128 



LAND AND FRESH-AVATER SHELLS OF N. A. [PART IL 



Planorhis lens is referred doubtfully to exacutus by DeKay. 

 Gould refers it to P dilatatus. I have no hesitation in i)lacing 

 it in tlie synonymy of PI. exacutus. Xo. 8508 of the collection 

 was labelled P. lens by Mr. Lea. A copy of his descri[)tion and 

 figure here follow. The Barnes P. leyilicularis and P. hrogni- 

 ar-tiana were suggested by Mr. Lea in place of the pre-occupied 

 name first published by him. 



Fig. 213. 



Planorhis lens, Lea. — Shell small, lenticular, widely Timbilicate, carinate 

 on the periphery, pellucid, horu-colored ; whirls three ; aper- 

 ture large. 



Hab. Near Cincinnati, Ohio : R. Buchanan. My cahinet, 

 and cabinets of R. Buchanan and T. G. Lea. Diam. 3-20ths, 

 length l-20th of an inch. 



This is the smallest of the Planorhes which has come under 

 my notice, and may at once be distinguished by its lenticu- 

 lar form. The specimens in my possession I owe to my brother T. G. Lea. 

 They were first pointed out to him by Mr. Buchanan. {Lea.) 



Locality. 



Ohio. 



Marietta, Ohio. 

 Milwaukee, Wis. 

 Anu Arbor, Mich. 



Yellowstone River. 



From whom received. 



S. M. Luther. 

 W. Holden. 

 I. A. Lapham. 

 W. G. Biuuey. 



Dr. F. V. Hayden. 



Cabinet series. [Lea. 

 Slarked PI. lens by I. 

 (Ltns, teste Lea.) 



SpBGExrs GYRAULUS, Agassiz. 

 Shell orbicular above, flat beneath ; whirls few, rapidly in- 



Fig. 214. 



Planorhis 

 vermicularis. 



creasing. 



H. & A. Adams use Katdilina, Stein, as a name 

 for this section, but Moquin-Tandon uses Agassiz' 

 name. I am unable to decide which should have 

 preference. 



Planor'bis Terniiciilaris, GorLn.— Shell small, 

 dome-shaped, minutely striated by growth, white (proba- 

 bly bleached by the liquor from which it was taken) ; 

 whirls four, breadth and height about equal, the last one 

 deflected near the aperture, rounded at periphery, tip 

 depressed, suture very deep, the whirls sloping towards 

 it ; base cup-shaped, exhibiting all the whirls. Aper- 

 ture exhibiting a very oblique section of a cylinder ; lip 



