3ia PALEONTOLOGY OF NEW-YORK. 



Fig. 3 a. View of the spire of a larger specimen : the last volutions are obscured. The 

 surface preserves a few obscure wrinkles. 



Fig. 3 b. Aperture of the same. 



Fig. 4. The specimen is a partial cast, preserving a small portion of the shell, and showing 

 very distinctly the volutions of the spire. 



Fig. 8. A cast of the same species. 



PLATE LVII. 

 Fig. 4. A large individual which is extremely ventricose. The specimen is silicified, and the 

 surface striae are obliterated. 



Fig. 2, Plate lXI, is possibly a spooimon of this species. 



Geological position and locality. In the Shaly limestone, and in tlie compact layers 

 of the some rock : Helderberg mountains, Schoharie, Catskill, Becraft's mountain, 

 etc. 



Platyceras gebliardi. 



Plate LVI. Fio. 5 o 6, 6, 7 & 9; and Plate LV. Fia. dab. 

 Platycera3 gebhardi : Coxrad, Annual Report of 1840, p. 206. 



" Differs from the last in having a much larger and more prominent 

 " spire, which is longitudinally carinated near the apex, and with distinct 

 " transverse undulated striae." 



Shell obliquely subovate or subglobose, somewhat gradually expanding, 

 and becoming ventricose in the last volution. Spire composed of about 

 four volutions, which are contiguous except the last one near the 

 aperture, the apex being nearly in the plane of the outer volution : 

 aperture expanded, campanulate, and sometimes with the lip reflexed. 

 Surface marked by fine transverse undulating striae, which are sometimes 

 distinctly bent backwards along a line near the dorso-lateral curvature 

 of the shell, or nearer to the middle of the summit, and rarely slightly 

 carinated along this line . In a few specimens, distinct revolving striaa 

 are seen cancellating the transverse striae. 



This species is distinguished from the last by expanding less rapidly, and being 

 less ventricose; the apex of the spire never so far below the plane of the outer 

 volution, being sometimes slightly below, on the same plane, or elevated a little 

 above the outer volution : the suture line is deeply impressed, but not canaliculate. 

 The carination mentioned by Mr. Conrad has been observed only in the specimen 

 which he had under examination; though a similar bending backwards of the stride 

 is noticed on other specimens, indicating a notch in the labrum, which aj)pcars to 

 have been more conspicuous in the young shells than in the mature specimens. 



