Maryland Geological Survey 525 



CtENOBOLBINA ? DUBIA n. sp. 

 Plate XCVI, Figs. 10-12 



Description. — Carapace subovate except that the dorsal edge is nearly 

 straight. As oriented, the posterior end is the narrower, but considerably 

 the thicker. An undefined broad median sulcus confined to the dorsal 

 half; otherwise the valve is without furrows. Posterior half of dorsal 

 edge somewhat excavated, forming a straight shoulder descending 

 abruptly ; ventral edge thick, with a rather narrow flange around the ends 

 and ventral portion. Surface smooth. 



Length 1.00 mm. ; height .62 mm. 



The position of this species is altogether doubtful. There is a general 

 resemblance to Ctenobolbina, but the sulcus is so shallow and limited in its 

 extent, and the shape of the valve so different from the average of that 

 genus, that the species really belongs here. In general expression again, 

 as also in the thick ventral edge, considerable agreement is noted with 

 certain similarly thick-edged Primitias. Finally, it is not altogether im- 

 probable that the species is nearer the type of Halliella than any other. 

 However, until all of these various Primitian genera shall have been re- 

 vised, the position assigned the species will serve the purpose of classifica- 

 tion provisionally. 



Occurrence. — Helderberg FoRiiAxiox, Keyser Member. Cumber- 

 land. 



Collections. — Mai7land Geological Sun-ey, U. S. National Museum. 



Genus BOLLIA Jones and HoU 

 BOLLIA AMERICANA n. sp.* 



Plate XCVI, Figs. 13-15 



Description. — This well-marked BoUia is closely related to the type of 

 the genus, B. uniflexa Jones and Holl, and also to the somewhat similar 



' Compare Bollia Ucollina Jones and Holl, 1886, Ann. and Mag. Nat. Hist. (5), 

 VOL xvii, p. 3G1, pi. xil, flgs. 14-16, and B. uniflexa, ibid., figs. 17a, 17b. 



