FISHES. 353 



Fishes are not at all dainty in the selection of their food, and their 

 powers of digestion are adequate to the solution of every thing that 

 is endowed with life. They swallow other fishes, indifferent to the 

 dangers arising from their spines and crests ; crabs and shells have no 

 terrors for them, and remains of this strange food have been found 

 in the intestines of these fishes. They reject, however, all such 

 indigestible matters, as birds of prey reject the feathers and bones 

 of small birds which they have swallowed. 



The species that live, principally, on vegetable food, constitute a very 

 small proportion of the whole community ; they are found particu- 

 larly in the genus smaris, and in some other species which may be 

 regarded as dismem1)ered portions of this genus. 



AVe should conclude, that digestion is a veiy expeditious process in 

 fishes, and their growth depends, to a great extent, on the abundant 

 supply of nourishment ; they increase in size less rapidly in the 

 smaller fish ponds, where they are too numerous, than in the vast 

 lakes, where they find the necessary food. 



The growth of fishes which attain longevity may exceed very con- 

 siderably the ordinary limits of size ; but, with the exception of some 

 species brought up by man, we know very little about the natural 

 duration of a fish's life, and hence it may be upon a conjectiire very 

 doubtful in its foundation, that the persuasion exists, that the life of 

 a fish may be preserved for ever. The reason given for this opinion, 

 which is, that the bones of fishes do not harden as much as the bones 

 of warm blooded animals, at all events is not applicable to the greater 

 part of fishes. 



ManducaHon and the teeth in particular. 



We have already explained in the the third chapter of the Osteology, 

 the composition of the jaws of fishes, and the mode in which they per- 

 form, in concert with the hyoid apparatus and the gills, the motions 

 required in order to enable them to seize their food and to swallow it. 



We have now to speak of their teeth, by means of which their foo(f 

 is generally seized and transferred to the pharynx, or in rarer cases, 

 where this food is actually carved and ground down according to 

 various methods. 



Fishes may have teeth adherent to all the bones which envelope 

 the cavity of the mouth and pharynx : they have them to the inter- 

 maxillaries, to the maxillaries, to the palatines, to the vomer, to the 

 tongue, to the branchial arches, and to the pharyngean bones, and 

 there are some genera which have teeth in all these bones, either 

 all uniform, or different to each other ; but some or many of these 

 bones may want teeth, and there exist fish which are altogether 

 deprived of them. 



The perch for example*, has teeth dense as the pile of velvet 

 to its intermaxillaries, (No. 17); to its dentaries, (No. 34) ; to a 

 transverse band in the form of a crescent under the anterior extremity 

 of its vomer, (No. 16), to a longitudinal band in each palatine, (No. 

 22), which is even continued a short distance along the border of the 



* See pi. II and III. 



