GUELPH FAUNA IN THE STATE OF NEW YORK J I 



the volution, angular margins and the rather depressed lower side. The 

 impression of the exterior verifies the observation of Whiteaves as to the 

 external characters of this species and exhibits a nearly flat or only very 

 gently convex upper slope, a vertical carination near the base of the upper 

 whorls and a slit band, appearing as a spiral ridge which is concave on the 

 apical and convex on the umbilical side. A difference from the exterior 

 view given by Whiteaves exists in the position of the slit band, which lies 

 below the mid-hight of the last volution. In the original drawing by 

 Billings it lies at mid-hight, so that there is evidently slight variation of 

 this feature. The surface is described by Whiteaves as having been appar- 

 ently smooth ; the specimen in hand shows only faint recurving growth 

 lines on the shell fragments of the upper side of the whorls. 



lophospira Whitfield. 1886 

 Lophospira bispiralis Hall (sp.) 



Plate 10, fig. 6-9 



Pleurotomaria bispiralis Hall, Paleontology of New York. 1852. 2:348, 



pi. 84, fig. 2a, 2b 

 Pleurotomaria bispiralis Whiteaves, Paleozoic Fossils. 1895. v. 3, pt 2, 



P- 74 



This species was described from a single specimen obtained by Profes- 

 sor Hall at Gait ; and Whiteaves reports that it is not otherwise known 

 except in the reidentification of the species by Billings. The recorded 

 examples are known to be poorly preserved, but the original, which was an 

 external mold, shows quite distinctly features presented by three very good 

 examples from the Rochester localities. The original description of the 

 species is as follows : " Volutions about four or five, rapidly increasing from 

 the apex, subangular, and marked above and on one side by thin, sharp 

 carinae or spiral elevated lines." It is evident, on comparison with the 

 better material in hand, that the spiral elevated lines here referred to repre- 

 sent the narrow slit band, which is very prominent on the periphery. The 

 early whorls bear a sharp keel halfway between the suture and periphery, 

 but on the final whorl this becomes quite obsolete. Present material allows 



