40 The Fauna of the Keyskk ^[e:\iber of the 



WniTFIELDELLA ( ?) MINUTA n. sp. 



Plate LXXIII, Figs. 41, 42 



Description. — Shell small to minute, elongated in a direction from beak 

 to base, giving to the shell a somewhat snbovate outline. Both valves 

 strongly convex, gibbous to somewhat ventricose, lateral and antero-lateral 

 margins regularly rounded, cardinal margins convex, but these curves are 

 sharper than the curves of the anterior margin. Ventral valve the longer, 

 convex, gibbous to subventricose. Greatest convexity just posterior to the 

 middle of the valve. Beak slightly incur\ed, prominent, pointed, extend- 

 ing beyond that of the dorsal valve. Dorsal valve regularly convex, 

 gibbous, greatest convexity in the umbonal region; beak pointed, incurved, 

 filling the delthyrium of the ventral valve. Surface smooth or marked by 

 very faint obscure concentric lines of growth and on exfoliated individuals 

 fine silk-like striations radiate from the beak. No fold or sinus on either 

 valve. In some individuals the anterior portion is prolonged into a modi- 

 fied linguiform extension, while in other individuals the anterior margin 

 is rounded. 



Size of largest individual 3 mm. long and 2 mm. wide. 



This species is distinguished by its minute size. There is no fuld or 

 sinus on either valve. 



Occurrence. — Heldekbekg Formation, Keyser Member. Devil's 

 Backbone, Bound top. 



Collection. — ]\Iaryland Geological Survey. 



MOLLUSCA 



Class PELECYPODA 



Order PRONODESM ACE A 

 Section PALAEOCONCHA 



Family GRAMMYSllDAE 



Genus GRAMMYSIA Vemeuil 



Grammysia sp. ? 



Plate LXXV, Fig. 1 



Description. — An iiicomplete individual, evidently belonging to this 



genus has been found in the Keyser member. It is the only representative 



