GUELPH FAUNA IN THE STATE OF NEW YORK 69 



deep furrow along the suture line. The upper slope of the early whorls is 

 moderately convex, but assumes a gently sigmoidal contour on the body 

 whorl, the upper part being gently convex, the lower concave, markedly so 

 directly above the slit band. This band forms a rather narrow groove with 

 projecting sides a little above the middle of the whorl ; on the casts it appears 

 as a quite prominent ridge, and passing on the spire a little above the suture 

 line. Periphery of whorls slightly convex, nearly vertical, umbilical surface 

 strongly convex ; umbilicus small, only about one sixth of the diameter 

 of the base of the shell ; surface marked by fine crowded growth lines, 

 which curve strongly backward at the slit band but on the under side con- 

 verge directly toward the umbilicus ; aperture not observed. 



There is no satisfactory evidence of revolving ridges on the surface. 



Dimensions. The best preserved example has a hight of 38 mm, basal 

 width of 47 mm. Another, an incrusted specimen, has a hight of 43 mm, a 

 basal width of 47 mm. 



Our Rochester material has afforded but two examples of the shell, 

 which we find to differ from the still imperfectly known P. g a 1 1 e n s i s, not 

 alone in size, but also (1) in the thick and depressed spire, (2) in the profile 

 of the whorls, which are less acute than in P. galtensis and have a dif- 

 ferent curvature of surface, (3) in the distinct umbilication of the shell, 

 Whiteaves having stated that P. galtensis is imperforate. A still 

 more depressed and broader shell of apparently this group of species is 

 P. (Eotomaria)halei Hall* from Racine Wis. and Bridgeport 111., and 



1 See N. Y. State Cab. Nat. Hist. 20th An. Rep't, p. 364. 



