GASTEROPODA. 95 



inch to more than an inch and a half in diameter. The casts of the younger 

 individuals are less acutely angular on the back than of the older ones. The 

 specimens present little variation in their general or special features — the 

 younger specimens usually preserving the distinct fascicles of fine striae, 

 separated by a single slender sharp line, while in the older ones this regularity 

 is not observed and the striae become crowded in ridges, especially towards the 

 aperture. 



The species has a very limited geographical range, so far as observed no 

 specimen having been found to the west of Schoharie county. 



Formation and localities. In the Schoharie grit, and in the Upper Helderberg 

 limestone at Schoharie, and the Helderberg mountains. A single imperfect 

 specimen has been found in the Oriskany sandstone. 



Bellerophon Pelops. 



PLATE XXII, FIGS. 7-13. 



Bellerophon (Bucania) Pelops, Hall. Descriptions of New Species of Fossils, etc., p. 28. 1861. 



Fifteenth Rep. N. Y. State Cab. Nat. Hist., p. 56. 1862. 

 Bellerophon Pelops, " Illustrations of Devonian Fossils : Gasteropoda, pis. 22, 25. 1876. 



Compare B. propinquus, Mebk. Proc. Acad. Nat. Sci. Phil., p. 78. 1871. 



« " " Geol. Surv. of Ohio. Paleontology, vol. 1, p. 226, pi. 20, fig. 4, a, b. 1873. 



Shell subglobose. Body-volution ventricose and expanded at the aperture ; 

 umbilicus closed by a callus of the lip; outer lip with a moderate sinus 

 in front and broadly rounded on each side, thickened and twisted at the 

 umbilicus, with usually a thin callosity spreading over the columellar side 

 of the aperture. Aperture transverse, broadly subreniform. 



Surface marked by a slender dorsal band, which appears either as a simple 

 elevation or with sharply carinate margins; the entire surface orna- 

 mented by fine subregular striae, which, rising from the umbilical region, 

 curve gently forward, and then more directly transverse over the body of 

 the shell, bending slightly backward as they approach the dorsal carina, 

 in crossing which they make a gentle retral curve ; the striae are usually 

 stronger on the dorsal side, and fainter in the umbilical region. 



