OP CONCHOLOGY. 261 



ities of margin nearly joining, connected by a heavy callus ; 

 umbilicus moderate, deep. White variously marked with a 

 single narrow, brown band, or two bands, or broader longitu- 

 dinal and spiral patches. 



Diam. 15 — 25, height 9 — 12 mill. 



Nebraska, Washington Territory. 



Smaller than No. 1, with rougher striae, and revolving lines; 

 the umbilicus is also proportionally smaller. In some speci- 

 mens the spire is more flattened. 



4. Anguispira alternata, Say. 



Plate 4, figure 47. 



Convex, more or less elevated, obliquely elosely ridge-striated ; 

 spire slightly or considerably elevated, suture well marked ; 

 whorls 6, moderately increasing, not very convex ; body mode- 

 rate, very convex beneath, often slightly angled at the periph- 

 ery ; aperture fths circular, oblique; umbilicus large and deep, 

 exhibiting the volutions. Light corneous, variegated by ob- 

 lique irregular brown stripes or spots above and below. 



Diam. 20-25, height 8-10 mill. 



Whole country eastward of Rocky Mountains. 



Varies considerably in ornamentation, convexity of the 

 upper surface, and prominence of the rib-like striaa. 



Var. Fergusonii, Bland. Smooth, never earinated. 

 Diam. 15, height 6 mill. 



New York, New Jersey. 

 Var. alba, Tryon. Perfectly colorless. 



Maine, (Morse.) Michigan, (Currier.) 



b. Carinate. 

 5. Anguispira strigosa, Gould. 



Plate 4, fig. 49. 



Depressed orbicular, thick, striate; spire not much elevated* 

 flattened, suture impressed ; whorls 5 ; body moderately large, 

 angulate at periphery, strongly deflected at aperture; aperture 

 obliquely circular, lip very nearly continuous; umbilicus 

 wide and deep. Ash-grey to brown, with generally a faint 

 medial band, and numerous bands beneath it. 



Diam. 20-25, height 10-12 mill. 



Washington Territory, Oregon, Nebraska, N. Mexico. 



