298 



PALJEONTOLOGT OF NEW-TORK. 



356. 15. MODIOLOPSIS ANODONTOIDES. 



Pi_ LXXXII. Fig8. 3 o, 4, c. 



CtfprieardiUt anodontoidn. Conrad. 



— tinuala. Emmons, Geol. Report, 1S42, pag. 399, fig. 3. 



GSeneral figure subelliptical, very convex ; beak elevated, with a strong angular ridge 

 extending to the posterior basal margin ; cardinal margin nearly straight; posterior extremity 

 obliquely truncated ; base contracted just below or a little posterior to the beak ; surface 

 marked by strong concentric striae ; length a little more than twice the height. 



This species is readily recognized by its great umbonical elevation, and the prominent 

 oblique carina extending from the beak to the posterior basal extremity. Its form and 

 proportions are quite different from either of the preceding, showing that it is a distinct 

 species. It is exceedingly rare, but few individuals being known, and these, with one 

 exception, are confined to the arenaceous portions of the group. 



I have united the Cypricardites sinuata of Emmons, id. dt., with this species, regarding 

 them as identical, the difference in form being due to pressure, and the occurrence of the 

 former in soft shale, which has preserved the external markings more perfectly than in the 

 specimens from sandstone. 



Fig. 3 a. A specimen in saadstone, preserving the original form of the shell. This specimen is the 



original of C. anodontoides. 

 Fig. 3 & A specimen in soft shale, more compressed than the preceding, and consequently rounded at 



the posterior extremity. This one is the original of C. sinuata. 

 Fig. 3 «. A specimen in shale, where both valves are still adhering. This is associated with the last, 



having the same surface markings, but is less compressed, and in form like fig. 3 a. 



Position and locality. This species occurs in the lower shaly part of the group, in Rod- 

 man, and in the upper arenaceous part, at Loraine, Jefferson county. (State Collection.) 



202. 3. MODIOLOPSIS FABA. 



Pi,. LXXXII. Fig. 4, 

 Reference pag. 15S, pi. 35 of this volume. 

 This species, which is abundant in the Trenton limestone, appears more rarely in 

 the Hudson-river group. It is nevertheless often found associated with the preceding and 

 following species, both in the shaly and arenaceous portions of the group, 



356. 16. MODIOLOPSIS'? NUCULIFORMIS (n.ij9.) 



Pi.. LXXXII. Figs. 5 a, b. 



Subelliptical, length nearly once and a half the width ; beaks elevated ; cardinal margin 



a little declining posteriorly ; front rounded ; a shallow sinus extending obliquely backwards 



from the beak to the base, producing an indentation in the basal margin ; surface marked 



by concentric folds, which are undulated on the sinus. 



