CAIITILAGINES. GENERAL CHARACTERS. 119 



bones, or, rather, only to have them in an incipient 

 state, concealed under the skin, while their functions 

 are performed by the bones analogous to the palatine 

 arches. The gelatinous substance, which^ in other fish, 

 fills the interstices of the vertebrae^ and communicates 

 only from one to the other by a small hole, forms, 

 in many of these fish^ a cord, which threads the whole 

 body of the vertebrae, with scarcely any variation in its 

 diameter. * 



(106.) The connection of this order of fishes to the rep- 

 tiles, properly so called, is effected by means of the Elanio- 

 sauri, or the fossil genera oi Ichthyosaurus, Plesiosaurus, 

 and other swimming lizards of gigantic dimensions, 

 now extinct. M. Cuvier, without being aware of the 

 full value of his observation, confirms our theory in this 

 point, when he declares that " these cartilaginous fishes 

 approach the reptiles by the conformation of their ear 

 and of their generative organs ;" while, on the other 

 hand, to prove their affinity to the cetaceous quadrupeds, 

 it has been well observed that these latter '' lead us^ by a 

 very distinct and natural transition," to fish. ^' The vivi- 

 parous sharks, such as the basking shark {Selache max- 

 ima Cuv.), with their ear more perfectly organised than 

 that of other fishes, and their body destitute of scales, 

 the particular disposition of their fins, and their closed 

 branchiae, all indicate at what place we are to enter 

 among the fishes upon leaving the cetaceous quadru- 

 peds."! It is curious to see, by the above opinions, 

 how perfectly these two naturahsts really agree, at the 

 very time when, from a partial consideration only of 

 their theories, they would appear as opposing the views 

 of each other : both may, indeed, be said to be in part 

 right. M. Cuvier, by depending entirely on his con- 

 summate knowledge of comparative anatomy, came to 

 the determination of placing the class of fish imme- . 

 diately after that of reptiles : while Mr. MacLeay, fol- 

 lowing the simple circle of affinity in the Vertebrata, 



, * Ee^. An. 2d ei torn. ii. p. 376. f Hor. Ent. p, 272. 



I 4 



