NAPLES FAUNA IN WESTERN NEW YORK, PART 2 327 



Phragmostoma incisum Clarke 



Plate 16, fig. 7-17 



Bellerophon incisus Clarke, U. S. Geol. Sur. Bui. 16. 1885. p. 53 



Shell having about the proportions of Ph. natator with small con- 

 cealed spire and broadly expanded peristome. The latter however has not 

 the subcordate outline of P. natator with its sloping lateral margins, but 

 is quite regularly, elliptic transversely. The final and inner whorls also are 

 depressed on top and have a shouldered appearance, while in the allied 

 species they are more evenly convex. In early stages the shell is umbilicate, 

 but the umbilicus is covered in the final stages of volution by the reflexion 

 of the inner lip. In this species the septiform callus is even more highly 

 developed than in P. natator and has the same contour, thick medially, 

 depressed laterally, the median portion projecting conspicuously inward. 

 The slit band is narrow, well defined on the body whorl and sometimes 

 visible on earlier volutions. It makes but a relatively slight emargination 

 on the outer lip. 



Surface covered by fine, incised revolving lines, seven or eight on each 

 side of the slit band on the last whorl before apertural expansion begins. 

 These may increase in number outward and become obscure. The seam 

 itself, except in its final stage, may carry one or more of these lines. 



Habitat. Genesee province ; Naples subprovince. This species is 

 quite as abundant in localities of the soft shale about Naples and in Living- 

 ston county, in the concretions on Honeoye lake and in the Whetstone 

 gully on Conesus lake. It is also present in the Styliola limestone on 



Canandaigua lake. 



Phragmostoma cf. triliratum Hall (sp.) 



Plate 16, fig. 6 



See Bellerophon (Phragmostoma?) tricarinata Hall, Illustrations of 



Devonian Fossils. 1876. pi. 22 

 Bellerophon t r i 1 i r a t u s Hall, Paleontology of New York. 1885. v. 5, pt 2, 



p. 117, pi. 24, fig. 2, 16-19 



A single specimen of rather large size shows in part the characters of 

 this species, having the narrow, well defined slit band accompanied on either 



