PISCES. 191 



rays; others are composed of a great number of small articulations, 

 and generally divided into branches at their extremity they are the 

 soft, articulated, or branched rays. 



There is as much variety among Fishes, with respect to the number 

 of limbs, as among Reptiles. Most generally there are four; some 

 have but two, and in others they are totally wanting. The bone 

 which is analogous to the scapula, is sometimes held among the 

 muscles as in the higher animals, and at others is attached to the 

 spine, but most commonly it is suspended on the cranium. The pelvis 

 rarely adheres to the spine, and very frequently, instead of being behind 

 the abdomen, is before it, and connected with the humeral apparatus. 



Besides the usual parts of the brain which are arranged as in Rep- 

 tiles one after the other, Fishes have knots or ganglions at the base of 

 their olfactory nerves. 



Their nostrils are simple cavities at the end of the muzzle almost 

 always perforated by two holes, and regularly lined by a plated pituitary 

 membrane. 



The cornea of their eye is very flat, and there is but little aqueous 

 humour, but the crystalline is very hard and almost globular. 



The sense of taste in Fishes can have but little energy, as a great 

 portion 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 

 organs of prehension; the fleshy cirri of some may supply the imper- 

 fection of the other organs of touch. 



Teeth are found in their intermaxillary, maxillary, lower jaw, vomer, 

 bones of the palate, on the tongue, on the arches of the branchiae, and 

 even on bones behind these arches, attached like them to the hyoides, 

 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 hyoid 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 sub- 

 perculum, and the interoperculum, unites Avith 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 Chondrop- 

 terygii this apparatus is wanting. 



Fishes form two distinct series, that of FISHES properly so styled, 

 and that of the CHONDROFTERYGII, otherwise called CARTILAGINOUS 

 FISHES. 



