CTICA SLATE AND HUDSON-RIVEE GEOOT. 297 



353. 13. MODIOLOPSIS CURTA (rt. 5/).). 

 Pl. LXXXI. Fig. 4 ; Pl. LXXXII. Figs. 2 a - d. 

 Compare Cypricardites curia. CoNaAD, Ann. Geol. Report, 1841, p. 53. 



Suborbicular, compressed, oblique; cardinal margin short; anterior extremity rounded, 

 posterior obliquely truncated; base curving; beak distant from the anterior extremity 

 nearly one third the length of the shell ; surface marked by concentric undulations and 

 finer stria. 



In specimens not compressed, there is an obtuse oblique carina, extending from the 

 beak to the posterior margin above the base ; but when (lie shell is compressed, this feature 

 is obliterated. The concentric fine striaj are usually obliterated when the matrix is arena- 

 ceous, and they are only indistinctly preserved in specimens from the shale. This one is 

 quite unlike either of the preceding foi-ms, and deviates widely from typical forms of the 

 genus. A single specimen preserves the mark of the anterior muscular impression. 



Plate LXXXI. 



Fig-. 4. A large individual of this species, from near Grimsby, Canada West. 



Plate LXXXII. 



Fig. 2 a. A specimen from Loraino, Jefferson county, New- York. 



Fig. 2 J. A small specimen in shale, from Rodman, Jefferson county. : 



Fig. 2 c. Figure of a small specimen from Mineral Point, Wisconsin. 



Fiff. 2 d. Cardinal view of the same. 



Position and locality. This species occurs at Loraine, in the higher shaly part of the 

 group ; in the lower part of the same in the town of Rodman ; and in a similar position 

 near Rome, Oneida county. It is found in the same group in Canada, and in a similar 

 position at Mineral Point ( Wisconsin ), and several other western localities. •. 



354. 14. MODIOLOPSIS { Species undetermined) . 



Pl. LXXXI. Fig3. 5 a, b. 



Subcylindrical, elongated, very gradually expanding from the anterior extremity ; beaks 

 subacute, near the anterior extremity ; surface smooth or with fine concentric strite. 



The specimen is imperfect at both extremities, but sufficient is preserved to show that it 

 is a distinct species. In the perfect shell the beaks extend nearly or quite as far as the Ime 

 of the anterior margin. 



Fig. 5 a. Left valve of the fragment. 5 b. Dorsal view of the same. 



Position and locality. This species is known to me only in the soft shales of Cincinnati 

 ( Ohio ) . 



[Paleontology.] 38 ' . 



: . - , . ^ t 



r. 



