52 ANGLING. 



particular portions of it are cartilaginous. Such 

 are the bones which form the head of the pike. 



When viewed in relation to their general struc- 

 ture, the bones of fishes, like those of other verte- 

 brated animals, are composed of an organic base 

 penetrated by earthy matter. The latter consists 

 of phosphate of lime and of magnesia, with oxide 

 of iron, supposed to be united to phosphoric acid. 

 There is also a certain portion of subcarbonate of 

 lime. The animal matter is of two kinds : the 

 one, of an azotised nature, forms the base of the 

 cartilage ; the other is fatty, in the form of a per- 

 vading oil. The cartilage of fish bones differs from 

 that of mammalia and birds, in as far as it yields 

 no gelatine when subjected to the process of boiling. 



The head, possessing many more moveable parts 

 than that of quadrupeds, is subdivisible into nu- 

 merous regions, such as the cranium, the maxillae, 

 the bones beneath the cranium, and behind the 

 jaws, and which aid the movement and suspension 

 of the latter ; the bones of the opercles, which open 

 and shut the overtures of the branchiae ; the bones, 

 almost exterior, which surround the nostrils, the 

 eye, and the temples, or which cover a portion of 

 the cheek. In the majority of fishes, the inter- 

 maxillary bone (17) forms the edge of the upper 

 jaw, and has behind it the maxillary (18), com- 

 monly called the mystax, or labial bone. A palatal 

 arch (22, &c.) constructed of many parts, consti- 

 tutes, as among birds and snakes, a kind of interior 

 jaw, and provides posteriorly an articulation to the 



