290 



SECOND SERIES. CIIONDROPTERYGIAN, OR 

 CARTILAGINOUS FISHES. 



We have now passed in review such members of 

 the First great series of Osseous Fishes as have 

 been found in our seas, and proceed to notice, in a 

 similar way, the Second Primary Series, named 

 by Cuvier Chondkopterygian or Cartilaginous 

 Fishes. Compared with the former, it is of very 

 limited extent, not above forty species occurring in 

 this country, and of these by far the largest projior- 

 tion belong to the great families of the Rays and 

 Sharks. In this series, in contradistinction to the 

 former, the skeleton never consists of true bone, but 

 is essentially cartilaginous, that is to say, according 

 to Cuvier s definition, no osseous fibres are formed, 

 but the calcareous matter is deposited in small 

 grains and not in threads or filaments ; thence it is 

 that there are no sutures in the cranium, which is 

 always formed of a single piece. Another of the 

 most prominent characters in this series of fishes is 

 the want of maxillary and intennaxillary bones ; or 

 rather the mere rudiments of them may be said to 

 exist under the skin, while their functions are per- 

 formed by the palatals, and sometimes even by the 

 vomer. Owing to the comparatively soft texture 

 of their skeleton, these fish seem to continue to 



