FISHES OF LAKE SttPERIOR. 297 



HURO NIGRICANS Cuv. is another species of the lower Canadian 

 lakes, which occurs also in Lake Champlain. The generic dis- 

 tinction from Grystes, does not, however, rest upon sufficient charac- 

 ters to warrant its preservation in the system of fishes ; I shall 

 therefore call it in future Crrystes nigricans. It is a very common 

 fish in some of the lakes, and highly esteemed as an article of food. 

 Throughout the lake region it is known under the name of black 

 bass , and may be seen in large numbers in the enclosure under the 

 gallery of the Cataract Hotel at Niagara. Dr. Dekay describes it 

 as Centrarckus fasciatus, although he copies also Cuvier's description 

 and figure of Huro nigricans, but without perceiving their identity. 



In the northern lakes there is only one species of true Centrarchus 

 found, the Centrarchus ceneus; but it does not occur as far north as 

 Lake Superior, though it is common in Lake Huron and the other 

 great lakes. 



COTTOIDS. 



As they have been circumscribed by Cuvier, the Cottoids consti- 

 tute a most natural family, though they contain genera apparently 

 widely distinct. Indeed, between Peristedium and Scorpsena, 

 between Pterois and Aspredophorus, between Gasterosteus and 

 Cottus, there seems to be as great a chasm as can exist in a 

 natural family ; however, they all belong to one and the same 

 natural group. P>ut in order to be satisfied that it is so, one should be 

 acquainted with the fact, that animals or plants belonging to one and 

 the same natural division, will in certain cases resemble each other 

 so closely as scarcely to allow distinct subdivisions, as, for instance, 

 the Siluridae, which, with the same features throughout so numerous 

 a family, run into various extremes of form, in which, however, 

 there is no mistaking the family likeness even in the external ap- 

 pearance ; the same is also the case among Cyprinidte or among 

 Eels. But there are others, whose relations rest upon one particular 

 combination of characters, which will, nevertheless, assume very 

 different features, though preserving throughout that common trait of 

 character. Genera belonging to such families may sometimes at 

 first sight have very little resemblance to each other, they may 



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