104 
PALAEONTOLOGY OF NEW YORK. 
regarded as an extravagant form of the same, marked by peculiar developments 
of the surface characters. In the best preserved specimen before me, the 
summit of the volution near the aperture is marked very nearly as in the more 
strongly costate forms of B. patulus; but receding from the summit the costae 
become stronger and farther separated from each other, with strong revolving 
ridges, or coarse striae coming between them. These last, though becoming 
obsolete, can be traced to the margin of the shell. The few specimens of this 
species observed show considerable variation in the external features, which 
are illustrated in figures 13, 14 and 15 of plate 24. In the broad anterior 
expansion and concentric rugm this species resembles some forms of B. triliratus 
of the Chemung group; but the absence of carinae and of the fine revolving 
striae offer a characteristic distinction. 
In the broad anterior expansion of the peristome the B. patulus and B. rudis 
resemble Piiragmostoma, to which genus, in the absence of positive knowledge 
of the interior, I had at one time doubtfully referred them. They are, 
however, true Bellerophon. 
Formation and locality. In the coarse shales of the Hamilton group, at 
Fultonham, Schoharie county, N. Y. 
Bellerophon Otsego. 
PLATE XXIV, FIG. 12. 
Bellerophon Otsego, Hall. Descriptions of New Species of Fossils, etc., p. 32. 1861. 
“ •< “ Fifteenth Rep. N. Y. State Cab. Nat. Hist., p. 60. 1862. 
“ “ “ Illustrations of Devonian Fossils: Gasteropoda, pi. 22. 1876. 
Shell rotund, subglobose; body-volution ventricose, somewhat trilobate, the 
/ 
middle much wider than the lateral lobes, gradually spreading towards 
the aperture, which apparently is moderately expanded and sinuate in 
front. The lateral lobes are separated from the central part of the 
volution by a well marked sinus, and this character, with the compara¬ 
tively wide dorsal band, limited by thin sharp striae, are characteristic 
features. 
