Maryland Geological Survey Gil 



teriov margin obliq^ie, curving but slightly below the sulcus limiting 

 anterior extremity; ventral margin rounded; posterior margin nearly 

 straight, making a slight angle with anterior margin to which it is nearly 

 parallel. Left valve convex, point of greatest convexity slightly anterior 

 to middle. Umbo obtuse, projecting a little beyond hinge-line. Anterior 

 extremity large, subangular, its surface concave near point, convex to- 

 wards body from which it is separated by a depression which increases 

 in depth towards anterior margin. Wing not much longer than anterior 

 extremity, its posterior margins slightly concave. Separated from body 

 by a depression which becomes deeper near hinge-line. 



Length of hinge 22 mm.: length of body 48 mm. 



Eight valve only ubserved. This species differs from previously de- 

 scribed species in its vei'y long narrow body. 



Occurrence. — Jennings Formation, Chemung Member. Keyser- 

 Piedmont Eoad, 21/2 miles west of Keyser near top of Chemung; Cum- 

 berland-Barrelville Eoad near top of Chemung, 570 feet west of upper 

 conglomerate. 



Collection.' — ^Maryland Geological Survey. 



Family AMBONYCHIIDAE 



Genus GOSSELLETIA Barrois 



Gosselletia sp. 

 Plate LXIIT, Fig. 21 



Description. — Shell triangular, body oblique, length less than height. 

 Anterior margin straight, forming nearly a right angle with cardinal 

 margin at umbo; ventral margin curving to meet posterior margin. Left 

 valve only observed. Its umbo elevated, side flattened, anterior and dorsal 

 margins abruptly incurved. Hinge-line straight, nearly equalling length 

 of shell. Ligamental area wide, striated. Surface not observed. 



Length 58 mm.; height 48 mm. 



The cast of the interior of a single valve only has been observed, which 

 is not sufficiently well preserved to permit confident specific determination. 

 41 



