VI. 



FISHES OF LAKE SUPERIOR COMPARED WITH THOSE OF 

 THE OTHER GREAT CANADIAN LAKES. 



BESIDES the interest there is everywhere in studying the living 

 animals of a new country, there is a particular interest to a natural- 

 ist in ascertaining their peculiar geographical distribution, and their 

 true affinities with those of other countries. It is only by following 

 such a course, that we can hope to arrive at any exact results as to 

 their origin. In this respect the freshwater animals have a peculiar 

 interest, as from the element they inhabit, they are placed under 

 exceptional circumstances. 



Marine animals, as well as those inhabiting dry land, seem to have 

 a boundless opportunity before them to spread over large parts of the 

 earth's surface, and their locomotive powers would generally be suf- 

 ficient to carry them almost anywhere ; but they do not avail them- 

 selves of the possibility ; notwithstanding their facilities for locomo- 

 tion, they for the most part remain within very narrow limits, using 

 their liberty rather to keep within certain definite bounds. This 

 tendency of the higher animals especially, to keep within well-ascer- 

 tained limits, is perhaps the strongest evidence that there is a natural 

 connection between the external world, and the organized beings 



' O O 



living upon the present surface of our globe. The laws which regu- 

 late these relations, and those of geographical distribution in partic- 

 ular, have already been ascertained to a certain extent, and will 

 receive additional evidence from the facts recorded during our jour- 

 ney. 



The freshwater animals are placed in somewhat different circuit-, 

 stances. Their abode being circumscribed by dry land within limits 



