IthS LAND AND FRESH- WATER SHELLS OP N. A. [PART IL 



PlanorlJis lieliniaiini, Dl-xkek. — Shell discoidal, pale horn- 

 colored, subvitreous, substriate, almost smooth, shining, flattened above, 

 concave below, umbilicated on both sides ; whirls four, convex, moderately 

 increasing ; aperture per-oblique, slightly dilated, rather 

 Fig. 182. rounded, almost heart-shaped. 



Shell discoid, light horn-colored, very delicately striate, 

 almost smooth, very transparent and shining ; flat or slightly 

 convex above, below somewhat concave ; umbilicate on both 

 sides ; whirls four, rounded, slightly involute, compact, sepa- 

 rated by a somewhat deep suture ; aperture very oblique, 

 somewhat widened, irregularly rounded, almost heart-shaped. 

 Greatest diam. SJ lines, height hardly 1 line. 

 lie'manni i/ai- Vera Crtiz : Herr Prof. Liebmann, of Copenhagen. 



Specimens kindly furnished by Herr Prof. Steeustrup, of 

 Copenhagen, have a hard, firm, chalky incrustation. {Dunler.') 



Planorbis Uehmanni, Dunkek in Chemn. ed. 2, p. 59, pi. x, f. 32-34. 

 Phtnorbis cjracilentus, Gould, Pr. Bost. Soc. V, 129 (1855) ; Otia, 217. 



Romer (Texas) quotes it from Xew Braunfels. The above de- 

 scription and figure are from Chemn., ed. 2. 



Flanorhis gracilentus, Gould, appears to be identical with this 

 species. It is, at least, the same as the shells in jS'os. 81^79, 8180, 

 and 8504, which I have referred to Plan. Uehmanni after a study 

 of the description and figures copied above. Xo. 9205, from the 

 Colorado Desert, is an authentic specimen of Gould's PI. graci- 

 lentus. His description here follows, and an enlarged drawing 

 of a specimen received from him. Dr. Gould suggests its identity 

 with PI. haldemani, but the aperture of that species is cam- 

 panulate. 



Pliinorhiii gracilenttis, Gould. — Shell discoidal, compressed, white, finely 

 striated ; right side flattened ; left side moderately concave ; on each side 

 four rounded whirls, the last obtusely carinated at the peri- 

 Fig. 183. phery; aperture quite obi iqi;e,rouudedly oval. Axis ^, diam. 

 J inch. 



Found by Dr. T. H. Webb, in the great Colorado Desert 

 low lands. 



No North American species, of equal size, can be compared 

 with this well-marked, wheel-shaped species. Very small 

 specimens are like large specimens of P. deflectus. Say. A species from 

 the Nile is very similar. {Gould.) 



