136 



P. lieterostroplia, <Srt^. Aldrich; Ingalls; Lewis; Robinson. 



P. Niagareiisis, Lea. Niagara River (Lea). 



BU LINUS, Adanmn. 

 B. hypuorum, Zi/in. Aldrich; Ingalls; Lewis; Robinson. 



Subgenus ISODORA, Ehrenh. 



I. Integra, Ilald. W. G. Binney. The specimens quoted by W. 



G. B. are young of P. heterostr&pha. 



PLANORBIS, Guettard. 



P. lentus. Say. W. G. Binney, in " Land and Fresh Water 



Shells." 



Subgenus PLANORBELLA, Haldeman. 

 P. cainpannlatus. Say. Aldrich ; Ingalls ; Lewis ; Robinson. 



Subgenus HELISOMA, Swainson. 



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



H. bicarinatus, dS«?/. Aldrich; Ingalls; Lewis; Robinson. 



Subgenus MENETUS, H. & A. Adams. 

 M. exacutus, Say. Aldrich ; Ingalls ; Lewis. 



Subgenus GYRAULUS, Agassiz. 



G. deflectuSj Say. Aldrich ; Ingalls ; Lewis ; Robinson. 



G. (lilatatus, Gould. Ingalls. 



G. albus, Midler. Lewis. 



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



SEGMENTINA, Fleming. 



Subgenus PLANORBULA, Hald. 

 P. aniiigera, »S'rty. ■ Aldrich; Ingalls; Lewis; Robinson. 



