LOCOMOTION OF FISHES. 101 



are all supported in man by the blade-bone and 

 collar-bone, and the latter by the bones of the 

 pelvis, so there are corresponding bones, in most 

 fishes, for the support respectively of the pectoral 

 and ventral fins. It is true, the correspondence of 

 these parts in fishes and in man — the lowest and 

 the highest tribes of vertebrated animals — is so 

 obscure, that, if the comparison be made abruptly, 

 no sort of resemblance will perhaps be traced ; but 

 if we are content to follow, in our investigations, 

 the same order which Nature has followed in her 

 w^orks, and to advance, by progressive steps, from 

 the lowest to the highest links of the chain, we 

 shall at once recognize the analogy, and shall be 

 compelled to acknowledge that all the parts above- 

 mentioned, as corresponding in fishes and in man, 

 are really constructed upon the same model. The 

 analogy, however, between the pectoral fins of 

 fishes, and the anterior or upper extremities of 

 the higher classes of animals, is far more striking 

 than that between the ventral fins and the poste- 

 rior or lower extremities ; and, indeed, the ventral 

 fins are in general of a size so disproportionate to 

 that of the pectoral, and sometimes placed in so 

 unusual a situation, as on the same plane with, or 

 even nearer to the snout than the latter, that it is 

 difficult at first to reconcile ourselves to the idea 

 that they correspond to legs. It is a principle, 

 however, in tracing the correspondence between 

 the several parts of different animals, to disregard 

 altogether size and situation, as constituting no 



