ORISKANY SANDSTONE. 473 



Platyceras ? 



Plate CXIII. Fia. 6. 

 The specimen is a cast, too imperfect for determination; from the sandstone at 

 Schoharie. 



Platyceras nodosum. 



Plate CXV. Fig. 1 - 6 ; and Plate CXVI. Fig. 1-4. 

 Plalycercu nodosus : Conrad, Annual Report on the Palseontology of New- York for 1841, p. 56. 



" Subfalcate, with numerous thick obtuse nodes. This is a cast in sand- 

 " stone, and the shell was probably covered with spines. Length two 

 " inches." 



The above description appears to have been drawn from a cast in which the first 

 volutions are wanting; a common condition of the specimens in the sandstone. 



Shell obliquely subovate : volutions contiguous, about two or three, very 

 rapidly expanding from the apex ; summit of the spire on a plane with, 

 or a little above, the outer volution ; aperture round. 



Surface marked by round obtuse nodes and strong interrupted or tortuous 



lamellose striae. 



All the specimens observed are casts, with sometimes the impressions of the 



exterior. The nodes indicate the places of short strong spines on the surface of the 



shell. In nearly all the larger specimens the apex is broken olf, so that a single 



volution or less is preserved. 



PLATE CXV. 



Fig. 1 a, b, & 2. Young specimens of this species, preserving about two volutions. 



Fig. 3 a, b, c. A young specimen which preserves the proper form of the shell. 



Fig. 4. A larger individual. 



Fig. 5. A larger specimen, preserving little more than a single volution. 



Fig. 6. A larger specimen of similar character with the preceding. 



It is not improbable that the apex or first volutions become solidified as the shell advances 



in age, leaving no evidence of the existence of these parts in the cast. 



PLATE CXVI. 

 Fig. 1 & 2. Casts of this species, preserving the usual form. 



Fig. 3 & 4. View of the upper and lower side of the cast of a large individual. In this 

 specimen, the nodes, either from weathering or extreme age and thiclcening of 

 the shell, are less prominent than in the preceding. 



Geological position and locality. In the Oriskany sandstone : Albany and Scho- 

 harie counties, and numerous other places in the State of New- York. 

 [ Paleontology III.] 60 



