126 



tbe uiimbQr of species, or ia representatives of adjoiaiag faunas. The 

 impression that this inter-montanic region is unfavorable to the develop- 

 ment of pulmonates also seems wrong, except in respect to the scarcity 

 of lime, to wliich cause we may probably attribute the fact that the more 

 minute forms are in large majority. 



It gives me pleasure to acknowledge ray indebtedness and tender my 

 thanks to Messrs. Thomas Bland and W. Gr. Binney, Dr. James Lewis 

 and Prof. Edward S. Morse, for much kind help and good counsel, both 

 before and after the completion of this manuscript. 



MOLI^USCA. 



Class GASTEROPODA, 

 Order PECTINIBRANCHIATA. 



Family YALYATIDiE. 

 Valvata sincera, Say. 



Lakes ; San Luis Valley . . - , 1 specimen. 



Eeported also from Salt Lake (Rempkill); inhabits the northwest ter- 

 ritory {Binney). 



Eemaeks. — My single shell was found dead upon the beach. It is 

 typical, except in size, which exceeds that of any other specimens I have 

 seen. I agree with Mr. W. G-. Binney that I have never seen " speci- 

 mens referred to this species that can easily be distinguished from ecari- 

 nate forms of V. tricar inata.''^ 



Valvata virens, Tryon. — Coeur d' Alone Lake, Montana {Hemphill). 



RISSOIDiE. 



AMNICOLINJE. 



Tryonia clatharata, Stm. — Colorado Desert, Cal. {Blalce). 

 Tryoniajprotea, Gld. — Colorado Desert, Cal. {Blalce). 



Somatogyrus isogonus VAR. subglobosus, Say. 



Lakes ; San Luis Valley 5 specimens. 



I^Torthwestern part of the Union {Say). 



Remarks. — All my specimens were dead. My time was so limited at 

 this interesting point tliat I could not search the deep water for living 

 mollusks. 



Amnicola turhiniformis, Tryon. — Crane Lake Valley and Surprise Val- 

 ley, Xortheast California {Gahb); near Fort Hall, Idaho {Beid); Truc- 

 kee, Nevada {Carlton). 



Amnicola lonf/inqua, Gld. — Colorado Desert {Blalce). 



Fluminicola Ifuttalliana, Stm. — Warm Springs, near Salt Lake, Utah 

 {Reid) ; Upper Des Chutes Elver, and Klamath Eiver, Oregon {JSfeic- 

 herry) ; Oregon and California {Stimi^son). 



