184 PALJKONTOLOOY OF NEW-YORK. 



240. 1. BELLEROPHON BILOBATUS. 



Pl. XL. Figs. 3 a,b,c,d. 



Btllerophon bilobatut. Sowerbt in Sil. Researches, 1839, pag. 643. pi. 19, 6g. 13. 

 — — Emmons, Geol. Report, 1842, pag. 392, fig. 6. 



Involute, subglobose ; height and width about equal ; aperture bilobate, large, sub- 

 reniform ; surface marked by fine stria;, which, ascending from the umbilicus, form a 

 broad arch on the side of the shell, and, bending downwards, meet in an abrupt curve on 

 the dorsal line. 



The form of this shell can be readily understood from the two figures, which are of a 

 full grown individual. The arching of the striae upon the dorsal line corresponds with the 

 sinus in the aperture. The greater number of individuals of this species are smaller than 

 the one figured. 



This species is doubtless identical with the one described by SoweRby under this name. 

 It is abundant in the Trenton limestone, occurring in almost every locality. It is unknown 

 in the Utica slate and lower part of the Hudson-river group, though in the higher part of 

 the same it is often found, and in some localities is numerous. In the last named situation, 

 it corresponds exactly with specimens in the Caradoc sandstone of Great Britain, its 

 associated fossils being precisely similar. Its occurrence in the Trenton limestone, and its 

 reappearance near the top of the Hudson-river group, show its vertical range to be greater 

 than heretofore supposed. In western localities this fossil is equally abundant, ranging 

 through the entire extent of strata of the same period. It is there, however, usually destitute 

 of the shell, and much distorted from pressure. 



Fig. 3 a. Dorsal view, showing the sinus of the aperture. 

 Fig. 3 b. Lateral view, showing the involution of the whorls. 

 Fig. 3 c, d. Two views of a smaller specimen. 



Position and locality. In the Trenton limestone at Middleville, Trenton Falls, Herkimer, 

 Turin, Watertown, Glen's Falls, Plattsburgh, and numerous other localities. 



{State Collection.) 



