CONTRIBUTIONS TO PALEONTOLOGY. 5/ 



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

 at Hamilton in Madison county, N.Y. 



BELLEROPHON PATULUS. 



Bellerophon patulus : Hall, Geol. Report 4th District New-York, 1843, p. 196, f. 1. 



Shell subglobose, ventricose : umbiHcus small ; volutions rounded, 

 the last one near the aperture abruptly and widely dilated, over- 

 lapping the volution on the posterior side. The upper part of the 

 last volution is marked on the back, and partially upon the sides, 

 by strong, even, arching strise, which are more abruptly bent on 

 the dorsal line. These strise become obsolete on the middle and 

 lower sides of the volution and upon the broad expansion towards 

 the aperture, which is marked only by fine striae of grow^th ; and 

 these are sometimes a little more crowded, giving an undulating 

 surface. Anterior margin of the peristome with a broad shallow 

 sinuosity at the upper side of the last volution : some revolving 

 strise are observed crossing the others. 

 Nearly all the specimens examined are more strongly striate on 



the back of the volution above the expansion, than the one figured 



in the Geological Report of the Fourth District, but in other respects 



there is no important difference. 



The aperture in the transverse diameter measures a little more 



than one inch and five-eighths, and in the longitudinal direction one 



inch and a quarter. Another specimen has a diameter of aperture 



of nearly two inches. 



Geological formation and locality. In the coarse shales of the Hamilton 

 group in Schoharie county, at Hamilton in Madison county, at New-Berlin 

 and other places ; and also in the soft calcareous shales of the shore of Lake 

 Erie at Eighteen-mile creek. 



BELLEROPHON RUDIS (n.s.). 



Shell extremely ventricose; the first volutions rounded and sub- 

 globose, with a small umbilicus. The last half of the body- volution 

 is abruptly expanded, and the peristome spreading almost rec- 

 tangularly to the axis of the shell. Anterior margin of the peri- 

 stome slightly sinuous, and spreading on the posterior side over 

 the preceding volution. The upper part of the last volution is 



186L] 8 [Senate No. 116.] 



