532 



THE OCEAN WORLD. 



however, of the imperfect structure of their ears, fishes are sensible 

 to the least noise. In consequence, silence is a rigorous law with 

 fishermen. 



The dimensions of the mouth and teeth are very variable in 

 fishes ; these organs are in proportion to their voracity, which in many 

 of these beings is very great. The form and development of the 

 buccal pieces are also very various. Some species are toothless, but 

 in most fishes the 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 arches, and even in 

 the back mouth, that is to say, upon the pharyngeal portions, which 

 surround the entrance to the oesophagus. 



The form of their teeth is very variable, both in arrangement and 

 position : some are in the form of an elongated cone, either straight 



Fig. 354. — Teeth of the Trout. 



f^'g- 355- — Teeth of the Gold-fish Dorada. 



or curved. When small and numerous, they are comparable to the 

 points of the cards used in carding wool or cotton. Sometimes they 

 are so slender and dense as to resemble the piles of velvet, and often, 

 from their very minute size, their presence is more easily ascertained 

 by the finger than the eye. In some members of the Salmonidas, for 

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

 ridge of the palate, which is called the vomer. On each side of 

 this is another row on the palati?ie 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 cmsh 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 



