92 PISCES. 



contribute to this effect. The limbs being thus of but little 

 use, are greatly reduced ; the parts analogous to the bones of 

 the arms and legs are extremely short, or even completely 

 concealed ; rays, more or less numerous, which support mem- 

 branous fins, form a rude representation of the fingers and 

 toes. The fins which correspond to the anterior extremities 

 are termed pectorals, and those which answer to the posterior 

 ones, ventrals. Other rays attached to particular bones placed 

 on or between the extremities of the spinous apophyses sup- 

 port vertical fins on the back, under the tail, and at its ex- 

 tremity, which, by being raised or lowered, increase or di- 

 minish the surface which strikes against the water. The su- 

 perior fins are called dorsal, the inferior anal, and that at the 

 end of the tail caudal. The rays are of two kinds ; some of 

 them consist of a single bony piece, usually hard and pointed, 

 sometimes flexible and elastic, divided longitudinally — these 

 are called spinous rays ; others are composed of a great num- 

 ber of small articulations, and are 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 want- 

 ing. The bone which is analogous to the scapula, is some- 

 times held among the muscles as in the higher animals, and 

 at others is attached to the spine, but most commonly it is sus- 

 pended on the cranium. The pelvis rarely adheres to the 

 spine, and very frequently, instead of being behind the abdo- 

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



The vertebriE of Fishes are united by concave surfaces 

 filled with cartilage which most generally communicate by a 

 canal excavated in the axis of the vertebraB. In most of them 

 they have long spinous processes which maintain the vertical 

 form of the body. The ribs are frequently soldered to the 

 transverse processes. 



The head varies more as to form than that of any other 

 class, notwithstanding which it almost always consists of the 

 same number of bones as is found in other oviparous animals. 



