CONTRIBUTIONS TO PALEONTOLOGY. 69 



the dorsum a little elevated and sloping abruptly on the umbilical 

 side. 



The umbilical slopes of the volution are marked by strong rounded 

 transverse strise, which are sometimes bifurcated towards the side 

 of the shell, and are crossed by a few revolving depressed lines. 

 The back of the shell is conspicuously marked by flattened re- 

 volving bands, which are crossed by less conspicuous transverse 

 strise. The dorsum is marked by a narrow depressed band, on 

 which the strise make an abrupt retral bend, indicating the si- 

 nuosity in the margin of the aperture. About halfway from the 

 dorsal line to the angular sides of the volution, commence low 

 elevations, which become strong oblique ridges or elongate nodes; 

 which are limited by the angular margin of the volutions, and 

 do not pass to the ventral region. 

 The specimen examined preserves about one and a half volutions, 



is imperfect towards the aperture, and the apex is broken ofif : it 



has had a diameter of about two inches. 



This is a strongly marked species, and readily distinguished from any 



other known to me in the upper members of the New- York series. 



Geological formation and locality. In the shales of the Chemung group* 



Chemung county, N.Y. 



aYKOCERAS (CYRTOCERAS?) SPINOSUM. 



Phragmoceras spinosum : Conrad, Ann. Rep. Palseontology New-York, 1840, p. 206. 



" Shell with two rows of foliated spines." 



This species is cited by Mr. Conrad from the Schoharie grit. A fossil 

 which I suppose to have been the one described by Mr. Conrad, has the 

 form and aspect of a Cyrtoceras with the smaller extremity broken off ; 

 and though I have not seen an entire specimen, or one making a full volu- 

 tion, yet I have little doubt, from the curvature and the proportions of the 

 parts, that it has more than one volution. The shell gradually enlarges to- 

 wards the aperture, which is not expanded beyond the general proportions 

 of the shell below. The section is broadly elliptical ; the greatest diameter, 

 in the dorso-ventral direction. Measured on the side of the shell, there are 

 about six chambers in the length of the greatest diameter. Siphuncle sub- 

 central. Surface with strong lamellose transverse strias, which, on the ventral 

 side and perhaps on other parts, are raised in undulating low bands or ridges. 

 There are two rows of lamellose nodes or ''foliated spines" on each side, 

 formed by the extension of the shell in short retral arches. 



Geological formation arid locality. In Schoharie grit : Schoharie and 

 the Helderberg mountains ; and in the same rock in Ulster county, N.Y. 

 1861.] 



