STUDIES IN FORAMINrFERA 



faint double keel, which is reduced to a single keel in 

 the last and penultimate chamber. Wall: calcareous, 

 perforate, surface smooth. Chambers: moderately 

 compressed; 12-15, arranged in 3 whorls; the 4 cham- 

 bers of the last whorl increase rapidly in size, early 

 whorls small by comparison. Sutures: spiral side 

 slightly curved, depressed; umbilical side nearly radial, 

 depressed. Umbilicus: wide. Apertures: primary ap- 

 ertures interiomarginal, imibihcal; tegilla with accessory 

 apertures not preserved in examined specimens. Coil- 

 ing: the 50 specimens counted coiled dextrally. 



Dimensions of holotype: diameter 0.49 mm.; thick- 

 ness 0.24 mm. 



Range: Globotruncana concavata zone, Naparima Hill 

 formation. 



Type and occurrence: Holotype (USNM P4805) 

 from Trinidad Leaseholds weU Marac 1, Trinidad 

 (coordinates N:152141 links, E:424447 links), sample 

 from core 8,332-8,362 feet (TLL 176080). 



Remarks: Globotruncana wilsoni, new species, differs 

 from Globotruncana lapparenti bulloides Vogler in having 

 only 4 chambers in the last whorl. The general outhne 

 of the equatorial periphery is more oval compared with 

 the more circular form of bulloides, and the 2 keels are 

 more closely spaced and often reduce to one in the last 

 chamber. Globotruncana wilsoni, new species, occurs 

 in the Globotruncana concavata zone, before the advent 

 of typical Globotruncana lapparenti bulloides. Transi- 

 tional forms between Globotruncana wilsoni, new species, 

 and Globotruncana fomicata Plummer have been ob- 

 served. 



The species is named in honor of Mr. C. C. Wilson, 

 Chief Geologist of Trinidad Petroleum Development, 

 Ltd. 



Globotruncana gagnebini Tilev 



Plate 14, igures 5a-o 



Globotruncana gagnebini Tilev, Bull. Lab. Gdol., Min., Gdophys., 

 Mus. G6ol., Univ. Lausanne, No. 103, p. 50, pi. 3, figs. 

 2-5, and text figs. 14a-17d, 1952. 



Shape of test: very low trochospiral, dorsal side flat, 

 mnbilical side strongly convex; equatorial periphery 

 distinctly lobate with 2 closely spaced keels, occasionally 

 reduced to one in last chamber. Wall: calcareous, 

 perforate, surface smooth. Chambers: angular, in- 

 flated; about 14, arranged in 2K whorls; the 4-5 cham- 

 bers of the last whorl increase rapidly in size, early 

 whorls small by comparison. Sutures: spiral side 

 curved, raised, beaded in early whorls; umbilical side 

 radial, depressed. Umbilicus: deep, wide. Apertures: 

 primary apertures interiomarginal, imibiUcal; tegilla 

 with accessory apertinres missing or only poorly pre- 

 served in examined specimens. Coiling: predominantly 

 dextral; of 50 specimens counted, only 2 coiled sinis- 

 traUy. 



Dimensions of figured hypotype: diameter 0.48 mm. ; 

 thickness 0.23 mm. 



Range: Globotruncana gansseri zone to Abathomphalus 

 mayaroensis zone, Guayaguayare formation. 



Type and occurrence: Figured hypotype (USNM 



896818—87 S 



P4806) from outcrop on right bank of Gautier River 

 (right side branch of Cunapo River) about 1,100 feet 

 southwest, above junction of waterfall branch (Chert 

 Hill), lYi miles southeast of Mamon-Guaico-Tamana 

 Road, eastern Central Range. Sample G. 3644A 

 (TLL 226184). 



Remarks: In its general shape, Globotruncana gagne- 

 bini Tilev shows similarities to Globotruncana ventricosa 

 White but differs in the following: 4-5 chambers in 

 last whorl, rapidly increasing in size, against 6-7 in 

 Globotruncana ventricosa, where the increase in size is 

 slower. The peripheral double keel is less pronounced 

 in gagnebini and the stratigraphic range is different 

 (Maestrichtian for Globotruncana gagnebini, Campanian 

 for Globotruncana ventricosa). Furthermore, Globo- 

 truncana gagnebini is somewhat smaller in size and less 

 robust. The Globotruncana ventricosa of Maestrichtian 

 age mentioned by the author in his earlier paper (1951) 

 on Trinidad Globotruncana are now regarded as Globo- 

 truncana gagnebini. Typical Globotruncana ventricosa 

 have been recorded in Trinidad from the upper part of 

 the Naparima Hill formation. 



Globotruncana andori de Klasz 



Plate 14, Figures 6a-c 



Globotruncana andori De Klasz, Geol. Bavarica, No. 17, p. 233, 

 pi. 6, figs, la-c, 1953. 



Shape of test: very low trochospiral, spiral side 

 almost flat, umbilical side strongly convex; equatorial 

 periphery nearly circular, with distinct single keel. 

 Wall: calcareous, perforate, siu-face smooth. Cham- 

 bers: subangular, inflated; about 15, arranged in 2-3 

 whorls, 6 chambers in last whorl. Sutures: spiral side 

 curved, raised, slight^ beaded; umbilical side slightly 

 curved, shghtly depressed. Umbilicus: deep, wide. 

 Apertiires: primary apertures interiomarginal, umbili- 

 cal; tegilla with accessory apertures not preserved in 

 examined specimens. Coiling: the limited number of 

 specimens counted coiled dextrally. 



Dimensions of figured hypotype: diameter 0.67 mm., 

 thickness 0.47 mm. 



Range: Globotruncana lapparenti tricarinata zone, 

 Guayaguayare formation. 



Type and occurrence: Figured hypotype (USNM 

 P4807) from Trinidad Leaseholds well Guayaguayare 

 163, Trinidad (coordinates N: 157646 links, E: 572808 

 links), sample from 5,961 K feet (TLL 153681). 



Remarks: Note that the species Globotruncana 

 cretacea Cushman and G. cf. calcarata Cushman, which 

 were mentioned as occurring in Trinidad (BoUi, 1951), 

 are left out of the present distribution chart. Forms 

 originally referred to as Globotruncana cretacea are now 

 regarded as being closer to Globotruncana gagnebini 

 Tilev. The specimens of Globotruncana cf. calcarata 

 (BoUi, 1951, pi. 35, figs. 16-18) differ in size and shape 

 from the typical form. They have only been found so 

 far reworked in the Upper Eocene. Though it is likely 

 that they come from the Guayaguayare formation, the 

 exact stratigraphic position remains imcertain. 



