104 LOCOMOTION OF FISHES. 



under the common covering of the body ; such ser- 

 pents as have the rudiments of these extremities, 

 have not only the greater part of them, but often 

 the whole, so concealed ; and in no animal, in fact, 

 is the whole so completely exposed as in man. 

 Generally speaking, then, we observe the most 

 perfect structural analogy between the apparently 

 rude and insignificant pectoral fin of the fish, and 

 the upper extremity of man ; there is, indeed, a 

 point in the transition, through the various tribes 

 of animals, from the one to the other, as in the 

 case of the dolphin and other cetaceous tribes, 

 where we cannot tell whether the member may be 

 called, with more propriety, a fin, or a hand and 

 arm ; and that organ of man, so noble in form, and 

 so exquisite in structure, which is at once the 

 source of his most delicate perceptions, and the 

 instrument of his sublimest works; — that organ, 

 which is so often folded in love, or stretched in ado- 

 ration, is fundamentally the same as the coarse 

 ,flabby web which hangs from the neck of an obscure 

 fish, and serves merely to assist its course, or main- 

 tain its station in the water. In this member of 

 fishes we perceive almost as much variation of 

 form as of the tail. The usual form is that repre- 

 sented on the accompanying cut, and prevails in 

 all those possessed of swift or long-sustained mo- 

 tion; it is often proportionally elongated, and is 

 also sometimes much spread out, or broadened at 

 its tip. In a few fishes it is altogether wanting, 

 and in about an equal number it is nearly only 



