SKELETON OF FISHES. 375 



left, which is occupied by a pulpy substance. In 

 like manner, the accordance of the other cranial 

 bones with vertebrae has been attempted to be 

 traced ; but in proportion as we recede from the 

 central parts of the spine, this correspondence is 

 less distinct, in consequence of the various degrees 

 of developement which these several elements have 

 received, in order to adapt them to particular pur- 

 poses relating to sensation, to the prehension and 

 deglutition of food, and also to aquatic respiration. 



The rest of the skeleton of fishes is extremely 

 simple. In many, as in the Ray and Tetrodon, 

 there are no ribs. When these bones exist, they 

 are articulated with the extremities of the trans- 

 verse processes of the vertebrae, of which they ap- 

 pear to be merely continuations, or appendices. 

 There is generally no sternum to which they can 

 be attached below : in a few fishes only, such as 

 the Herring and the Dory, we find rudiments of 

 this bone, consisting of a few pieces placed in a 

 line on the lower part of the trunk. 



The parts of the skeleton of fishes, which corre- 

 spond to the arms and legs of quadrupeds, are the 

 pectoral and ventral fins (marked respectively by 

 the letters p and v, in Fig. 184). The former are 

 met with, with but few exceptions, in all fishes ; 

 and they consist of a series of osseous pieces, in 

 which we may often recognise with tolerable pre- 

 cision the analogous bones composing the anterior 

 extremities of a quadruped ; namely, the scapula, 

 clavicle, humerus, ulna, and radius.* These two 



* Those anatomists who are fond of pursuing the theory of ana- 

 logies, maintain that all these bones are merely developements of 

 certain ribs, proceeding from the spine in its anterior parts. A sinii- 



