GASTEROPODA. 77 



more than half an inch. Two symmetrical specimens measured have the 

 proportions of width and height as 5 to 7 and 9 to 13. The casts of the 

 interior, when well preserved, show a narrow, slightly elevated band on the 

 periphery of the outer volution. 



Formation and localities. In the soft calcareous shales of the Hamilton 

 group, on the shores of Skaneateles, Seneca, Cayuga and Canandaigua lakes ; 

 at Bellona, Yates county ; at York, Moscow and other places in the western 

 counties, and more rarely on the shore of Lake Erie. It occurs in the 

 condition of casts in Madison and Otsego counties, and in the same form in 

 Maryland and Virginia. 



Pleurotomaria capillaria. 



PLATE XX, FIGS. 18-31. 



Pleurotomaria capillaria, Co.nrad. Jour. Acad. Nat. Sci. Phil., vol. 8, p. 271, pi. 16, fig. 11. 1842. 

 " " " Hall : Descriptions of New Species of Fossils, etc., p. 17. 1S61. 



'• " " " Fifteenth Rep. N. Y. State Cab. Nat. Hist., p. 45, pi. 5, fig. 2. 1862. 



" " " " Illustrations of Devonian Fossils : Gasteropoda, pi. 20. 1876. 



The following is the description of this species, as given by Mr. Conrad, 



loc. cit. : 



" Turreted, volutions slightly angulated below the middle, with spiral cari- 

 nated lines; the second and third lines from the suture, on the upper part of 

 the volutions, more distant from each other than from the adjoining striae ; 

 upper part of the volutions very obliquely rectilinear. Surface with equal 

 sharp lines which cross the volutions obliquely." 



The fossil which I have identified with Mr. Conrad's species possesses the 



following characters : 



Shell turreted, one-fourth to one-third higher than wide. Volutions four or 

 more, somewhat rapidly increasing in size, the last one ventricose, 

 subangulated above by two or three prominent revolving carinae, and 

 rounded on the lower side. Aperture subrhomboidal. 



Surface on the upper side of the volutions marked by two or three 

 revolving carinae, with finer intermediate ones or strong striae, and all 

 are crenulated by finer distant transverse striae ; lower side of volutions 



