297 



In the monitors the tail is rounder, and the transverse apophyses reach 

 much further. In, the crocodiles, the basilisks, the lizards, the stellions, 

 and in the lizard tribe in general, except the monitors, and even in the 

 cetacea, and in all the quadrupeds with a large tail, the angular bone is 

 articulated on the lower part of the joining of the vertebrae, arid is there- 

 fore common to two vertebrae. 



The monitors alone have beneath the body of each vertebra two sur- 

 faces ior its reception, as in this animal ; only the body of their vertebrae 

 being more elongated, these surfaces are on them placed more posteriorly. 

 In the fossil animal, these surfaces are near the middle. But M. Cuvier 

 observes, that he does not know any animal, in which the. angular bone 

 is united in one body with the vertebra, as it is in this, through the 

 posterior part of the tail, by which its solidity is of necessity much aug- 

 mented. 



Another character, distinguishing the fossil animal from the monitors, 

 and from others of the lizard tribe, is the sudden ceasing of the articular 

 apophyses of the vertebrae, which takes place in the middle of the back, 

 whilst, in the greater part of animals, they extend very nearly to the end 

 of the tail. 



The fu>t twenty vertebrae of the tail appear to have had no angular 

 bones attached to them ; whilst, in the crocodile and monitors, only one 

 or two vertebrae of this description exist. Hence the tail of this animal 

 must have been, in all probability, cylindrical at its base, and have en- 

 larged in a vertical direction, and become flattened, only at some distance 

 from the body, assuming the form of an oar much more than is the case 

 in the crocodile. 



Besides other differences between these vertebrae and those of the cro- 

 codiles, it is observable that those of the neck, in the fossil, do not possess 

 the two tubercles which, in the crocodile, bear the little false rib on each 

 side ; which is another proof that this animal was not a crocodile, and that 

 it possessed more liberty of moving its head from side to side. 



VOL. III. Q Q 



