250 HISTORICAL PALEONTOLOGY. 



conjectured to have commonly supported itself on its hind- 

 legs only. 



The Cetiosaur attained dimensions even greater than those 

 of the Megalosaur, one of the largest thigh-bones measuring 

 over five feet in length and a foot in diameter in the middle, 

 and the total length of the animal being probably not less than 

 fifty feet. It was originally regarded as a gigantic Crocodile, 

 but it has been shown to be a true Deinosaur. Having ob- 

 tained a magnificent series of remains of this reptile, Professor 

 Phillips has been able to determine many very interesting 

 points as to the anatomy and habits of this colossal animal, 

 the total length of which he estimates as being probably not 

 less than sixty or seventy feet. As to its mode of life, this 

 accomplished \rater remarks : — 



" Probably when ' standing at ease ' not less than ten feet 

 in height, and of a bulk in proportion, this creature was un- 

 matched 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 marked by estuarine 

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

 fluviatile accumulations. Was it fitted to live exclusively in 

 water ? Such an idea w^as at one time entertained, in conse- 

 quence 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 vertebrae, 

 which is not uniform along the column in Cetiosaurus, is per- 

 haps as much a character of a geological period as of a me- 

 chanical function of life. Good evidence of continual life in 

 water is yielded in the case of Ichthyosaurus and other Ena- 

 liosaurs, 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, w^hich 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 Cetiosaur, as well 

 as in Megalosaur and Iguanodon, all the articulations are 

 definite, and made so as to correspond to determinate move- 

 ments in particular directions, and these are such as to be 



