GASTEROPODA. 113 



Bellerophon Lyra. 



PLATE XXIII, FIGS. 1, 17-20. 



Bellerophon Lyra, Hall. Descriptions of New Species of Fossils, etc., p. 31. 1861. 

 Fifteenth Rep. N. Y. State Cab. Nat. Hist., p. 59. 1862. 

 " " " Illustrations of Devonian Fossils : Gasteropoda, pi. 24. 1876. 



Shell subglobose ; moderately and evenly convex on the dorsum, the outer 

 half of the body-volution ventricose and abruptly spreading towards the 

 aperture, which is extremely expanded, round-oval, a little wider than 

 long ; peristome distinctly sinuate in front. 



Surface marked by regular, subequal, flattened, revolving strise, which are 

 sometimes bifurcated, increasing in width towards the margin. The 

 spaces between the wider striae are marked by extremely slender linear 

 strhe, which do not increase in width as the adjacent ones, and are of the 

 same strength at the margin as on the more prominent parts of the volu- 

 tion. The striae are slightly undulating, and very distinct to near the 

 aperture, where they become obsolete, or terminate in a smooth border 

 which is not thickened exteriorly. There are no marked transverse striae 

 other than the obscure lines of growth, only to be seen under a lens. 

 The dorsum is marked by an elevated, rounded carina, which is crossed 

 by prominent arching and subimbricating lamelliform striae or ridges, of 

 which there are about two or three in the space of a line. 



This species bears a close resemblance to B. Leda in some of its phases ; but 

 the shell is apparently less ventricose; the aperture is more equally, and 

 less abruptly expanded than is usual in that species, and there are no con- 

 spicuous transverse striae, while the revolving striae are broader and more equal, 

 and the dorsal band elevated into an obtuse carina with distant imbricating 

 striae. Length of aperture, in the largest specimen observed, about seven- 

 eiffhths of an inch, with a transverse diameter of an inch. 



All the specimens which can be strictly determined as of this species, are 

 from the coarser shales of the Hamilton group in Schoharie county, while 

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