0RISKANY FAUNA OF BECRAFT MOUNTAIN 31 



Cumberland Md. A single specimen having similar characters has 

 been observed in the Onskany of Becraft mountain, and this shows a 

 slight departure from the type in the flattening of the outer surface of 

 the body-whorl. 



Platyceras nodosum Conrad 



1892. Platyceras nodosum Clarke, op. cit. p. 412 



For figures see Paleontology of New York. v. 3, pi. 115, fig. 1-G ; 

 116, fig. 1-4 



This species, common in the Oriskany sandstone of Albany and 

 Schoharie counties, is occasionally represented in the Becraft mountain 

 fauna. 



IiAMELLIBRANCHS 



Pterinea sp. ? 



(Cf. Megambonia lamellosa Hall, Paleontology of New York. 3 : 467, pi. 109, 

 fig. 5,6) 



Large but incomplete left valves indicate the presence of a 

 species without radii but with a smooth surface showing only concen- 

 tric growth lines. One of these exposes a part of the right valve, 

 which has a depressed convex and similarly smooth surface. The out- 

 line of these shells can not be clearly made out, but they present the 

 proportions and to some degree the aspect of the species cited. 



Pterinopecten subequilateralis Hall 



PlatB 4, flg. 14 



1859. Amcula subequilateralis Hall, Paleontology of New York. 3 : 281, pi. 49, 

 fig. 6 



Prof. Hall described this species from a single valve from the Pent- 

 amerus (Coeymans) limestone in Schoharie county. The form is peculiar 

 and interesting from its subsemicircular, nearly equilateral form and its 

 smooth exterior. The original referred to was regarded as a left valve, 

 but our specimens seem to demonstrate that it is the opposite valve. 

 This right valve is convex with a long, straight hinge which makes ' 

 the greatest diameter of the shell. The anterior and posterior wings 

 are not distinctly set off from the body of the shell, but the former 

 is the larger and is defined by a deeper concavity of the surface. The 



