420 



THE WONDERS OF GEOLOGY. Lect. IV. 



second, a considerable portion of the skeleton has been 

 found in the greensand of the chalk formation.* 



These genera comprehend the colossal crocodile-lizards 

 of the dry land of the secondary epochs. The long bones 

 of the extremities of the two first are of colossal pro- 

 portions, and have large medullary cavities, with well 

 developed processes ; their metacarpal, metatarsal and 

 digital bones, with the exception of the ungueal phalanges, 

 (bones which support the nails or claws,) resemble those of 

 the Hippopotamus, and other large pachy dermal mammalia. f 

 A very remarkable peculiarity in the osteological cha- 

 racters of this order consists in the sacrum being made 

 up of five vertebrae, anchylosed together into a solid 

 column ; whereas in all other saurians, it is formed of but 

 two united vertebrae ; and this is accompanied by another 

 modification, for the neural arches of the vertebrae are shifted 

 to the interspaces between the bodies of those bones, and 

 thus great solidity is given to the pelvic arch. Both these 

 arrangements have an evident relation to the great size of 

 the hinder extremities of these reptiles, and the enormous 

 carcass they had to support. 



From the great magnitude of some of the bones, these 

 fossils have excited the curiosity even of the common 

 observer ; and although an exaggerated idea has been 

 generally entertained of the size of the original animals, 

 yet even when their assumed proportions are reduced 

 to their natural dimensions by the rigorous formulae of the 

 comparative anatomist, they are sufficiently colossal to 

 satisfy the most enthusiastic lover of the marvellous. Of 

 this the reader may be easily convinced, if he will visit the 



* See Medals of Creation, vol. ii. p. 729. 



f See Medals of Creation, chap, xviii. for a concise view of the 

 osteological characters of these reptiles : and Professor Owen's Report 

 on Fossil Reptiles in the Transactions of the British Association of 

 Science, for 1841, for a full consideration of the subject. 



