xi. CETEOSAURUS HABITS OF LIFE. 293 



Seven cervical at 5 - o inches . . . . 

 Nineteen dorsal, lumbar, and sacral, at 7*5 



Forty-two caudal, at 5-5 



Head 



Total ( . . . 43 feet. 



If, instead of the crocodile, we take for comparison a monitor 

 or iguana, in which the vertebrae are more numerous, we may 

 assign 60 or 70 feet for the whole length ; and combining the two 

 results, with a preference for the first, we shall allow for a full-sized 

 fossil animal the length of 50 feet, and so justify its name of the 

 ' whale lizard. 1 Probably, when ' standing at ease/ not less than 

 ten feet in height, and of a bulk in proportion, this creature was 

 unmatched in magnitude and physical strength by any of the 

 largest inhabitants of the mesozoic land or sea. 



Did it live in the sea, in fresh waters, or on the land ? This 

 question cannot be answered, as in the case of ichthyosaurus, by 

 appeal to the accompanying organic remains ; for some of the bones 

 lie in marine deposits, others in situations markedly estuarine 

 conditions, and, out of the Oxfordshire district, in Sussex, in 

 fluviatile accumulations. 



Was it fitted to live exclusively in water? Such an idea was 

 at one time entertained in consequence of the biconcave character 

 of the caudal vertebrae, and it is often suggested by the mere 

 magnitude of the creature, which would seem to have an easier life 

 while floating in water, than when painfully lifting its huge bulk 

 and moving with slow steps along the ground. But neither of these 

 arguments is valid. 



The ancient earth was trodden by larger quadrupeds than our 

 elephant ; and the biconcave character of vertebra?, which is not 

 uniform along the column in ceteosaurus, is perhaps as much a 

 character of a geological period as of a mechanical function of life. 



Good evidence of continual life in water is yielded in the case 

 of ichthyosaurs, and other enaliosaurs, by the articulating surfaces 

 of their limb-bones ; for these, all of them to the last phalanx, have 

 that slight and indefinite adjustment of the bones, with much 

 intervening cartilage, which fits the leg to be both a flexible 

 and forcible instrument of natation, much superior to the ordinary 

 oar-blade of the boatman. 



On the contrary, in ceteosaur as well as -in megalosaur and 



