OKISKANY FAUNA OF BECRAFT MOUNTAIN 35 



Actinopteria insignis sp. nov. 



Plate 4, fig. 10-13 



In form and proportions this shell resembles a young Actinopt. 

 communis, but its habit is always small and its exterior profoundly 

 cancellated. It is oblique, with large and much depressed posterior 

 wing and small but nasute anterior wing, separated from the body of 

 the shell by a broad sulcus distinctly extending to the umbo. The 

 principal radial striae are strong and rounded, each interspace bearing 

 from one to three very much smaller ones, making a more marked con- 

 trast in the size of the radii than is exhibited by the species Actin- 

 opt. communis. These lines are crossed by close concentric lam- 

 ellae cancellating the entire surface, though both series of lines are quite 

 obscure on the posterior wing. To a certain degree this shell presents 

 in miniature the characters of the species Actinopt. textilis, 

 which is mainly distinguished from its associate, Actinopt. com- 

 munis, in the stronger cancellation and interruption of the radii. 



The species is not uncommon. 



Goniophora sp. \ 



This genus is represented by an incomplete valve showing a pretty 

 strong posterior carination and quite regular concentric plications which 

 become broader posteriorly. 



Megambonia crenistriata, sp. nov. 



Plate 4, fig. 16-17 



1892. Megairibonia bellistriata Clarke, op. cit. p. 413 



Megambonia bellistriata Hall, of the Helderbergian, and 

 M. cardiiformis Hall, of the Onondaga limestone are shells in which 

 with present knowledge it is difficult to find a specific difference. The 

 Megambonia occurring in the Oriskany of Becraft mountain approxi- 

 mates this specific type, but is distinguished therefrom in the follow- 

 ing features : it is a persistently smaller shell, none of the observed 

 specimens approaching the dimensions normal to those forms ; again, 

 it is shorter and lacks the strongly ovoid contour of the others, a 

 feature specially marked in early stages, where the form was decidedly 



