THE NAUTILUS. 



VOL. XIX. MAY, 1905. No. 1. 



NOTES ON SOME PRESS- WATER, SHELLS FROM THE YUKON TERRITORY. 



BY J. F. WHITEAVES. 



Among the zoological collections in the Museum of the Geological 

 Survey of Canada, there are a few fresh-water shells from the Yukon 

 Territory, which have not yet been reported upon, though they are 

 by no means devoid of interest to the student of the geographical 

 distribution of the mollusca. 



Most of these shells were collected by the late Dr. G. M. Dawson, 

 in 1887, at four localities, viz., from Frances Lake, at the head of 

 the Liard River ; from Finlayson Lake, between Frances Lake and 

 the Pally River ; at the Lewes River ; and from Lake Marsh or 

 " Mud Lake," one of the tributaries of the Lewes River. The re- 

 mainder were collected by Mr. Joseph Keele in 1904, from the 

 Stewart River, near Mayo River. 



The Cycladidae in these collections have been kindly determined 

 by Dr. V. Sterki, and most of the Gasteropoda by Dr. W. H. Dall. 

 The species represented in them are apparently as follows : 



PELECTPODA. 



Sphserium Walkeri Sterki. 



Frances Lake, one valve ; and Finlayson Lake, two perfect speci- 

 mens. In 1904 Mr. W. Mclnnes collected a few living shells, 

 which were referred to this species by Dr. Sterki, from the Atta- 



