Natural History. 381 



ral and the ventral fins ni'e of a middling size ; the latter placed 

 about the middle of the belly, opposite to the dorsal ; at their 

 base, and along their insertion, there is a fleshy fringe, somewhat 

 similar to the long scales which are found on the most part of the 

 Clupese. The caudal fin is attai^hed to a very fleshy root, and is 

 moved by very powerful muscles. 



This elastic spring is to these fishes a most powerful lever; when 

 wishing to leap to a great height, they strike the surface of the 

 water with a kind of double stroke. By this means they overcome 

 obstacles which appear insui'mountable, and . leap over nets which 

 are intended to confine them. The most formidable waterfalls can 

 scarcely arrest them. The several species of this genus are found 

 in the northern and temperate regions of Europe, Asia, and Ame- 

 rica. 



The fishes of this family are very ravenous, and feed principally 

 upon the larvae of aquatic and other insects, and of the small Crus- 

 tacea ; they also devour fishes of a smaller size. Their alimentary 

 canal is short, but the stomach is proportionally long and strait. 

 At its pyloric extremity may be observed a great number of ap- 

 |)endices, which are connected with the pancreas, and to which is 

 generally, but erroneously, applied the name of csecum. The 

 swimming-bladder of the whole of them is very large, and opens in- 

 to the oesophagus near the bottom of the gullet. Though I cannot 

 here enter into the subject very fully, I may in a word stat9, that I am 

 persuaded that this organ ought to be regarded as the lungs of fishes ; 

 — that the circulation of the blood in these animals has been in- 

 accurately interpreted, when it is supposed that in their heart there 

 may be traced a pulmonary course ; also, when their branchise have 

 been identified with the lungs of other animals ; and. finally, when 

 their great dorsal artery has been considered as analogous to the 

 aorta of the mammalia. 



Most of the salmon varieties reside in fresh waters ; in summer 

 they pay a visit to the sea, and do not mount up again to the rivers, 

 unless for the purpose of there depositing their spawn. It is suffi- 

 ciently remarkable that most of our species deposit their ova in 

 November and December, and that the young fry of course comes 

 into existence in the coldest season of the year. From this cir- 

 cumstance we may suppose that it is owing to this habit of endur- 

 ing intense cold in the first days of their existence, that they can 

 subsequently support all that variety of temperature to which they 

 are soon to be exposed. 



VOL. XVII. NO. XXXIV. OCTOBER 1834. C C 



