THE NAUTILUS. 75 



of the specimens ; epidermis thin, a little brownish in color, and 

 appearing very minutely hirsute in some shades of light under a 

 strong pocket lens ; whorls about five, the last flatly convex not 

 descending at its termination, or very little in the largest specimens ; 

 spire depressed, very little elevated above the plane of the shell ; 

 suture distinct and well defined; aperture transversely lunar, a 

 little flattened beneath ; peristome reflected, moderately thickened, 

 with a faint, long lamellar basal deposit on its inner edge, sometimes 

 absent; parietal wall bearing a small white rather sharp-pointed 

 denticle just within the aperture and near the termination of the 

 upper lip, rarely absent; lower surface of the shell flatly convex, 

 with a deep broad umbilicus showing a portion of the penultimate 

 whorl. 



Greater diam. of the largest specimen, 15, lesser 12 mm. 

 Greater diam. of the smallest specimen, 11, lesser 9 mm. 

 Height of the largest specimen, 5 mm. 

 Height of the smallest specimen, 3 mm. 



Habitat, Salmon River Mts., Idaho. 



This interesting form belongs to a large and very variable, but 

 closely related group of shells that has a wide geographical range, 

 some of its members inhabiting every state and territory of the 

 United States, and even passing beyond its limits. The west coast 

 forms of this group revolve around Helix devius Gld., as a common 

 centre, and radiate from it in every darection, greatly but gradually 

 diminishing in size, increasing, decreasing, diminishing and varying 

 in the number, size and form of the apertural denticles, and with 

 all the imtermediate stages of a brotid open, to a closely sealed 

 umbilicus. Our new variety differs from all the other known forms 

 of this group of shells, by the combination of its very depressed 

 spire, basal lamellar deposit, and its large umbilicus. Its nearest 

 ally is variety Blandi, from which it is separated by the basal 

 deposit and larger umbilicus. 



I take much pleasure in dedicating this form to my young friend, 

 Mr. Geo. H. Clapp, of Pittsburg, Pa., an intelligent student and 

 enthusiastic collector of American land shells. 



NOTES ON SLUGS. 



BY T. D. A. COCKERELL. 



My esteemed friend, Mr. Pilsbry, in conjunction with Mr. Van- 

 atta, has favored us with the first part of a " Revision of North 



