98 HELICEA. 



(Yellowstone Riv. Ex. Ex.) in considerable quantities 

 among the Black Hills of Nebraska Territory. 



Remarks. The shells collected were weather-worn, but 

 sufficiently fresh to show considerable variety in the dispo- 

 sition of the bands and revolving patches of coloring. 



Resembles nearly no described American species. Has 

 an elevated spire like H. Pennsylvanica Green, and some- 

 what approaches H. solitaria Say. It is, however, very 

 much smaller, has rougher strife and revolving lines ; the 

 umbilicus is different, as is also the circular aperture, with 

 nearly approaching ends like H. vittata Mull., of Ceylon. 

 There is a curious variety of H. solitaria Say, found by 

 Lieut. Bryan at Bridger's Pass, which may be compared 

 with this in size ; but the only specimen I have examined 

 has no revolving lines, and wants the characteristic aper- 

 ture. Some specimens of this species have a more flat- 

 tened spire. 



Named in honor of Dr. J. G. Cooper, of P. R. R. Survey. 



HELIX ALTERNATA Say vol. ii. p. 212, pi. xxv. 



Helix alternata Say, (Binney's ed.) pp. 6, 21, pi. 69, fig. 2. 



DeKay, N. Y. Moll. 1. c. non scabra. 



Pfeiffer, iii. 98. 



Deshayes, in Per. i. 89. 



Chemnitz, i. 181. 



Reeve, Con. Icon. No. 670, (1852). 



Billings, 1857, Canad. Nat. 2, 99, figs. 4, 5. 

 Helix scabra Chenu, Illust. tab. vi. fig. 11. 

 Helix infecia Pfeiffer, Mai. Bl. 1857, p. 86 — non Reeve. 

 Helix strongylodes ? Pfeiffer, Proc. Zool. Soc. 1864, p. 53. 

 Reeve, Con. Icon. No. 1296, (1854). 



I have specimens of this species collected from Canada 

 to Texas, and most of the intervening States. I do not 

 know of its existence in Florida. It is found plentifully in 

 the Postpleiocene of Natchez Bluff, still retaining its color. 



Helix mordax Shuttleworth will, I think, prove a variety 

 of this species. H. strongylodes is also a variety, to judge 

 from the figure T have given, (pi. 77, fig. 8,) drawn by Mr. 



