a04 PALAEONTOLOGY OF NEW-YORK. 



Fig. 4. The exterior of a large cast from the same rock, probably the Platyceras expanms 

 of Conrad (Annual Report of 1841, p. 56). 



In the earlier progress of this volume, the specimens figured on Plate lxvii, from 

 the Upper Pentamerus limestone, were the only ones known to me in the Lower 

 Helderberg group. Subsequently two or three species have been obtained from 

 Becraft's mountain, one of which is figured on Plate lv. 



Htropliostylus elegans (n.s.). 



Plate LV. Fig. 1 a, b, c, d. 

 Shell obliquely ovoid. Spire short, very neatly tapering to a minute apex : 

 volutions about four, symmetrically rounded on the exterior surface ; 

 suture neatly defined, the last volution ventricose, the upper or right 

 margin of the lip much extended upon the side of the volution : aper- 

 ture obliquely oval or ovoid. Surface marked by fine equal curving striae. 



The aperture has not been observed in this species; but from its general form and 

 surface markings, I can have no doubt that its proper place is among the species of 

 this genus. 



Fig. 1 a. A Bmall specimen which is imbedded in limestone. Fig. 1 6. A larger individual. 



Fig. 1 c. A larger specimen, the surface better preserved. 



Fig. 1 d. An enlarged figure, showing more distinctly the fine stria: and form of the shell. 



Geological position and locality. In the compact beds of the shaly limestone : 

 Helderberg mountains, Schoharie, and Becraft's mountain near Hudson. 



