234 EXTINCT ORDERS OF REPTILES. 



tions, and these are sucli as to be suited for walking. lu 

 particular, the femur, by its head projecting freely from the 

 acetabulum, seems to claim a movement of free stepping 

 more parallel to the line of the body, and more approaching 

 to the vertical than the sprawling gait of the crocodile. The 

 large claws concur in this indication of terrestrial habits. 

 But, on the other hand, these characters are not contrary to 

 the belief that the animal may have been amphibious ; and 

 the great vertical height of the anterior part of the tail seems 

 to support this explanation, but it does not go further. For 

 the later caudal vertebrse, instead of being much compressed, 

 as in Teleosaurus, are nearly circular in the cross section, 

 and are interlocked by posterior zygapophyses, extended over 

 half or the whole length of a vertebra?. We have therefore 

 a marsh-loving or river-side animal, dwelling amidst filicine, 

 cycadaceous, and coniferous shrubs and trees full of insects 

 and small mammalia. What was its usual diet ? li ex 

 ungiic leonem, surely ex dentc cihum. We have indeed but 

 one tooth, and that small and incomplete. It resembles 

 more the tooth of Iguanodon than that of any other reptile ; 

 and for this reason it seems probable that the animal was 

 nourished by similar vegetable food which abounded in the 

 vicinity, and was not obliged to contend with Megalosaurus 

 for a scanty supply of more stimulating diet." 



Colossal as are the dimensions of Cctiosaurtis, they appear 

 to have been exceeded by species of the genus Atlantoscmrus 

 (Titanosaurus). Thus A. montanus, from the Wealden of 

 Colorado, according to Prof Marsh, " is by far the largest 

 lancl-animal yet discovered ; its dimensions being greater 

 than was supposed possible in an animal that lived and 

 moved upon the land. It was some fifty or sixty feet in 

 length, and, when erect, at least thirty feet in height. It 

 doubtless fed upon the foliage of the mountain forests, por- 

 tions of which are preserved with its remains." 



Megalosaurus is a gigantic Oolitic Eeptile, which occurs 

 also in the Cretaceous series (Weald Clay). Its length has 

 been estimated at between forty and fifty feet, the femur and 

 tibia each measuring about three feet in length. As the 

 head of the femur is set on nearly at right angles with the 



