25 1 ! LAKE SUPERIOR. 



they are from the species which occur in the Northern lakes ; so 

 that, not only is the genus located in a peculiar continent, but the 

 individual species are also confined to special regions of this coun- 

 try, from the great Canadian lakes to the freshwaters of Florida, and 

 from the Atlantic rivers to the numerous affluents of the Mississippi. 

 New England, however, has no species, and this is the more surpris- 

 ing as they occur further north in the St. Lawrence, and further 

 south in the Delaware. 



The question now arises, how this genus of fishes stands in its 

 class ; and whether, notwithstanding their peculiarity, they may not 

 be associated with some other families. 



Before answering this question, let me insist upon another fact, 

 that, even if we take into account the nominal species of Rafinesque 

 and that beautiful species of the Northern lakes first described by 

 Dr. Richardson, the Lepidostei are only ten in number. And if we 

 introduce into the same general division, the Polypteri, we shall 

 have a natural group of fishes containing in the present creation not 

 mere than a dozen species. And even should we suppose that 

 some more relatives of that group may be discovered in the course of 

 time, we can by no means suppose that this family would ever contain 

 as large a number of species as most of the other families of the class. 

 We need only remember the innumerable species of suckers, or of 

 cat-fishes, which occur every where in our fresh waters, or the 

 various kind of perch, mackerel, codfish, &c., which swarm in the 

 ocean, and among which the new discoveries to be expected can 

 hardly be fewer than among our Lepidostei, to be satisfied that there 

 is here a remarkable contrast between these families. It is therefore 

 a fact plainly shown by this evidence, that the most natural groups 

 of animals which we discover in nature, differ widely among them- 

 selves in the number of their representatives. 



It is not less obvious, that these groups differ from each other in a 

 very unequal degree, taken as general groups or considered in the 

 isolated members of their families. 



The amount of difference which distinguishes the gar-pikes from 

 the common pickerels, or from the trouts. or from the herrings, 

 or from the suckers, is far greater, for instance, than that which dis- 

 tinguishes the pickerels from the trouts, or the trouts from the 



