FISHES. 81 



tiou of the tongue is osseous, and frequently furnished with teeth and other 

 hard parts. 



The body in most of them is covered with scales, and none possess or- 

 gans of prehension ; the fleshy cirri of some may supply the imperfection 

 of the other organs of touch. 



In the greater number, the intermaxillary bone forms the edge of the 

 upper jaw, having behind it the maxillary, termed the labial bone {mystacc). 

 A palatine arch, composed of the palatine bones, of the two pterygoid 

 processes, the zygomatic process, the tympanum and squamous |K)rtion, 

 forms, as in Birds and Serpents, a sort of interior jaw, and furnishes be- 

 hind an articulation for the lower jaw, which generally has two bones on 

 each side ; the number of these pieces, however, is reduced in the Chon- 

 dropterygii. 



Teeth are found in their intermaxillary, maxillary, and lower jaws, in 

 the vomer, the bones of the palate, on the tongue, on the arches of the 

 branchiae, and even on the bones situated behind these arches, attached 

 like them to the hyoides, and called pharyngeal bones. 



The varieties of these combinations, as well as those of the form of the 

 teeth placed at each point, are innumerable. 



Besides the apparatus of the branchial arches, the liyoid bone is fur- 

 nished on each side with rays which support the branchial membrane. A 

 sort of lid, composed of three bony pieces, the operculum, the subopercu- 

 lum, and the interoperculum, unites with this membrane in closing the 

 great opening of the gills ; it is articulated with the tympanal bone, and 

 plays on one called the preoperculum. In many of the Chondropterygii 

 this apparatus is wanting. 



The stomach and intestines differ in size, figure, thickness, and convo- 

 lutions, as greatly as in the other classes. The pancreas, except in the 

 Chondropterygii, is replaced either by c»ca of a peculiar tissue situated 

 round the pylorus, or by the tissue itself applied to the origin of the in- 

 testine. 



The kidneys are situated along the sides of the spine, but the bladder 

 is above the rectum, and opens behind the anus and behind the orifice of 

 generation; exactly the inverse of what we find in the Mammalia. 



The testes are two enormous glands commonly termed milts; and the 

 ovaries, or roe, two sacs about the same form and size, in whose internal 

 folds are deposited the eggs. Some of the ordinary fishes copulate and 

 are viviparous ; the young fry are hatched in the ovary and issue through a 

 very short canal. The Selachians alone, besides the ovary, have long 

 oviducts which frequently open into a true uterus, and they produce either 

 living ones or eggs enveloped with a horny substance. In most Fishes, 

 however, copulation does not take place ; when the female has laid, the male 



VOL. II. G 



