lymn^im: of north America. 453 



Length. Breadth. Aperture length. Breadth. 



29.50 



20.00 



19.00 



12.00 mill. 



5 whorls. 



35.00 



27.00 



21.00 



12.50 " 



Spire broken. 



32.00 



20.00 



20.00 



12.00 " 



4 whorls. 



31.00 



19.00 



18.00 



11.00 " 



Dall, zy 2 whorls. 



41.00 



23.00 



24.00 



15.50 " 



» 4 



35.00 



27.00 



24.00 



15.60 " 



" 4 



16.00 . 



10.00 



9.50 



6.00 " 



(Juvenile.) 



13.00 



7.50 



7.50 



4.10 " 



" 



Types : Chicago Academy of Sciences, one specimen, No. 23089 ; 

 four specimens, No. 23090. Cotypes in Academy of Natural Sciences 

 of Philadelphia, No. 88434. 



Type Locality: Marsh Lake, near Dyea Valley, Yukon Terri- 

 tory. 



Animal, Jaw, Radula and Genitalia: Unknown. 



Range: (Figure 51). British Columbia north to Northern Alas- 

 ka. Randolphi is a species of the Boreal life zone including the Arctic, 

 Hudsonian and Canadian divisions. It is at present known from the 

 drainage areas of the Yukon and Fraser rivers, which places it in 

 the Alaskan, Yukonian and Columbian regions. 



RECORDS. 



Alaska and British America. 



Alaska: Nushagak River, lat. 59° N., long. 159° west (Arnheim) ; Kowak 

 River (Dall; Stoney) ; lake near Cosmos River, north of the Kowak River, 

 about lat. 68° N. (Smith. Inst.) ; Alitah Lake, Alaska Peninsula (U. S. Fish 

 Com.). 



British Columbia: Lake La Hoche, Lillooet Dist. (Dall). 



Yukon: Marsh Lake, near Dyea Valley; Lake Lindeman (Randolph); 

 Francis Lake; Finleyson Lake; Lewes River (Whiteaves). 



Geological Distribution : Unknown. 



Ecology: In Marsh Lake (Randolph). The records show that 

 this species is confined principally to lakes. Its habitat relations would 

 seem to resemble those of Galba emarginata. 



Remarks : This is a very distinct species, not easily confounded 

 with any other. It has a superficial resemblance to some forms of 

 Galba emarginata mighelsi (Binney), but the angularity of the whorls, 

 the constriction of the suture, the acute spire and the deep umbilical 

 chink easily separates it from that species. From binneyi Tryon it 

 differs in its angular whorls, constricted sutures and differently shaped 

 aperture. In fully adult specimens the inner lip becomes very broad 

 and erect and completely covers the axis, thereby obscuring the char- 

 acteristic twist of the columella; but in young specimens the axis is 



