320 



BULLETIN OF THE BUREAU OF FISHERIES 



Superior; in Jioyi they are longer in Nipigon and Superior than in the other lakes 

 in quadrilaterale the races of Superior and Michigan seem to have longer ventrals 

 than the race of Lake Michigan. 



Within the species of a lake it is evident that the same sort of variation in ven- 

 tral length occurs as in pectoral length, as illustrated by the fact that the mani- 

 toulinus race of Lake Huron and the alius races of Lakes Superior and Erie have 

 longer ventrals than the artedi races of these lakes. 



The number of ventral rays does not appear to be characteristic of any species 

 The rays number from 10 to 12 in virtually all, though some more often have 10 than 

 12, and vice versa. There is also no conspicuous variation in this character within 

 a species. 



CAUDAL 



There are no satisfactory ways of measuring the caudal; and while it appears 

 that in the case of certain species this member may be more broadly forked, the 

 eye may easily be deceived by the course of other contour lines in estimating the 

 extent of the cleft. It is sufficient to point out that in no species is the tail fin con- 

 spicuously different in the extent of its development. 



ADIPOSE 



As may be seen from an examination of the Tables 17 to 101, the size of the 

 adipose is extremely variable and has little value as a systematic character. The 

 species of Coregonus seem to have a longer adipose than the species of the other 

 genera, but this character is not always distinctive. 



Caudal Peduncle 



The length of the caudal peduncle, measured from the anterior end of the base 

 of the adipose to the first caudal rays, is too variable within each species to have 

 specific value. The depth has not been measured. For an expression of the pro- 

 portion see column L/AT in Tables 17 to 101. It also appears to vary decidedly 

 within a species. The deep-bodied forms, manitoulinus and alius of Leucichthys 

 artedi (especially the former), have a shorter and relatively deeper caudal peduncle 



Flesh 



The species within a lake are quite different in their food value. In this respect 

 artedi, with its varieties, must be rated lowest and clupeajormis highest. Prosopium 

 quadrilaterale and the other species of Leucichthys are intermediate, the first nearest 

 to artedi, the last nearest to clupeaformis. 



In Lake Nipigon none of the Leucichthys are yet marketable, so it is not known 

 how much they will be esteemed. 



The quality of flesh within a species also may be variable with the environment. 

 Thus, Lake Superior whitefish may be most esteemed by some buyers, while others 

 may prefer the Lake Erie product. The differences are nowhere as great as in the 

 case of the Erie artedi, which has richer flesh than members of the species in the 

 other lakes. It regularly competed in late years with the deep-water forms of 

 Leucichthys or "chubs" of other lakes in the smoked-fish trade, and large individ- 

 uals very often are sold as whitefish. 



