24 PEOCEEDINGS OF THE NATIONAL MUSEUM vol.80 



and are strongly curved, continuing nearly to the periphery on the 

 inner margin. There is a supplementary slit in the median line of 

 the apertural face, placing this species in the genus Rohulus^ as was 

 indicated by Eeuss, who placed it in Robulina. 



Genus LENTICULINA Lamarck, 1804 



LENTICULINA NAVICULA (d'Orbiffny) 



Plate 7, Figures 5 a, & 



Cristellai'ia namcula d'Orbigny, Mem. Soc. Gr§ol. France, s6r. 1, vol. 4, p. 27, 

 pi. 2, figs. 19, 20, 1840.— Reuss, Verstein. Bohm. Kreide, pt. 1, p. 35, pi. 12, 

 fig. 27, 1845^6. 



D'Orbigny described this species from the Cretaceous chalks of the 

 Paris Basin, and Eeuss and others have recorded it from the Creta- 

 ceous of central Europe. Our specimens from Trinidad seem to 

 agree very well with those of Europe and may be identified with 

 d'Orbigny's species. The chambers are distinct but not inflated, 

 the periphery subacute, the sutures flush with the surface but strongly 

 curved, and the apertural face convex without any supplementary 

 slit, so that this species may be included in Lamarck's genus. There 

 is a tendency in the later chambers toward uncoiling. The measure- 

 ments of the figured specimen are as follows : Length, 0.9 ; breadth, 

 0.55 ; thickness, 0.4 mm. 



This species is also widely distributed in the Coastal Plain region 

 of the United States in the Upper Cretaceous. 



LENTICULINA NUDA (Reuss) 

 Plate 7, Figures 6 a, b 



Cristellaria nudu Reuss, Sitz. Akad. Wiss. Wien, vol. 44, pt. 1, p. 328, pi. 6, 



figs. 1-3, 1861 (1862). 

 Lenticulma nuda Cushman and Jakvis, Contr. Cushman Lab. Foram. Res., vol. 



4, p. 96, pi. 14, fig. 2, 1928. 



This species, described by Reuss from the Cretaceous of Europe 

 and recorded by various authors from the same region, is already 

 noted by us from Trinidad. There is no supplementary aperture so 

 far as our material shows. The species is somewhat similar to the 

 preceding, but the apertural face is more concave and the periphery 

 more distinctly keeled. There is a distinct tendency to uncoiling, 

 and the chambers are lower. Our figured specimen has the following 

 measurements: Length, 0.8; breadth, 0.4; thickness, 0.28 mm. 



Genus PLANULARIA Defrance, 1824 



PLANULARIA ADVENA, new species 



Plate 8, Figubes 1, 2 



Description. — Test large, much compressed, periphery acute and 

 slightly keeled ; chambers distinct, low and broad, uniformly increas- 



