184 PALEONTOLOGY OF NEW-YORK. 
240. 1. BELLEROPHON BILOBATUS. 
Pu. XL. Figs. 3 a, b, c, d. 
Bellerophon bilobatus. SowxErsy in Sil. Researches, 1839, pag. 643, pl. 19, fig. 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 striae, which, ascending from the umbilicus, form a 
broad arch on the side of the shel!, 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 strie 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 SowrrBy 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 4. 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.) 
