[83] 



less numerous reddish brown revolving baiids of varying 

 width. 



Diam. 25, height 16 mill. 



Western and North-western States. 



This is one of. our most beautiful species, and is extremely 

 numerous in the region inhabited by it. A variety is occa- 

 sionally met with, having a uniform dark brown epidermis, 

 (middle figure,) and Dr. Binney mentions having seen one or 

 two specimens in which the epidermis was pure white. 



tf TImhilicus open. 



X Color mottled. 



15. Mesodon Townsendiana, Lea. 



Plate 8, figures 6—7. 



Orbicular, rather thick, with oblique, irregular, coarse striae 

 and fine revolving lines, the body whorl malleated obliquely ; 

 spire convexly conical, suture moderately impressed; whorls 

 5J, the last somewhat deflected at the aperture; aperture 

 lunate, oblique, lip white, very much thickened ; base convex, 

 umbilical region subangulate, umbilicus moderate. Yellow 

 and brown variegated by the malleations. 



Diam. 30, height 18 mill. 



Oregon. 



A smaller, more compact, more elevated, not malleated 

 shell, which, if not distinct, may be designated as variety 

 minor ; inhabits Idaho and Nebraska, (fig. 6). 



XX Unieolored. 

 § Hirsute. 



16. Mesodon Columbiana, Lea. 



Plate 8, figures 12, 13, 14. 



Depressed orbicular, covered with short close hairs arranged 

 in lozenge; spire depressed conical, suture well impressed; 

 whorls 6, the last rapidly increasing, very convex, deeply con- 

 stricted behind the lip and descending to the aperture; 

 aperture narrowly lunate, lip white, widely reflected, partly 



