HELIX. 



marked with longitudinal lines of coarse, elongated, 

 squamose granules, about eight or ten on each side. 



SHELL depressed, very slightly convex on the upper 

 surface ; epidermis light greenish-yellow ; whorls five, 

 nearly flat above, protuberant and rounded on the lower 

 surface, lines of growth very minute, the outer whorl 

 expanding a little towards the aperture ; umbilicus wide 

 and deep ; aperture transverse, somewhat rounded, flat- 

 tened above by a depression of the lip near its junction 

 with the body-whorl, its edge tinged with rufous ; lip 

 slightly reflected at the base of the shell, simple above, 

 the two extremities approaching each other, and con- 

 nected by a thin callus, which covers the colurnella. 



Greatest transverse diameter one inch and a quarter. 



GEOGRAPHICAL DISTRIBUTION. Brought by Mr. 

 Nuttall, and by the U. S. Exploring Expedition, from 

 the shores of Columbia River, where it is said to be 

 common. 



REMARKS. As before remarked, I have heretofore 

 considered this shell to be identical with H. concava. Say. 

 At first sight, the difference of size and color is so strik- 

 ing, that it appears to be distinct from that ; but on 

 further examination, it is found that there is a strong 

 resemblance in every particular usually relied on in the 

 discrimination of species. The specific characters on 

 which Mr. Lea seems to have relied are the " remarka- 

 ble depression " of the upper part of the lip, and the cal- 



