OP PISHES. 29 



gy, that nature had pursued an undeviating plan, 

 with regard to the shape of the body and the po- 

 sition of the limbs of all such animals as were 

 designed to exist in water. A further discovery 

 in connexion with this, that there was a peculiari- 

 ty in the structure of the gills of fishes, fitting 

 them for different localities, led the way to- 

 wards a systematic arrangement. To Linnaeus, 

 Artedi, Shaw, and lastly, the lamented Cuvier, 

 who improved upon their labors, modern science is 

 indebted for our limited knowledge of this inter- 

 esting pursuit. 



Fishes are naturally divided into two great fam- 

 ilies, viz : the spinous and the cartilaginous. In 

 the first division, are included all that have a skel- 

 eton of bones, resembling,,in some measure, the 

 compact frame-work of land animals. They have 

 articulations approaching, in structure, the joints of 

 quadrupeds, — and there is, moreover, a firmness 

 of body, in consequence of the peculiar arrange- 

 ment of the asseous textures, and the shortness of 

 the muscles, indicating their peaceable disposition ; 

 in fine, the spinous fishes have not that organiza- 

 tion which presupposes extraordinary speed. 



On the other hand, cartilaginous fishes are so 

 constructed, that they can be distorted with impu- 

 nity. Their bones possess both elasticity and 

 flexibility. Their swallows (aesophagus) as well 



