504 



THE OCEAN WORLD. 



volume this bladder assumes, the animal can increase or diminish the 

 specific gravity of its body; that is, it can remain in equilibrium 



Fig. 342. Anatomy of the Carp. 



In", tbe branchia?, or gill openings ; c, the heart; /, the liver ; vn, swimming bladders ; ci, intestinal canal ; 

 o, the ovarium ; u, urethra ; a, anus ; o' t oviduct. 



or ascend or descend in the bosom of the waters ; it is, moreover, 

 remarked that it is very small in those species which swim at the 

 bottom of the water, and Mr. Gosse says there is some reason for 



