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. galtensis, not 

 alone in size, but also (i) 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 1 from Racine Wis. and Bridgeport 111., and 



1 See N. Y. State Cab. Nat. Hist. 2oth An. Rep't, p. 364. 



