﻿68 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



Family ROTALIIDAE. 

 Genus DISCORBIS Lamarck, 1804. 



DISCORBIS OBTUSA (d'Orbigny). 



Plate 23, figs. la^c. 



Rosalina obtnsa d'Orbigny, Foram. Foss. Bafss. Tert. Vienne, 1846, p. 179, 



pi. 11, figs. 4-6. 

 Discorbina oMusa H. B. Beady, Rep. Voy. Challenger, Zoology, vol. 9, 1884, 



p. 644, pi. 91, figs. 9a-c. 

 Discorbis obtusa Cushman, Bull. 71. U. S. Nat. Mus., pt. 5, 1915, p. 13, 



figs. 12a-c. 



DesG7nptlon. — Test biconvex, dorsal side more so than the ventral 

 side, peripheral margin rounded ; chambers comparatively few, about 

 five in the last formed whorl; sutures curved, depressed; wall per- 

 forate; aperture an elongate narrow slit extending from the um- 

 bilicus nearly to the periphery. 



Diameter 6.60 mm. Cat. No. 324664, U.S.N.M. 



The only station from which this sj^ecies was obtained is U.S.G.S. 

 No. 5850, from Pleistocene marl near Mount Hope, a quarter mile 

 from the present sea beach and 6 to 8 feet above high tide. 



Genus TRUNCATULINA d'Orbigny, 1826. 



TRUNCATULINA AMERICANA, new species. 



Plate 23, figs. 2a~c. 



Description. — Test nearly plano-convex: ventral side strongly 

 convex, periphery keeled, dorsal side nearly flat; chambers numerous, 

 up to nine in the last formed coil ; sutures curved, prominent, slightly 

 limbate, imibilicate below; surface smooth, aperture nearly pe- 

 ripheral. 



Diameter 0.65 mm. 



Type-specimen. — (Cat, No. 324665, U.S.N.M.) from the upper 

 part of the Culebra formation, at U.S.G.S. No. 6019/, fourth limy 

 bed from bottom, Las Cascades section, Gaillard Cut. 



TRUNCATULINA PYGMEA Hantken. 



Plate 23, figs. 3a-c. 



Truncatulina pyymea Hantken, Mitth. Jahrb. ung. geol. Abstalt., vo! 4, 



1875, p. 78, pi. 10, fig. 8. 

 Truncatulina pygmaea H. B. Bbady, Rep. Voy. Challenger, Zoology, vol. 9, 



1884, p. 666, pi. 95, figs. 9, 10. 



