PISHES. 311 



-ders it is large, round in the fore part, and terminated be- 

 low by a sort of spine. The last caudal vertebra is how- 

 ever, more remarkable than the first. It is almost always 

 of a triangular form, flat, and placed vertically. Upon its 

 posterior . extremity it bears articular impressions, which 

 correspond to the small and delicate bones of the fin of the 

 tail. 



The number of the bones of the vertebral column in 

 -different species, being exceedingly various, suggested to 

 ARTEDI the use of this character in the separation of nearly 

 allied species. Among the species of the genus Cyprinus, 

 for example, a difference in the number of vertebras has 

 been observed to the amount of fourteen. In ascertaining 

 this character, ARTEDI recommends the greatest circumspec- 

 tion. The fish should be boiled, the fleshy parts separated, 

 and the vertebrae detached from one another, and these 

 counted two or three times in succession, to prevent mis- 

 takes. This character is of great use, as it is not liable to 

 variation, individuals of the same species exhibiting the 

 same number of vertebrae in all the stages of their growth. 



The number and size of the ribs are likewise extremely 

 various. The cartilaginous fishes may be considered as 

 destitute of true ribs. Where they exist, as in the osseous 

 fishes, they are articulated to the body of the vertebrae, or 

 to the transverse processes. They are forked in some 

 fishes, and in others double; that is, two ribs proceed from 

 each side of every vertebra. In the genus Cyprinus they 

 are of a compressed shape; in the cod they are round; 

 and in the herring, like bristles. 



The number of the ribs, likewise, furnishes a character 

 in the discrimination of species, which may be safely relied 

 on in the absence of more obvious characters. 



Besides these bones which we have enumerated, there 

 are many more osseous spiculsc, which serve to support the 

 fins, and to strengthen the muscles. 



