?.18 PALAEONTOLOGY OF NEW-YORK. 



Platjceras cun inistriiiii ( n. s.). 



Plate LXV. Fio. S a, b. 



Bhei,!. with the spire gradually ascending : body - volution somewhat 

 spirally trilobate, from two shallow depressions along the back of the 

 shell, one on the upper and one on the lower side of the volution ; the 

 last volution free, and gradually expanding towards the aperture, which 

 is subquadrate : apex unknown. 



Sdrface ma^-ked by lamellose striae, which are strongly undulated in 

 passing oyer the longitudinal depressions in the body-volution, and ate 

 nipre strongly marked towards the aperture. Obscure remains of lon- 

 gitudinal striae are preserved on some parts of the shell. 



Fig. 3 a. The upper side of the ^ire, from which the surface is nearly all exfoliated. 

 Fig. 3 b. The posterior side, showing the form of the aperture. 



Geological position and locality. In the upper pentamerus limestone : Schoharie 

 county. 



Platjceras agreste ( n. s.). 



Plate LXV. Fia. 4, 7. 



Shell with the body-volution somewhat arcuately ovoid : apex minute ; 



the last volution spreading somewhat rapidly, rounded on the upper 



side and a little contracted below : aperture large, broadly oval ; 



peristome with a broad deep sinus on the anterior side. 

 Surface marked by close transverse lamellose striae, which are crossed 



by finer longitudinal striae. 



Fig. 7. The lower side of the specimen, showing the aperture. 



Fig. 4 is a specimen having a similar form of the body-volution, but with the apex more 

 acute. The shell on the upper part of the volution is marked by abruptly 

 undulating! longitudinal striic, and, near the base, the surface becomes roughly 

 cancellated by the two sets of striaB. 



Oeolagical potition and locality. la the upper pentamerus limestone : Carlisle, 

 Schoharie county. 



