STUDIES m FORAMINIFERA 



77 



zone. G. aequa and G.jormosa both coil predominantly 

 dextrally in the Globorotalia rex and Globorotalia 

 formosa formosa zones of the upper Lizard Springs. 



Globorotalia compressa (Plummer) 

 Plate 20, Figures 21-23 



Globigerina compressa Plummer, Univ. Texas Bull. 2644, p. 135, 



pi. 8, fig. 8, 1926. 

 Globorotalia compressa (Plummer), Bronnimann, Bull. Amer. 



Paleontol., vol. 34, No. 143, p. 25, pi. 2, figs. 19-24, 1952. 



Shape of test very low trochospiral, inflated; equa- 

 torial periphery distinctly lobate, slightly elongate ; axial 

 periphery subacute to acute. Wall calcareous, per- 

 forate, siuface smooth. Chambers slightly com- 

 pressed; 12-15, arranged in about 2}i whorls, the 4-5 

 chambers of the last whorl increasing fau'ly rapidly in 

 size. Sutures on spiral side radial to slightly curved in 

 early chambers, radial in last chambers, depressed; on 

 umbilical side radial, depressed. Umbilicus fairly 

 wide, open. Aperture a distinct arch, may have a 

 slight lip; interiomarginal, extraumbilical-umbilical. 

 Coiling random. Largest diameter of figured hypo- 

 type 0.23 mm. 



Stratigraphic range: Globorotalia trinidadensis 

 zone to Globorotalia pusilla pusilla zone, Lizard Springs 

 formation. 



Locality: Figured hypotype (USNM P5059) from 

 Trinidad Leaseholds, Ltd., well Guayaguayare 159, 

 Trinidad (coordinates N:151361 links; E:554095 links), 

 sample from core 4,524-36 feet (TLL 232705). 



Remarks: Globorotalia compressa (Plummer) is the 

 ancestor of G. ehrenbergi BoUi, new species, from which 

 it is distinguished by its smaller size, less compressed 

 chambers and absence of a peripheral keel. 



Globorotalia ehrenbergi BoUi, new species 



Plate 20, Figures 18-20 



Globorotalia membranacea (Ehrenberg), White, Journ. Pale- 

 ontol., vol. 2, p. 280, pi. 38, fig. 1, 1928. — Cushman and 

 Bermudez, Contr. Cushman Lab. Foram. Res., vol. 25, 

 No. 2, pp. 34, 35, pi. 6, figs. 16-18, 1949. 



Shape of test low trochospiral, compressed; equa- 

 torial periphery strongly lobate ; axial periphery acute, 

 last chamber often with a faint keel. Wall calcareous, 

 perforate, surface smooth. Chambers compressed; 

 about 12-15, arranged in 2-3 whorls, the 5 chambers 

 of the last whorl increasing fairly rapidly in size. 

 Sutures on spiral side shghtly curved, distinctly de- 

 pressed; on umbilical side radial, depressed. Umbilicus 

 shallow, open. Aperture a low arch, with a lip; in- 

 teriomarginal, extraxmibilical-umbilical. Coiling ran- 

 dom. Largest diameter of holotype 0.28 mm. 



Stratigraphic range: Globorotalia pusilla pusilla 

 zone to Globorotalia pseudomenardii zone, Lizard Springs 

 formation. 



Locality: Holot3T)e (USNM P5060) from Trinidad 

 Leaseholds, Ltd., well Guayaguayare 159, Trinidad 

 (coordinates N:151361 links; E:554095 links), sample 

 from core 4,524-36 feet (TLL 232705). 



Remarks: Globorotalia membranacea (Ehrenberg) has 



frequently occurred in the literature (see Cushman 

 and Bermudez, 1949, p. 34). Ehrenberg (1854) figured 

 imder Planulina membranacea the spiral views of 2 

 rotalid Foraminifera from the Cretaceous that are at 

 least specifically different. Of these, one (pi. 26, fig. 

 43) could be near to a form subsequently described on 

 several occasions as Globorotalia membranacea (for 

 example, from Trinidad by Cushman and Renz, 1946). 

 No description or depository of a holotype was given 

 by Ehrenberg however. It is for these reasons that a 

 new name had to be chosen for these Paleocene speci- 

 mens described as Globorotalia membranacea. Glo- 

 borotalia ehrenbergi developed from Globorotalia com- 

 pressa (Plummer) and is regarded as the ancestor of 

 Globorotalia pseudomenardii Bolli, new species, and 

 possibly of Globorotalia elongata Glaessner. 



Globorotalia pseudomenardii BoUi, new species 



Plate 20, Figures 14r-17 



IGloborotalia pseudoscitula Glaess.ner, Studies in Micropal- 

 eontol., Publ. Lab. Paleontol., Moscow Univ., vol. 1, pt. 

 1, pp. 32-33, figs. 3a-c, 1937. 



Shape of test veiy low trochospiral, biconvex; equa- 

 torial periphery elongate, lobate, especially so in large 

 specimens; a.xial periphery angular with distinct keel. 

 WaU calcareous, perforate, surface smooth. Chambers 

 strongly compressed; about 15, arranged in 3 whorls, 

 the 5 chambers of the last whorl increasing rapidly in 

 size. Sutures on spiral side strongly curved, especially 

 so between last chambers of large specimens, depressed; 

 on umbilical side radial, depressed. Umbilicus shallow, 

 open. Aperture a low arch with a lip; interiomarginal, 

 extraumbiUcal-umbilical. Largest diameter of holo- 

 type 0.34 mm., of figured paratype 0.66 mm. 



Stratigraphic range: Globorotalia pseudomenardii 

 zone. Lizard Springs formation. 



Locality: Holotype (USNM P5061), paratype 

 (USNM P5062) from Trinidad Leaseholds, Ltd., 

 well Guayaguayare 159, Trinidad (coordinates N:l 5 1361 

 links; E:554095 links), sample (holotype) from core 

 4,324-30 feet (TLL 233004); sample (paratype) from 

 core 3,992^,000 feet (TLL 233000). 



Remarks: Globorotalia pseudomenardii Bolli, new 

 species, is closely related to G. ehrenbergi Bolli, new 

 species, from which it apparently developed and from 

 which it is distinguished by its less lobate periphery 

 and less depressed spiral sutures. The name has been 

 chosen for the resemblance to small specimens of G. 

 menardii (d'Orbigny), to which it has no genetic re- 

 lationship however. G. pseudomenardii becomes ex- 

 tinct at the close of the Paleocene whereas G. menardii 

 appears first in the middle to upper Miocene. 



Globorotalia elongata Glaessner 



Plate 20, Figures 11-13 



Globorotalia pseudoscitula var. elongata Glaessner, Studies in 

 Micropaleontol., Publ. Lab. Paleontol., Moscow Univ., 

 vol. 1, pt. 1, p. 33, figs. 3d-f, 1937. 



Shape of test very low trochospiral, compressed, spiral 



