[ 83 ] 



less numerous reddish brown revolving bands of varying 

 width, 



Diam. 25, height 16 mill. . _\liicL': yr^'j-iu'^Oiiti. 



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 ®r 

 two specimens in which the epidermis was pure white. 



ft Umhilieus open. 

 X Color mottled. 



15. Mesodon Townsendiana, Lea. 



Plate 8, figures 6 — 7. 



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

 and fine revolving lines, the body whorl malieated 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. 80, height 18 mill. 



Oregon. Jell 'W '"^ ''."' , 



A smaller, more compact, more elevated, not malieated 

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

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



XX Unicolored. 



§ 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 



