548 Memoir Sears Foundation for Marine Research 



kokwim River, Alaska; western Arctic 

 Canada southward to northern British 

 Columbia (Teslin and Kluane lakes) 

 and to Fort Smith on Slave River be- 

 tween Great Slave Lake and Lake 

 Athabasca (9: 9-10). 

 I b. Teeth vestigal or wholly lacking. 



2 a. Base of adipose fin nearly or quite as long as base of anal fin. 



Irillion Jordan 1 9 1 8 . 

 Rivers of Oregon. 

 2 b. Base of adipose fin not more than about half as long as base of anal. 



3a. A single fleshy flap on either side on snout between nasal openings; body 

 rounded; gill rakers short, knob-shaped. 



Prosopium Milner 1878. 



Round Whitefishes. 



Northern Siberia; North American Arctic 

 coasts eastward to Bathurst Inlet, Hudson 

 Bay, Ungava Bay, and Labrador Peninsula; 

 southward in the east to the Great Lakes 

 region, Quebec, northern New York, and 

 Connecticut; in the west to Washington, 

 northern Idaho, western Montana, Wyoming, 

 Utah, and Nevada. Not reported in northern 

 or western Ontario, interior Manitoba, Sas- 

 katchewan, or Alberta. 

 3b. Two fleshy flaps on either side on snout between nasal openings; body 

 laterally flattened in most; gill rakers slender, pointed. 

 4 a. Margin of upper jaw noticeably sinuous in contour, the premaxillary 

 bones wider than long; tip of upper jaw extending beyond tip of 

 lower jaw; front of snout bluntly rounded; gill rakers fewer than 28, 

 the longest not more than a third as long as lower limb of arch. 



Coregonus Linnaeus 1758, p. 549. 

 4b. Margin of upper jaw only weakly sinuous in contour, the premaxillary 

 bones longer than wide; tip of lower jaw extending at least as far as 

 tip of upper jaw; front of snout tapering; gill rakers usually more 

 than 31, the longest nearly or quite half as long as lower limb of 

 gill arch. Leucichthys^ Dybowski 1870. 



Chubs, Ciscoes, and TuUibees. 



Alaska in general; Arctic coast of Canada and Hud- 

 son Bay; North-Central Canada in general, south- 

 ward to the Great Lakes region, and to northern 

 and central New York. Not reported for Newfound- 

 land, or for northern or eastern Labrador. 



I. Walters considers Leucichthys a subgenus of Coregonus [8: 279, 281). 



