92 



XnJITED STATES NATIONAL MUSEUM BULLETIN 216 



but the biserial chamber arrangement is maintained 

 throughout the test. 



Chiloguembelina victoriana, new species, difiFers from 

 Chiloguembelina cuhensis (Palmer) in its higher and 

 narrower aperture, smooth wall surface, and somewhat 

 less inflated chambers. 



The name Chiloguembelina victoriana is derived from 

 the county of Victoria, Trinidad, where the species is 

 found in various sm-face locahties (San Fernando area, 

 Cipero Coast section) . 



Length: 0.15-0.22 mm.; holotype, 0.2 mm. 



Occurrence: San Fernando formation (upper 

 Eocene), Globorotalia cocoaensis zone. Cipero forma- 

 tion (OHgocene), Globigerina ampliapertura zone (lower 

 part). 



Types: Figured holotype (USNM P5789) and para- 

 types (USNM P5790, P5791a-c), unfigured paratypes 

 (USNM P5792). 



Chiloguembelina wilcoxensis (Cushman and Ponton) 



Plate 21, Figitbes 10, 12, 13; Text-figtjre 15 (49-58) 



Gumhelina wilcoxensis Cushman and Ponton, 1932, p. 66, pi. 

 8, figs. 16, 17 (lower Eocene, Alabama, U. S. A.). — Toulmin, 

 1941, p. 597, pi. 80, fig. 24 (lower Eocene, Alabama, U. S. A.) . 



With its globular chambers and its symmetrical, 

 semicircular aperture, Chiloguembelina wilcoxensis is 

 easily distinguished from other Chiloguembelina species, 

 but is similar to some Cretaceous species of Heterohelix 

 (formerly Guembelina). 



Loeblich and Tappan (1956) do not mention this 

 species among those to be included in Chiloguembelina. 

 However, like C. trinitatensis Cushman and Renz, 

 which has no twisted test or asymmetrical apertural 

 flap either, it seems to develop from C. crinita, which 

 is a typical Chiloguembelina (see p. 89). Therefore C. 

 trinitatensis and C. wilcoxensis are probably not directly 

 related to the Cretaceous Heterohelix. The genus 

 description of Chiloguembelina does not exclude species 

 with symmetrical test. The necklike extension of the 

 aperture mentioned by Loeblich and Tappan is present 

 in many specimens of C. wilcoxensis, especially the 

 earlier ones. 



There is a distinct increase in size from the lowest to 

 the highest occurrence of the species. A few specimens 

 show a small end chamber covering the aperture of the 

 last regular chamber, as in plate 21, figure 13, and text- 

 figure 15 (No. 56). 



Length: 0.2-0.58 mm. 



Occurrence: Lizard Springs formation (Paleocene 

 and lower Eocene), Globorotalia pseudomenxirdii zone 

 to Oloborotalia formosa formosa zone. 



Types: Figured hypotypes (USNM P5793, P5794, 

 P5795, P5796a-d, P5797a-^, P5798a-c) and unfigured 

 hypotypes (USNM P5799). 



ChiloguemLelina sp. 



Plate 21, Figure 18 



Rather slender, elongate, more or less compressed 

 specimens with a low, arched, asymmetrical apertiu-e 



are fairly conamon in the lower and middle part of the 

 Navet formation. They are rather badly preserved 

 and several important characters, e. g., wall surface 

 and exact shape of the aperture, are difficult to deter- 

 mine. Specimens similar to the figured type are 

 particularly frequent, others resemble Chiloguembelina 

 garretti (Howe) and Chiloguembelina victoriana n. sp. 



Length: 0.15-0.24 mm. 



Occurrence: Navet formation (Eocene), Hantkenina 

 aragonensis zone to Globorotalia lehneri zone. Scarce 

 and not typical specimens occur in the Porticulasphaera 

 mexicana zone. 



Types: Figured specimen (USNM P5800). 



Genus Guembelitria Cushman, 1933 

 Cuembelitria columbiana Howe 



Plate 21, Figure 16 



Oumbelitria columbiana Howe, 1939, p. 62, pi. 8, figs. 12-13 

 (Eocene, Louisiana, U. S. A.). — Cushman and Todd, 

 1945a, p. 16, pi. 4, fig. 3 (Eocene, Alabama, U. S. A.).— 

 Husset, 1949, p. 131 (Eocene, Louisiana, U. S. A.). 



Typical representatives of this species are common 

 in the lower and middle part of the Navet formation. 



Length: 0.12-0.18 mm. 



Occurrence: Navet formation (Eocene) , Hantkenina 

 aragonensis zone to Poiiiculasphaera mexicana zone. 



Types: Figured hypotype (USNM P5801) and un- 

 figured hypotypes (USNM P5802). 



Genus Zeauvigerina Finlay, 1939 



Zeauvigerina aegyptiaca Said and Kenawy 



Plate 21, Figures 9, 11; Text-figure 15 (59-62) 



Zeauvigerina aegyptiaca Said and Kenawt, 1956, p. 141, pi. 

 4, fig. 1 (Maestrichtian and Paleocene, Egypt) . 



The specimens from Trinidad agree in shape and 

 size with the type description. The stratigraphic 

 range of the species seems to be shorter than in Egypt. 

 In Trinidad, it is restricted to the upper part of the 

 Paleocene. This is about the same level as that of 

 the type sample (No. 8, Nekhl section, see Said and 

 Kenawy, 1956, p. 107, text-fig. 1). 



There is considerable variation in length and breadth 

 of the test. The size and shape of the last chamber is 

 very irregular, and the terminal neck with the aper- 

 ture can be short and wide or long and narrow. The 

 wall of the last chamber is thiiiner and more fragile 

 than that of the previous chambers. 



There is some controversy about the relationship 

 between Zeauvigerina Finlay, 1939, and Eouvigerina 

 Cushman, 1926 (LoebHch, 1951, p. 110; Said and 

 Kenawy, 1956, p. 141). The arrangement of chambers 

 is biserial in both genera. The main difference Hes 

 in the last chambers. In Zeauvigerina the long aper- 

 tural neck is present in the terminal end chamber 

 only. If this chamber is missing or broken off, the 

 test looks like a Chiloguembelina. The aperture is 

 then at the base of the last chamber, semicircular and 

 often slightly eccentric in position (see pi. 21, fig. 9). 



