Plat. 



674 



Platyceras nebrascense. (Meek. Nebrask. Q. 8. Survey, 



1872, p. 227, plate 4, fig. 15 a, 5.) Collett's Indiana Et. 1883, 

 page 159, plate 32, figs. 15, 16, natural size^ opposite sides of a 

 specimen growing on a crinoidal stem. From Indiana to New 

 Mexico; Upper Coal Measures, XV. 

 Platyceras nodosum, Conrad. Annual Report of New 



York Sur., 1841. Oriskany. VII. Hall, Pal. N. Y. Vol. 3, 1859, 

 page 472, plate 115, selected figs. 3 «j, 5, c, a young specimen 

 which has kept the proper form of the shell. Other figures 

 show specimens three times as large. All the specimens are 

 casts, with sometimes impressions of the exterior. The nodes 

 or knobs are casts of depressions on the inside surface, where 

 spines projected from the outside of the shell. In nearly all 

 the larger specimens the apex is broken off leaving only the 

 large whorl or a part of it. Possibly the apex became solid in 

 later life and therefore could not have an internal cast. Found 

 at many places along the Oriskany outcrop in N. Y. — In Penn- 

 sylvania, C. E. Hall, at Marshall's Creek, Monroe Co., 00, 804- 

 41, Hamilton. VIII c. [?] 



Platyceras obliquum, Keyes. Amer. Philos. Soc. Philada. 



^^e yes 



/i.P.S. x:^v z;2 



Vol. 25, N. 128, 1888, page 242, figs. 12, 13. Sulcarh. I. XI 



