114 



XJNITED STATES NATIONAL MUSEXJM BULLETIN 215 



Nos. 6 a, b). Typical Globigerinoides rubra specimens 

 of Cipero age appear indistinguishable from Recent 

 forms. However, in Trinidad the species disappears at 

 the close of the Cipero time, shortly after the extinction 

 of Olohototalia fahsi robusta, and is not found in the 

 Lengua formation. Globigerinoides rubra apparently 

 made its return to Trinidad agaiu in late Miocene time. 

 Together with Globigerina bulloides d'Orbigny it is 

 found in the Upper Miocene Melajo formation. An 

 explanation for the absence of Globigerinoides rubra m. 

 the Lengua formation might be found in assuming that 

 the environmental conditions of the Lengua sea were 

 not favorable for the life habits of the species. 



Globigerinoides diminuta Bolli, new species 

 Plate 25, Figures 11 a-c 



Shape of test trochospiral; equatorial periphery al- 

 most subquadrate; axial periphery rounded. Wall 

 calcareous, perforate, surface finely pitted. Chambers 

 spherical in early stages, later becoming laterally some- 

 what compressed ; about 10, arranged in about 2K whorls ; 

 the 3 chambers of the last whorl increase moderately 

 in ■size. Sutures on spiral side radial, slightly depressed; 

 on umbilical side radial, slightly depressed. Umbilicus 

 smaU. Primary aperture small, almost circular, sym- 

 metrically above the suture line of the two previous 

 chambers; interiomarginal, umbilical; supplementary 

 sutural apertures, usually 2 of which are visible, are of 

 similar shape and occupy the same symmetrical posi- 

 tion over the sutures of earlier chambers. Coiling 

 ?random. Largest diameter of holotype 0.27 mm. 



Stratigraphic range (in Cipero formation): Globi- 

 gerinatella insueta zone. 



Locality: Holotype (USNM P5638) from the 

 Globigerinatella insueta zone, Trinidad, core 7,419-39 

 feet of United British Oilfields of Trinidad, Ltd. (now 

 Shell Trinidad, Ltd.), well Penal No. 92. 



Remarks: Globigerinoides diminuta, new species, is 

 separated from Globigerinoides rubra (d'Orbigny) by its 

 constantly very small size and more compact shape. 

 The position of the apertures symmetrically above the 

 suture between two earlier chambers is a characteristic 

 feature in both species. In contrast to Globigerinoides 

 rubra, the new species is confined to the Globigerinatella 

 insueta zone (probably to the lower part) . 



Globigerinoides mitra Todd 



Plate 26, Figures la-4 



Globigerinoides mitra Todd, U. S. Geol. Surv., Prof. Paper 280-H, 

 p. 302, pi. 78, figs. 3, 6, 1956. 



Stratigraphic range (in Cipero and Lengua for- 

 mations): Catapsydrax dissimilis zone to Globorotalia 

 menardii zone. 



Locality: Figured hypotypes (USNM P5639a-c) 

 from the Globorotalia menardii zone and (USNM 

 5640) from the Globorotalia fohsi fohsi zone, sample 

 KWB 6572 (TTOC 100219). 



Remarks: Scarce specimens of the large Globiger- 

 inoides mitra may occur from the Catapsydrax dissimilis 



zone onward. In the transitional beds between the 

 Lengua formation and the Cruse formation, where 

 they are more often encountered than deeper in the 

 section, the tests of Globigerinoides mitra are usually 

 pyritized. It appears possible that these abnormally 

 large forms have developed from Globigerinoides ob- 

 liqua, new species, by the development of additional 

 chambers. The large specimen of Globigerinoides ob- 

 liqua (pi. 25, figs. 9a-c) and Globigerinoides species 

 (pi. 26 figs. 5a-c) (USNM P5641) are possibly transi- 

 tional forms. 



Globigerinoides bispherica Todd 



Plate 27, Figures la-b 



Globigerinoides bispherica Todd, in Todd, Cloud, Low, and 

 Schmidt. Amer. Journ. Sci., vol. 252, No. 11, p. 681, pi. 

 1, figs, la-c, 4, 1954. — Blow, Micropaleontol., vol. 2, 

 No. 1, p. 62, text-fig. 1, Nos. 4-8, text-fig. 2, Nos. 10-11, 

 1956. 



Globigerina conglobata (H. B. Brady), Cushman and Stain- 

 PORTH, Cushman Lab. Foram. Res., Spec. Publ. 14, p. 68, 

 pi. 13, fig. 6, 1945. 



Stratigraphic range (in Cipero formation) : Upper 

 part of the Globigerinatella insueta zone. 



Locality: Figured hypo type (USNM P5642) from 

 the Globigerinatella insueta zone; sample KWB 7446A 

 (TTOC 125125). 



Remarks: Globigerinoides bispherica is regarded as 

 the ancestor of the Porticulasphaera glomerosa (Blow) 

 group and the genus Orbulina, (See Blow, 1956). 



Genus Sphaeroidinella Cuskman, 1927 



Sphaeroidinella grimsdalei (Keijzer) 



Plate 26, Figures 8-1 2c 



Globigerina grimsdalei Keijzek, Univ. Utrecht, Geogr. Geol. Med., 



Phys. Geol. Reeks, ser. 2, No. 6, p. 205, tf. 33a-d, 1945. 

 Globigerina cf. digitata (Brady), Cushman and Stainpoeth, 



Cushman Lab. Foram. Res., Spec. Publ. 14, p. 68, pi. 13, 



figs. 5a-b, 1945. 

 Globigerina digitata (Brady), Beemudez, Cushman Lab. Foram. 



Res., Spec. Publ. 25, p. 280, pi. 21, figs. 54r-55, 1949. 

 Globigerinoides grimsdalei (Keijzer), Bermudez, Cushman Lab. 



Foram. Res., Spec. Publ. 25, p. 281, pi. 21, figs. 56-57, 



1949. 

 Stratigraphic range (in Cipero and Lengua for- 

 mations) : Globorotalia fohsi barisanensis zone to Globo- 

 rotalia menardii zone. 



Locality: Figured hypotypes (USNM P5643a-c) 

 from the type locality of the Globorotalia fohsi fohsi 

 zone, sample Bo 185A (TTOC 193121), and (USNM 

 P5644a, b) from the type locality of the Globorotalia 

 mayeri zone, sample KR 23422 (TTOC 160634). 



Remarks: Sphaeroidinella grimsdalei is rather vari- 

 able in size and in number of chambers comprising the 

 finial whorl. Stratigraphically early specimens are 

 usually small with 3 chambers in the last whorl. During 

 the course of evolution, the tests tend to become larger 

 and the last whorl may consist of 3 and 4, occasionally 

 even 5 or 6, chambers. Sphaeroidinella rutschi Cush- 

 man and Renz probably branched off from Sphaeroidi- 

 nella grimsdalei. An apparently transitional form is 

 shown on plate 26, figures 13a, b (USNM P5646). 



