ft48 PALEONTOLOGY OF NEW-YORK. 



limestone, which show this character, are the only ones yet observed. The present 

 species differs conspicuously from the Niagara species. 



Fig. 1 a. A compressed specimen, which is entire at the apex. 



In two individuals preserving the smooth apex, one of them seems to be per- 

 forated in the centre ; but this feature may be accidental. 

 Fig. 1 6. A broken specimen, which preserves the quadrangular form of the shell. 

 Fig. 1 c. Knlargement of the surface as it usually appears under a lens. 



Fig. 1 (i. An enlargement of the surface, showing the granulose transverse ridges where the 

 shell is entire. This character is rarely well preserved. 



Geological position and locality. In the shaly limestone of the Lower Helderberg 

 group : Albany and Schoharie counties. 



C'oniilaiia Imiitlaiia ( n. s.). 



Platk LXII a. Fig. 2 a, b. 



Shell elongate, very gradually tapering, sides rounded, angles somewhat 

 deeply sulcate ; centre of each side marked by a shallow longitudinal 

 impression : transverse ridges curving into the sulci of the angles, and 

 angularly bent on the middle of each side ; about eleven in the space 

 of three lines, the intermediate depressions marked by longitudinal 

 , striae which are nearly twice as many in the same distance, or eighteen 

 to twenty in the space of three lines. 



The surface of the only known specimen of this species is exfoliated, so that its 

 characters are not fully preserved. It differs from the preceding in its greater size 

 and more gradually tapering form, as well as apparent greater convexity of the 

 sides ; while the comparative features, ias shown in the transverse and longitudinal 

 striffi, are quite distinct. 



Fig. 2 a. Figure of the specimen, which is compressed. 



Fig. 2 h. An enlargement of the surface, showing the bending of the transverse ridgos^t the 

 sulcus on one of the compressed edges of the specimen, and their course across 

 the centre of one side ; with the longitudinal striae. ( The figure is enlarged in 

 the same degree as that of the preceding species.) 



Geological position and locality. In the shaly limestone of the Lower Helderberg 

 group : Schoharie county. 



