FOSSIL REPTILES. 313 



tail more round, and the transverse apophyses prevail much 

 farther in it. 



In the crocodiles, iguanas, &c., and, in general, in all the 

 saurians, except the monitors, and even in the cetacea, and in 

 all quadrupeds with large tails, the chevron-formed bone is 

 articulated under the juncture, and is common to the two ver- 

 tebrae. The monitors alone have, under the body of their 

 vertebrae, two facets to receive it, like the fossil animal ; only, 

 the body of their vertebrae being more elongated, these facets 

 are at the hinder third part. In the fossil, where the vertebrae 

 are very short from front to rear, the facets are almost in the 

 middle. But there is no reptile known in which this bone is 

 soldered and makes body with the vertebrae, as in this one. It 

 is a character belonging to fish, and must have greatly aug- 

 mented the solidity of the tail. 



Another character which distinguishes the fossil from the 

 monitors and all the saurians, is the prompt cessation of the 

 articular apophyses of the vertebrae, which are wanting from 

 the middle of the back, while in the majority of animals they 

 predominate as far as very near the end of the tail. The dol- 

 phins exhibit this character, which, united to the shortness of 

 the bodies of the vertebrae, may have contributed to the mis- 

 take of Camper above mentioned. 



The first dorsal vertebrae have their transverse apophyses 

 short, and terminated by an oblong, gibbous facet, the direc- 

 tion of which is oblique in relation to the axis of the vertebra. 

 This facet, which supports the rib, is single; consequently, the 

 rib is attached to it by a single head. This is a character of 

 the monitors and most of the saurians, the crocodiles alone 

 excepted, in which it does not take place ; for in the neck 

 there are two tubercles on each side for each rib. In the 

 back the transverse apophyses are long, depressed, and trenchant, 

 and the anterior ones have two facets for each rib, one at the 

 anterior edge, the other at the extremity. The last three ribs 

 are the only ones which have but a single head. This, again, 

 puts the crocodile completely out of question. 



