I'M 



V. \H'ivros\ro\t\iii, Sill/. Aldrirli; Inf^allH; Lowi.s; UohinHon. 



1*. NinjfiinMisis, /au. Niagara River (Lea). 



iU'IJM'S, Jd'iiiKon. 

 li. llj jinorinii, A//(/t. Alilrn;li; Ingalls; Lewi.s; liohin.son. 



SubgenuH ISOnORA, Khrcith. 



I. ilitc^rU) Iliild. W, G. Binney. The Hpecimens quoted liy W. 



G. B. are young of P. hiicroHtrophn. 



PLANORBIS, Guettard. 



P. leutllS; Say. W. G. Binney, in " Land and Krcsh Water 



Shells." 



Subgenus PLANORUELLA, IIiMeman. 

 P. cailipailulatuSj 'S'r/y. Aldridi; Ingalls ; Lewis; Robinson. 



Subgenus HELISOMA, Sioainson. 



H. trivolvis, Say. Aldrich ; Ingalls; Lewis; Robinson. 



H. bicarinatuSj >S«y. Aldrich; Ingalls; Lewis; Robinson. 



Subgenus MENETUS, U. & A. Adams. 

 M. exacutns, 5«?/. Aldrich; Ingalls; Lewis. 



Subgenus GYRAULUS, Agasdz. 



G. deflectus, Say. Aldrich ; Ingalls ; Lewis ; Robinson. 



G. dilatatns, Oould. Ingalls. 



G. albus, Midler. Lewis. 



G. parvus, ASa^/- Aldrich; Ingalls; Lewis; Robinson. 



SEGMENTINA, Fleming. 



Subgenus PLANORBULA, Uald. 

 P. armigera, 5'f'^. Aldrich; Ingalls; Lewis; Robinson. 



