PLANORBIS. 199 



13. PLANORBIS BINNEYI, Tryon. 

 Hald. Monog. p. 19, pi. 3, figs. 7—9. 



This is the Planorhis corpulentus of Halde- 

 man in part, but it is not the species published 

 under that name by Mr. Say, which I agree 

 with Mr. Binney in considering nothing but a 

 fully-developed form of PL trivolvis. Mr 

 Binney's figure 193, however, is a young PL 

 ammon. 



PL Binneyi is abundant in various localities 

 in Washington Territory and Oregon. 



14. PLANORBIS TENUIS, PIdlippi. 



Plate 6, fig. 7, 8, 9. 



Shell large, very thin, shining, very deli- 

 cately striate, pale horn or smoke-colored; 

 concave on each side, umbilicated above, 

 deeply excavated below; whorls swollen, 

 rounded, above narrow, subcarinated below 

 and rapidly increasing ; aperture sinuous, sub- 



auriculate. 



(46) 



