-108 PALEONTOLOGY OF NEW FORK. 



In all the specimens observed the dorsum is carinate and striate, while the 

 dorso-lateral part of the body -volution, as it descends into the sinus, is often 

 smooth or obscurely striate. It is possible that in some conditions of preser- 

 vation, the carinate dorsum may not be so distinct from the body of the 

 volution as in those specimens examined ; and this feature may be represented 

 as " a very acute periphery." At the present time, I prefer to adopt the name 

 given l'V Mr. Conrad to the risk of increasing the synonymy. 



In specimens where the striae are continuous over the surface, this fossil 

 bears much resemblance to the B. Chasteli, Leveille, having a precisely 

 similar dorsal elevation, but with much finer surface striae. "Where the 

 transverse striae are interrupted, or become obscure on the sides of the 

 volution, it resembles the B. Verneuili of d'Orbigny, except in the presence of 

 the dorsal elevation. 



Formation and locality. In the shales of the Hamilton group, on the eastern 

 shore of Cayuga lake, N. Y. 



Bellerophon natator. 



PLATK XXIV, FIG. 1. 



Bellerophon expansus. Geology of N. Y. Surv. Fourth Geolog. Dist., pp. 243-4, fig. 3. 1843. 

 Not Bellerophon expanxus, Sowkrby. 



Phragmostoma natator, Hai.l. Descriptions of New Species of Fossils, etc., p. 32. 1861. 

 " Fifteenth Rep. N. V. State Cab. Nat. Hist., p. 60. 1862. 

 " " " Illustrations of Devonian Fossils, pi. 23. 1876. 



Not Phragmostoma natator. Explanations of plate 6, figs. 12-14. Fifteenth Rep. State Cab. Nat. Hist.* 



Shell with the inner volutions comparatively small, and apparently closely 

 incurved; the outer volution abruptly expanded towards the aperture, 

 which is broadly oval, with the transverse much greater than the longi- 

 tudinal diameter; the peristome broadly and deeply sinuate in front. 

 The sides of the shell are strongly undulated or wrinkled. 



Surface marked by fine concentric striae of growth, which bend abruptly 

 backward on approaching the dorsum. 



* These figures are illustrations of Phragmostoma cymbula of the age of the Hudson river group, and 

 were referred by mistake to P. natator. 



