + + v

DM A0 0 0 0 0

ACAO + + ++ + +

PCA a aI r a r a r

a 0 0 0 0 0 0 0

avm 0 0 0 e 0 0 0

av 0 0 0 E 0 0 E

VC 0 0 0 8 0 8 8

cp 0 0 0 + 0 0

pd- - + + V

d #/ K / # # //f

ad 2-3 3 5 5 4 6 3-5

ac 0 0 0 0 0o- +

A bend S

buckled

- convex

s sinuate

0 normal

+ accentuated

3 number of secondary meshes

a angular r rounded

/ parallel DM

/// flush with DM

- reduced

9 split

V depressed < diverging

TEXT-FIG. 2-Comparison of 14 selected features of different species of Radimella; for explanation of terms, see text. DM, dorsal margin; A CA, anterior cardinal angle; PCA, posterior cardinal angle.

which the dorsal ridge lies below and parallel to the posterodorsal margin. The pattern of reticulation in both groups is almost identical, but with minor variations, and the same basic pattern is found in the Radimella confragosa group, also with minor variations among the different representatives. Two groups, similar to PokornG's Formenkreise are recognized;

one, in which the dorsal margin is flush with the dorsal ridge (Radimella confragosa, Radi- mella sp. 3) or in which the dorsal ridge diverges slightly posteriorly from the margin and projects over it (Radimella confragosa form A), similar to what regularly occurs in immature molts of R. confragosa and Radi- mella sp. 3. The other group shows a


similarity to the R. ponderosa group, and has the dorsal ridge below and parallel to the dorsal margin (Radimella sp. 1 and Radimella sp. 2).

Based on the shape of the dorsal contour of the left valve, three groups may be distinguished. The first has a slightly bent dorsal margin (R. confragosa and Radimella sp. 2), or the dorsal margin is even somewhat buckled (R. confragosa form A); the second has a regularly convex dorsal margin (Radi- mella sp. 1) and in the third (Radimella sp. 3) the dorsal margin is sinuate due to a stronger projection of the anterior cardinal corner.

Some definite areas of the reticulation stand out in the R. confragosa group, and, in fact, in all species of Radimella known.

Pokorn)'s (1968) system of letter indication for these areas is here modified to adapt better to the principal features of the Carib- bean group. The center of the reticulation pattern is formed by a central mesh (c), just behind the attachment of the adductor muscles; it is well marked in all variants, also in the two groups from the Galapagos islands. It is usually rounded, seldom angular and most often almost circular (Text-fig. 3e). The other areas are enumerated from the anterior cardinal angle in a clockwise direction; a: anterior (= Pokorn)'s "Pre-ocular") between the anterior extension of the dorsal ridge and the vertical ridge connecting it to the eye-spot; adm: in front of the center, between upper and middle one of the three median ridges; avm: between middle and lower median ridge; av: anteroventral, below the lower median ridge; vc: directly below the central mesh; cp: obliquely behind the central mesh; pv: in the laterally compressed portion of the carapace, near the posteroventral corner; pm: in the same portion, just above pv; pd: between the two ridges which form an inverted V below the posterior end of the dorsal ridge; d: dorsal, within the broad arch of the dorsal ridge; ac: small area above the downsloping anterior extension of the dorsal ridge. Inside the circumscribed peripheral areas there are two more: ad: anterodorsal, between the dorsal ridge and the upper median ridge, and dc: in the area between the central mesh (c) and the dorsal area (d).

Pokorn? (1968, 1969) further refined the system by numbering the meshes in more or less horizontal rows, numbers beginning at the posterior ends of the rows. In doing so, he combined avm and vc, adm, c, and cp and ad and dc, thereby ignoring the constant posi-

tion of the central mesh (c), which receives a different number in variants with more meshes to a row. Moreover, in the Caribbean material it is often ambiguous into exactly how many secondary meshes the larger areas are split; cross-ridges are often indistinct, in some cases barely indicated or even completely lacking. As a result, within the same popula- tion and, in undoubtedly conspecific specimens, the number of meshes may vary considerably. The numbers are very constant in some particular areas: vc and cp are normally subdivided into two meshes, rarely three. In other areas there is much greater variation especially in av, d, and ad. Therefore Pokorny's system is not followed here.

Text-figure 2 shows the variation of the reticulation in the Caribbean forms and compares it to that of the Galapagos species. It shows that R. confragosa compares most closely to the R. dictyon group, but has a more developed anterodorsal area (ac); R. sp. 2 is closest to the R. ponderosa group. Both Caribbean groups differ from the Gala- pagos groups in lacking a strongly developed, flange-like ventral ridge.

SYSTEMATIC PALEONTOLOGY

Subclass: OSTRACODA Order: PODOCOPIDA

Superfamily: CYTHERACEA

Family: TRACHYLEBERIDIDAE Subfamily: HEMICYTHERINAE

Genus: RADIMELLA Pokorny, 1969 RADIMELLA ex gr. CONFRAGOSA

(Edwards), 1944 P1. 1, figs. 1-17

Remarks.-All internal features (P1. 1, fig. 4) are typical of the genus Radimella. Nor- mal porecanals: both sieve type and simple pores occur, always clearly separated. The sieve pores are found on slightly elevated mounds in the interior of the meshes of the reticulation, frequently near their borders, close to the ridges which separate the meshes (P1. 1, figs. 13-16), especially in forms where the ridges are enlarged and thus encroach upon the meshes (P1. 1, figs. 5, 10, 11). The simple pores are always found on the ridges, rather irregularly distributed, lacking in some areas, crowded into groups of 3 to 4 in others, notably near the dorsal margin (P1. 1, fig. 13). The simple porecanals, which bear bristles, ob- viously have a tactile function. The less exposed sieve pores in the meshes must have another function, possibly they may serve as


Ah~h

ac d

d d cb

pd ~

dd

dp

;aa

adad dc

av(Z) OVM= P

v

IC

p

TEXT-FIG. 3-Radimella ex gr. confragosa (Edwards); simplified drawings after SEM photographs, all left valves. a, Radimella confragosa (Edwards), holotype, USNM 539423, Duplin marl, North Caro- lina, x 50. b, Radimella confragosa (Edwards), HVH 9094, from B 218 (de la Torre, 1966) Canimar Formation, Matanzas, Cuba, x70. c, Radimnella sp. 2, HVH 9107, from B 210 (de la Torre, 1966), Matanzas Formation, Matanzas, Cuba, X75. d, Radimella sp. 3, H\VH 9109, Recent, Half Moon Bay, Antigua, X75. e, Radimella ex gr. confragosa, (Edwards), generalized figure with explanation of hatched areas in figures a-d. f, Radimella dictyon Pokorni, after Pokorn', 1969. g, Radimella ponderosa Pokorny, after Pokornyi, 1969.


regulators of fluid exchange between the ani- mal and its environment.

On the basis of carapace morphology five forms can be distinguished within the group, but four of them are treated in open nomenclature as the taxonomic status of these forms is not clear. They may be considered by some as true species and therefore should receive formal names, or as extreme variants of R. confragosa by those who would admit a high degree of variability in this species.

RADIMELLA CONFRAGOSA (Edwards), 1944 P1. 1, figs. 1-4,16,17; Text-fig. 3a,b

Hemicythere confragosa EDWARDS, 1944, p. 518, P1. 66, figs. 23-26; SWAIN, 1951, p. 43, Pl. 6, figs. 13, 14; PURI, 1953, Pl. 1, figs. 4-6; 1954, p. 266, P1. 1, figs. 1-12; VAN DEN BOLD, 1958, p. 71 (part); BROWN, 1958, p. 66, P1. 7, fig. 1.

Aurila confragosa (Edwards) VAN DEN BOLD, 1963, p. 385 (part), not Pl. 8, fig. 1 = Radimella sp. 2; PURI & VANSTRUM, 1969, p. 74, 77, 78.

Mutilus confragosus (Edwards) VAN DEN BOLD, 1966a, table 1, 2, 5 (part, incl. Radimella sp. 1); 1966c, p. 1029 (part); 1966d, table 1; 1968, p. 19, 20, 30, 32, 35, 38 (part, incl. Radimella confragosa form A); SWAIN, 1968, p. 21, Pl. 4, figs. 8 a-e, P1. 5, figs. 5 a-c, P1. 7, figs. 3 a-c; VAN DEN BOLD, 1969, table 1 (part).

Mutilus confragosa (Edwards) PURI & VANSTRUM,

1969, p. 75 (part, incl. Radimella sp. 2). Radimella confragosa (Edwards) HAZEL, 1971a,

table 1; 1971 b, table 1; SWAIN, 1974, p. 36, P1. 6, figs. 11-13.

Radimella ex gr. confragosa (Edwards) VAN DEN BOLD, 1971, p. 337 (part); 1972a, p. 1010, table 2 (part) ; 1974, p. 537 (part); 1975, tables 2, 7, 9, 10, 12, 15 (part).

not Mutilus confragosa (Edwards) PURI, 1960, p. 130 (= probably Radimella sp. 3); SWAIN, 1967, p. 83, Text-fig. 52a, Pl. 6, fig. la, b = Mutihts aurita (Skogsberg) MCKENZIE & SWAIN, 1967, not Cythereis (Cythereis) aurita (Skogs- berg) ; SWAIN, 1969, p. 468.

not Aurila confragosa (Edwards) BAKER & HUL- INGS, 1966, p. 114, Pl. 1, fig. 13 = Radimella sp. 2.

not Mutilus confragosus (Edwards) VAN DEN" BOLD, 1966b, P1. 1, fig. 13 = Radimella sp. 2.

Deposited material.-HVH 9092-9095, 9992- 9995.

Diagnosis.-A species of Radimella with pronounced anterior cardinal angle, slightly bent dorsal margin; dorsal ridge flush with posterodorsal margin. Meshes of unequal size; ridge separating a-ac and ad-d very pronounced and sloping rather steeply forward to median ridges.

Distribution.-Southern Atlantic coastal plain: upper part of the Yorktown Formation (Plio- cene according to Akers, 1971; Hazel, 1971a), Duplin Formation (Pliocene? according to Hazel, 1971a; Oaks & DuBar, 1974), Wac-

camaw Formation (Pleistocene according to Oaks & DuBar, 1974); Florida: Ecphora and Cancellaria Zones of the Choctawhatchee Stage, Jackson Bluff Formation (Pliocene, according to Akers, 1971), Caloosahatchee For- mation (Pleistocene according to Oaks & Du- Bar, 1974) ; Cuba: Matanzas Formation (Pleistocene), Capas de Gypsina, Canimar and La Cruz Formations (Pliocene); the age assignments of these Cuban formations will be discussed in a forthcoming paper on the young Neogene of Cuba; Jamaica: Bowden Forma- tion sensu lato (Pliocene according to Blow, 1969; Lamb & Beard, 1972); Haiti: Morne Delmar Formation (Pliocene according to van den Bold, 1975); Dominican Republic: Gurabo Formation (earlier considered late Miocene by van den Bold, 1968, but correlated with the Globorotalia margaritae Zone, which is now considered Pliocene by Lamb & Beard, 1972), Mao Formation ( ?Pliocene according to Seiglie & Cucurullo, 1971), upper part of the Las Salinas Formation (Pliocene according to van den Bold, 1975); Puerto Rico: Ponce Forma- tion (considered as late Miocene by van den Bold, 1969, and Seiglie and Bermuidez, 1969; age questionable because of the scarcity of planktonic foraminifera; arguments for a Plio- cene age will be given in a forthcoming pub- lication on the young Neogene of Cuba); Trinidad: Springvale Formation (originally thought to be late Miocene, e.g., van den Bold, 1963, but later, van den Bold, 1966a, correlated with the upper part of the Cubagua Formation in Venezuela); Venezuela: upper part of the Cubagua Formation (Pliocene according to Lamb & Beard, 1972), Cabo Blanco Forma- tion (originally determined as Pliocene by Bermfidez & Bolli, 1969, but now considered Pleistocene on the basis of the occurrence of Globorotalia truncatulinoides, Blow, 1969), El Veral Formation (Pliocene according to van den Bold, 1972a); Colombia: Chorrera and

Tubarai Formations (Pliocene according to Bordine, 1974); Costa Rica: "Rio Banano" beds = Gatun Formation of Olsson, 1922 (Pliocene-Pleistocene, Blow's Zones N 18 to N 22, according to personal information from G. Taylor; Taylor, 1973); Mexico: Agueguex- quite Formation (Pliocene according to Akers, 1971).

RADIMELLA CONFRAGOSA form A

P1. 1, figs. 8-10

Mutilus confragosus (Edwards) VAN DEN BOLD, 1966c (part), p. 1029; 1968 (part), tables 4-13; 1969 (part), table 1.


Radimella ex gr. confragosa (Edwards) VAN DEN BOLD, 1971, p. 337 (part); 1975, tables 2, 3, 7, 9, 10, 12, 15 (part).

Deposited material.-HVH 9097-9101.

Diagnosis.-A species of the Radimella confragosa group with the dorsal ridge diverging posteriorly from the posterodorsal margin and

projecting over it. Dorsal margin strongly bent, anterior cardinal angle very pronounced.

Distribution.-Cuba: La Cruz Formation (Pliocene, see under Radimella confragosa); Jamaica: Bowden Formation (see under Radi- mella confragosa), Manchioneal Formation

(Pleistocene, according to Blow, 1969), Har- bour View beds (? Pleistocene, according to van den Bold, 1971); Haiti: Morne Delmar Formation (Pliocene, according to van den Bold, 1975); Dominican Republic: Jimani For- mation (?Pliocene-Pleistocene, according to van den Bold, 1975), Gurabo, Mao and Las Salinas Formations (Pliocene, according to van den Bold, 1975); Puerto Rico: Ponce For- mation (see under Radimella confragosa). Holocene in the Bahamas, North coast of

Jamaica, Bay of Port-au-Prince, Haiti, South coast of Puerto Rico and off Antigua.

RADIMELLA sp. 1 P1. 1, figs. 11,13,14

Aurila confragosa (Edwards) VAN DEN BOLD, 1963, p. 385 (part), Pl. 8, fig. 1.

Mutilus confragosa (Edwards) VAN DEN BOLD,

1966a, tables 1, 2, 5 (part). Radimella ex gr. confragosa (Edwards) VAN DEN

BOLD, 1972a, p. 1010, table 2 (part).

Deposited material.-HVH 9102, 9103.

Diagnosis.-A species of Radimella with subdued anterior cardinal angle, convex dorsal margin, dorsal ridge parallel and below dorsal margin. Meshes of about equal size

throughout; posterodorsal group of meshes wide.

Distribution.-Trinidad: Savaneta Member of Springvale Formation (Pliocene, about Zone N 18 of Blow, 1969) and Biche core holes (?N 17); Venezuela: Cubagua Formation of Cuba- gua #1: 258-270 ft (Pliocene, Globoquadrina altispira Zone of Berm'idez & Bolli, 1969), upper part of Cerro Verde and Cerro Macho Members of Cubagua Formation (Globorotalia margaritae Zone of Berm'idez & Bolli, 1969 -

top N 17 and N 18 Zones of Blow, 1969; see also Lamb & Beard, 1972); Costa Rica: Lower part of the "Rio Banano" beds = Gatun For- mation of Olsson (1922); top N 17 or N 18 Zones of Blow according to G. Taylor, personal commun. In Lamb & Beard's zonation

(1972) all these beds would correspond to Lower and Middle Pliocene.

RADIMELLA sp. 2 P1l. 1, figs. 5-7,15; Text-fig. 3c

Aurila confragosa (Edwards) BAKER & HULINGS, 1966, p. 144, Pl. 1, fig. 13.

Mutilus confragosus (Edwards) VAN DEN BOLD, 1966b, P1. 1, fig. 13.

Aurila confragosa (Edwards) PURI & VANSTRUM, 1969, p. 74, 77, 78 (part).

Mutilus confragosa (Edwards) PURI & VANSTRUM, 1969, p. 75.

Radirnella ex gr. confragosa (Edwards) VAN DEN BOLD, 1971, p. 337, tables 3, 4 (part); 1975, p. 590 (part).

Deposited material.-HVH 9104-9108. Diagnosis.-A species of Radimella with

slightly bent dorsal margin, dorsal ridge parallel to and below posterodorsal margin; anterior end less oblique than in R. confragosa and anterior cardinal angle less pronounced. Ven- tral meshes depressed.

Distribution.-Florida: Caloosahatchee For- mation (Pleistocene, according to Oaks & Du- Bar, 1974) ; Cuba: Jaimanites Formation (Pleistocene) and Matanzas Formation ( ?Pleis- tocene), information on these formations is contained in a forthcoming paper on the young Neogene of Cuba; Jamaica: Manchioneal For- mation (Pleistocene, according to Blow, 1969; Lamb & Beard, 1972); Costa Rica: Moin For- mation (Pleistocene, according to Akers, 1971, and personal communication from G. Taylor). Holocene: North coast of Cuba, Bay of San- tiago de Cuba, Bay of Port-au-Prince, Haiti, St. Lucia, Caribbean coast of Panama, British Honduras.

RADIMELLA sp. 3 P1. 1, fig. 12; Text-fig. 3d

?Mutilus confragosa (Edwards) PURI, 1960, p. 130.

Aurila confragosa (Edwards) VAN DEN BOLD, 1963, p. 365 (part).

Mutilus confragosa (Edwards) VAN DEN BOLD, 1966a, p. 14 (part).

Radimnella ex gr. confragosa (Edwards) VAN DEN BOLD, 1975, p. 590 (part).

Deposited material.-HVH 9109-9111. Diagnosis.-A species of Radimella with sin-

uate dorsal margin, dorsal ridge flush with posterodorsal margin; anterior end steeply oblique, anterior cardinal angle very pronounced. Posterodorsal group of meshes depressed.

Distribution.-Holocene: Florida Keys, Ba- hamas, Bay of Port-au-Prince, Haiti, Barbuda, St. Lucia, Antigua, Paria Shelf, North coast of Venezuela, Panama, Miskito Keys.


ACKNOWLEDGMENTS

This study forms part of the investigation of the post-Eocene Ostracoda of the Carib- bean, supported by National Science Founda- tion Grant GA-16522. Some of the electroscan pictures were made by R. H. Benson at the Smithsonian Institution and I am very grate- ful for his cooperation, and time and the use of these facilities. The others were made with Joelco scanning electron microscope of the School of Geoscience at Louisiana State Uni- versity, Baton Rouge. The aid of the graduate assistants J. Klasik, T. Naymik and R. Pierce is gratefully acknowledged.

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MANUSCRIPT RECEIVED APRIL 12, 1974 REVISED MANUSCRIPT RECEIVED FEBRUARY 18, 1975

EXPLANATION OF PLATE 1

All figures, except 4, are from the exterior of left valves.

FIGS. 1-4,16,17-Radimella confragosa (Edwards). 1, HVH 9093, from J 11c, Lower Coastal Group, Buff Bay section, Jamaica (van den Bold, 1971a), X60. 2, HVH 9092, from J 43a, Navy Island Member of the Manchioneal Formation, Navy Island, Jamaica (van den Bold, 1971a), x 60. 3, Holotype, USNM 559423, Duplin Marl, North Carolina, X100. 4, Paratype, interior of right valve, X 100. 16, HVH 9095, from B 222, Capas de Gypsina, Matanzas, Cuba (Ber- m idez, 1950), posterodorsal portion, x187. 17, Holotype, USNM 559423, central portion, x 145. Figures 3, 4 and 17 were photographed by R. H. Benson at the Smithsonian Institu- tion.

5-7,15--Radimella sp. 2. 5, HVH 9105, from P 29, Holocene, Hollandez Keys, San Blas, Panama, X60. 6, HVH 9108, from J 16, type locality of the Manchioneal Formation, Jamaica (van den Bold, 1971), X60. 7, HVH 9104, from M 22, type locality of the Caloosahatchee For- mation, Caloosahatchee River at Ayers Landing, Florida, X60. 15, same specimen, posterodorsal portion, X 525.

8-10-Radimella confragosa form A. 8, HVH 9100, from PR 3, Ponce Formation, Puerto Rico (van den Bold, 1969), X60. 9, HVH 9098, from loc. 15479, Gurabo Formation, Dominican Republic (van den Bold, 1968), x60. 10, HVH 9097, from loc. 15211, Gurabo Formation, Dominican Republic (van den Bold, 1968), x60.

11,13,14-Radimella sp. 1. 11, HVH 9102, from RR 124, Savaneta Member of the Springvale Formation, Trinidad (van den Bold, 1963), X60. 13, HVH 9103, from Cubagua #1, core 10 (258--270 ft), Cubagua Formation, Venezuela (van den Bold, 1966a), midportion of dorsal area, X1000. 14, same area as previous number, X 2900.

12-Radimella sp. 3. HVH 9109, Holocene, Half Moon Bay, Antigua, X66.


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DISTRIBUTION OF THE RADIMELLA CONFRAGOSA GROUP … Den Bold... · C + 1- Tubara C Miles 0 200 400 600 " 1 I I I ) \ 0 400 600 Kilometers " TEXT-FIG. 1-Fossil and Recent distribution