FISHES. 507 



teeth are very numerous. They are sometimes attached, not alone to 

 the two jaws, but also to the palate, to the tongue, and upon the 

 interior of the branchial arch, and even in 

 the back mouth, that is to say, upon the 

 ospharyngeal, which surrounds the mouth 

 of the oesophagus. 



The form of their teeth is very variable rig. 346. Teeth of the Trout. 

 both in arrangement and position : some 



are in the form of an elongated cone, either straight or curved. 

 When small and numerous, they are com- 

 parable to the points of the cards used 

 in carding wool or cotton. Sometimes 

 they are so slender and dense as to re- 

 semble the piles of velvet, and often, 

 from their very minute size, their pre- 



J ^ Fig. 347. Teeth of the Gold-fish Dorada. 



sence is more easily ascertained by the 



finger than the eye. In some members of the Salmonidse, for instance, 

 we find a row of teeth on the bone that forms the middle ridge of the 

 palate, which is called the vornex. On each side of this is another row 

 on the palatine bones, and outside these is a third pair of rows on 

 the upper jaw-bones. Some fishes have flat teeth, with a cutting edge 

 in front of the jaws, like a true incisor ; others have them rounded or oval, 

 adapted to bruise or crush the various substances on which they feed. 



The oesophagus connected with the mouth is short in fishes ; the 

 stomach and intestines vary in form and dimensions. Digestion is very 

 rapid with these beings. Most of them feed on flesh, but there are a 

 few where the mouth is without teeth, which feed on vegetables. 



The growth of fishes is slow or very rapid, according to the abun- 

 dance of food ; they can suffer a very long fast, but in that state they 

 become diminutive in size, and finally perish of exhaustion. At certain 

 seasons an irresistible impulse brings the two sexes together. Many 

 species whose ordinary appearance is dull and unsightly now shine in 

 the most brilliant colours. The female soon after lays her eggs, the 

 number of which passes all imagination. Nature seems to have accu- 

 mulated in the body of each female myriads of eggs a wise provision, 

 which is rendered necessary by the numerous causes of destruction 

 which threaten them in their native element. The eggs, abandoned 

 by the females to the mercy of the waves, are fecundated after being 



