FISHES OF LAKE SUPERIOR. 375 



almost the whole extent of that fauna, while others appear circum- 

 scribed within very narrow limits. 



it 



Now, such differences in the range which the isolated species take 

 in the faunae is a universal character of the distribution of animals ; 

 some species of certain families covering, without distinction, exten- 

 sive grounds, which are occupied by several species of other families, 

 limited to particular districts of the same zone. 



But, after making due allowance for such variations, and taking a 

 general view of the subject, we arrive, nevertheless, at this conclu- 

 sion ; that all the freshwater fishes of the district under examination 

 are peculiar to that district, and occur nowhere else in any other 

 part of the world. 



They have their analogues in other continents, but nowhere beyond 

 the limits of the American continent do we find any fishes identical 

 with those of the district, the fauna of which we have been re- 

 cently surveying. The Lamprey eels of the lake district have very 

 close representatives in Europe, but they cannot be identified. The 

 sturgeons of this continent are neither identical with those of Europe 

 nor with those of Asia. The cat-fishes are equally different. We 

 find a similar analogy and similar differences between the perches, 

 pickerels, eelpouts, salmons, and carps. In all the families which 

 occur throughout the temperate zone, there are near relatives on the 

 two continents, but they do not belong to the same stock. And in 

 addition to these, there are also types which are either entirely peculiar 

 to the American continent, such as Lepidosteus and Percopsis, or 

 belong to genera which have not simultaneously representatives in 

 the two worlds, and are therefore more or less remote from those 

 which have such close analogues. The family of Percoids, for in- 

 stance, has several genera in Europe, which have no representatives 

 in America ; and several genera in America which have no repre- 

 sentatives in Europe, besides genera which are represented on both 

 continents, though by representatives specifically distinct. 



Such facts have an important bearing upon the history of creation, 

 and it would be very unphilosophical to adhere to any view respect- 

 ing its plan, which would not embrace these facts, and grant them 

 their full meaning. If we face the fundamental question which is at 

 the bottom of this particular distribution of animals, and ask ourselves, 



