120 PALEONTOLOGY OF NEW YORK. 



exposed part of the volution. The casts are quite smooth and even, with the 

 exception of the angular or subcarinate aspect of the dorsum upon a part of 

 the outer volution. 



The figures 9-14 of plate 25 are from gutta-percha impressions in molds of 

 the exterior of the shell. A few individuals preserve a portion of the shell, 

 sufficient to identify the surface-markings ; but by far the larger number are 

 casts of the interior, preserving some portion of the shell in a crystalline 

 condition. The figures on plate 2G illustrate the species as it occurs in casts, 

 and with the imperfectly preserved shell. A single example, of unusual size, 

 has the exterior of the shell nearly removed by maceration and solution, but 

 still preserving some of the surface-markings. The specimen, figure 19, plate 

 26, is one which has been subjected to maceration and a solution of the 

 superficial portion of the shell, leaving a smooth surface, so far as the ordinary 

 markings are concerned, but which has not quite the condition of a cast of the 

 interior, though scarcely differing therefrom, except in the preservation of the 

 dorsal carina. On the recurved portions of the volution some faint remains of 

 pustules are visible, and another specimen in the same association is quite 

 pustulose. 



This species occurs in the central portion of the Chemung group some w hut 

 rarely, but in the higher beds it is abundant at one or two localities. In its 

 surface characters it is quite distinct from any other species in the formations 

 under consideration, but resembles in a great degree the B. tuberculatus of Fki:- 

 ussac and d'Orbiony* 



Formation and localities. In the shaly beds of the Chemung group at Phil- 

 ipsburgh, Allegany county, N. Y., and in sandstone below the conglomerate 

 near Mansfield and Tioga in Pennsylvania ; at Howard in Steuben county, 

 and abundantly at Nichols, Tioga county, N. Y. 



* Belleropliun Uibereulatun, Fbrcssac & d'Orbig.ny. Monogr. CepbaL, pi. 8, Figs. 7-10. 



" " d'Arohiac & db Veknkcil. Rbeniab Provinces, p. 80S, pi. 28, Fig. 9. 



" Keyskkmko. P,etclini-a-lim<i, 368, *Eaf. II, "Big. 5. 



" " 8ms t ii-:vii\v;i«-k«-riti n-m.-i t i< di in Bacbaen, Ht'l. ii. S. 44. Tul'. II, Big-. 12. 



" " Sanmikiujbr. BeMebtanayatom in Bfaaaaa, S. 1S1, Tat. '2-2. FTg. :•. Ba, Bb. 



