190 PLANORBIS. 



2. PLANORBIS HORNII, Tnjon. 

 Plate 5, fig. 3, 4. 



Shell large, consisting of three convex volu- 

 tions; aperture almost orbicular, not oblique, 

 nor extending above or below the plane of the 

 whorls; labrum slightly reflected, thickened 

 within, its ends converging so as nearly to 

 connect on the parietal wall ; lines of growth 

 fine and close. Color light horn. 



Diameter 21, alt. 7 mill. 



Fort Simpson, British America. Dr. Geo. 

 H. Horn. 



Grant's Lake, California. W. M. Gabb. 



Not so depressed as the preceding, smoother, 

 the growth lines being much closer and but 

 little elevated, and very different in the form 

 of the aperture. 



(37) 



