102 



PALEONTOLOGY OF NEW-VOI!K. 



younger specimens are neat and well defined, preserving the carina and concentric folds which 

 become obsolete in older specimens. The shell originally has been very convex, but, from 

 pressure, it is often flattened, and the form of the outline altered. 



The only shell in the Clinton group resembling this species is the Orthonnta curta^ from 

 which it differs in its greater proportional height, and from the hinge-line being less straight. 



Fig. 3 a. A young individual of this species. 



Pig. 3 h, c. The right valves of two individuals of medium size. 



Fig. 3 d. The left valve of an older individual. 



Fig 4 a. This individual has nearly the same form as figs. 3 h and 3 c, but is more compressed, 



and the concentric folds are not at all conspicuous. I am unable to find any characters, 



however, indicating a specific distinction. 



Position and locality. In the upper gray sandstone of the Clinton group, south of Mohawk 

 village, Herkimer county. 



499. 9. TELLINOM Y A ELLIPTIC A (;i. 5^5.). 



Pl. XXX. Fig. 4 6. 



Elliptical ; extremities nearly equal ; beak scarcely prominent ; surface convex, without any 

 distinctive elevations, marked by fine concentric stria3. 



This species approaches Tellinomya curta of the preceding plate 27 ; but the extremities 

 are more nearly equal, and the beak more nearly central than in that species. The surface is 

 similarly maiked by fine concentric strise, though of these the species under consideration 

 scarcely preserves any remains. 



Position and locality. In the upper gray sandstone of the group south of Mohawk village, 

 Herkimer county. 



Pl. XXX. Fig. 5 a, b. 



Shell with both valves closed, elongate, sub-cordate ; umbones very prominent and some- 

 what gibbous below, becoming narrow and thin towards the posterior extremity ; anterior 

 extremity very short ; surface of the cast preserving very slight traces of concentric striae. 



This species is readily recognized by its gibbous anterior below the beaks, and by its 

 elongate-cordate form when both valves are closed. The specimen figured is somewhat crushed, 

 so that its entire characters are not preserved. 



Fig. 5 a. View looking upon the cardinal line. 



Fig. 5 t). Lateral view of left valve, which is crushed, showing the outline of the right valve 

 beyond. 



Podtion and locality. In the upper gray sandstone of the group, south of Mohawk village, 

 Herkimer county. 



