CONTRIBUTIONS TO PALEONTOLOGY. 61 



carina, upon which the striae are acutely bent backwards and make 

 a broad curve upon the sides of the volution. The spire is small, 

 and closely incurved. 



The accidental breaking of the apex of a specimen of this species, from 

 the upper part of the Hamilton group, disclosed an extension of the lip on 

 the ventral side into the cavity of the shell, forming a septum as in the 

 typical forms of Phragmostoma. 



The shell preserves no evidence of revolving striae, and the specimen from 

 the Hamilton group presents characters similar to those represented in the 

 figure cited. 



I had originally referred this with doubt to Bellerophon expansus of 

 SowERBY, but later observations show it to be distinct. It is not improbable 

 that the species of Sowerby may prove to be a Phragmostoma, and not 

 a true Bellerophon. 



Geological for7nation and locality. In the coarser shales of the Hamilton 

 group in Chenango county, and in the shale of the Portage group at Oa- 

 shaqua creek, Genesee county, N.Y. 



GENUS CYRTOLITES (Conrad). 



CYRTOLITES? MITELLA ( n. s.). 



Shell arcuate, subovoid, making altogether about two volutions in 

 the same plane; the first volution very minute; the body-w^horl 

 rapidly expanding to the aperture, which is nearly circular with 

 the peristome scarcely spreading, obtusely but distinctly angular 

 on the dorsum; apparently not sinuate, or but slightly sinuate 

 on the peristome. 



Surface marked by regular sharply elevated transverse strise, which, 

 when partially exfoliated, give a lamellose striate surface : these 

 striae are scarcely bent in passing over the angular dorsum, and 

 do not appear to be cancellated. 



Geological formatio7i and locality. In the shales of the Hamilton group 

 at Cazenovia, Madison county, N.Y. 



CYRTOLITES PILEOLUS (n.s.). <^ /■ ^ ^ ' ^^ 

 Shell obliquely or arcuately subconical. Apex of tbe spire making 

 a single slender volution and rapidly spreading below, distinctly 

 angular on the back. Aperture nearly round, a little angular in 

 front : peristome expanded, without apparent sinus. 

 1861.] 



