372 THE CHICAGO ACADEMY OF SCIENCES. 



be found to be common to the Greenlandian, Labradorian, Hudsonian, 

 Mackenzian, Yukonian and Alaskan regions. 



RECORDS. 

 ALASKA. 



Dall River, north of the Yukon River (Dall) ; flats near St. Michael 

 (Randolph) ; Loring, southeast Alaska, on Behm Canal (U. S. Fish Com.). 



GREENLAND. 



Near Arsut; near Davis Strait (Morch); Amaraglik (Moller; Morch) ; 

 Tunnundliarbik (Holboll; Morch; Vahl) ; Inekusk (Morelet). 



BRITISH AMERICA. 



MACKENZIE: Ft. Robinson, Great Slave Lake (Kennicott). 



UNGAVA: Fort Chimo, Ungava Bay (Dall; Turner; Whft eaves). 



YUKON: Stewart River (Dall); headwaters of the Laird River in lakes; 

 Francis and Finlayson lakes (Dawson; Whiteaves); Lewis River; headwaters 

 of the Yukon in Lakes Bennett, Marsh and Lindeman (Randolph). 



GEOLOGICAL DISTRIBUTION: Unknown. 



ECOLOGY : "The occurance of the Greenland Limnaea is exceed- 

 ingly local, thus, a species was found by Moller in a little hole between 

 the mountains opposite to the colonial buildings of Godthaab and 

 not a single specimen in any of the numerous other tanks, large or 

 small, which are found in a continuous row of nearly one mile. Mol- 

 ler tells that he took (July 30, 1840) the wormenboat over to the clay 

 bank of Kuksuk, and after much searching, at length found a tank 

 with Limncea and Pisidium,; but only single specimens were obtained, 

 as they mostly walked on the bottom so far out that it was not pos- 

 sible to reach them. Holboll found Limncea sitting on stones, even 

 when the water was covered by ice \ l / 2 inches thick." (Morch, Amer. 

 Journ. Conch., IV, p. 34). 



In Alaska, Galba vahlii is found in small lakes in stations similar 

 to those occupied by Galba pulustris. 



REMARKS: Vahlii is related to palustris, and doubtless sprang 

 from that stock, but it seems to possess specific differences. It is 

 a smaller, thinner shell, the sutures are, generally, more deeply im- 

 pressed, and the inner lip and columella lack the heavy plait of pal- 

 ustris. The body whorl is also usually more globose. A comparison 

 with shells of the same size shows that vahlii has a wider, more regu- 

 larly conic spire, a rounder body whorl, a wider and more expanded 

 inner lip and scarcely an indication of a columellar plait. The globose 

 character of the body whorl at once distinguishes vahlii from tryonii 

 as does also the shape of the inner lip. The species varies greatly in 

 form, some specimens resembling pulustris with short spire equal to 

 the aperture in length, while others are much elongated. Scalariform 

 specimens occur with the spire twice as long as the aperture and with 



