LOWER HELDERBERG ROCKS. 26S 



Anatina ? siniiata ( n. s.). 



Plate XLIX. Fia. B a - d. 



Shell thin, equivalve, compressed, inequilateral, subrhomboid, with the 

 posterior side much wider than the anterior ; posterior? rounded, much 

 compressed near the extremity, with a distinct shallow groove ex- 

 tending from near the beak obliquely to the postero-basal margin, and 

 a second broad groove extending from the hinge-^line, immediately 

 behind the beak, vertically to the base of the shell, each one producing 

 a slight sinuosity in the margin of the shell : umbones vertical, or not 

 perceptibly inclined to either side of the shell ; anterior cardinal slope 

 nearly flat, compressed and subalate. 



Surface concentrically marked with fine subimbricating striae, which are 

 undulated in passing over the depressed lines on the anterior side of 

 of the shell. 



This fossil, from the characters preserved, is similar to some forms of Anatina; 

 but from the imperfection of the specimens examined, its true relations cannot be 

 satisfactorily determined, and I can only refer it provisionally to this genus till we 

 shall obtain a better knowledge of its characters. It possesses external characters 

 extremely different from any other fossil which has come under my observation. 



Fig. 3 a. The right valve? of a specimen in which the two extremities are imperfect. 

 Fig. 3 6. Cardinal view of the same. ( The compression of the anterior extremity is not 

 distinctly represented.) 



Fig. 3 c. The right valve? of a specimen from which the shell is nearly exfoliated, and the 

 beaks broken off. 



Fig. 3 d. Profile view of the same. 



Geological position and locality. At the base of the Lower Helderberg group, 

 Winfield, Herkimer county. 



[ PAL.aEONT0L0OT III.] 34 



