NAPLES FAUNA IN WESTERN NEW YORK, PART 2 32 I 



not take on the form of tubercles as in B. maera. In younger stages of 

 this species the tuberculation is relatively finer, and the form of the shell 

 less stout than in the adult condition ; and herein is found a very close 

 approach, if not'identity of character to the species B. alutaceus F. A. 

 Roemer from the lower Upper Devonic (Hartz). In a still earlier growth 

 stage the tubercles are absent, and the surface bears only sharp concentric 

 lines in strong contrast to the ultimate ornament. The aperture is not 

 expanded, but the inner lip is so reflexed as to close the umbilicus and leave 

 a smooth callus over the early part of the final whorl. The callus, however, 

 is rather thin and is restricted to later growth, so that young shells expose 

 the tubercled surface, and in adult shells broken back the young whorls 

 usually display some evidence of tuberculation and of the slit band. 



Dimensions. An adult specimen has a diameter laterally across the 

 aperture of 24 mm and vertically of 15 mm. 



Habitat. Genesee province ; Naples subprovince. Not uncommon in 



the Styliola limestone on Canandaigua lake and at Middlesex, Yates co. A 



single specimen has been collected from the Naples shales at Plum creek, 



Himrod's, Yates co. 



Bellerophon denckmanni sp. nov. 



Plate 17, fig. 24-28 



Shell small, spire very narrow, closely enrolled, dorsal surface of whorls 

 sloping from the slit band. Final whorl rather rapidly expanding but 

 not explanate at the aperture. Inner lip. slightly reflexed, forming an 

 expansion over the whorl but not always closing the umbilicus. Slit band 

 prominent, flat, with elevated margins, specially on younger stages, not 

 crossed by concentric lines except near the aperture. Surface with con- 

 centric and revolving elevated lines ; on the early whorls only the former 

 are well defined and these are stout, subequally distant, bending back along 

 the slit band ; the revolving lines appear near the beginning of the final 

 volution, grow stronger with age, while the concentric lines become pro- 

 gressively more obscure, so that in final stages the revolving lines are most 

 conspicuous but are crossed and cancelated by the concentric lines at 

 increasing intervals. 



