104 PALEONTOLOGY 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 costoo 

 become stronger and farther separated from each other, with strong revolving 

 ridges, or coarse striae coining 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 rugae 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 Phragmostoma, 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. I 



PLATK XXIV, FIG. 12. 



Bellerophon OUego, 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. 



