226 PETRIFACTIONS AND THEIR TEACHINGS. CHAP. III. 



These genera include the colossal crocodile-lizards of the 

 dry land of the secondary geological epochs. The most 

 remarkable peculiarity in the skeleton is the construction of 

 the sacrum, for, while in all other reptiles this key-stone of 

 the pelvis consists of but two united vertebrae, in the Dino- 

 saurians it is composed of five or six anchylosed vertebrae, the 

 neural arches of which are shifted to the interspaces between 

 the bodies of those bones, and thus great solidity and strength 

 are imparted to the pelvic arch. 



From the enormous size of the bones of these animals, their 

 remains have excited the curiosity even of the common 

 observer ; and although an exaggerated idea has been 

 generally entertained of the magnitude of the originals, yet 

 when reduced to their natural proportions by the rigorous for- 

 mula of the anatomist, their dimensions are sufficiently stupen- 

 dous to satisfy the most enthusiastic lover of the marvellous. 1 



The present section will be devoted to the consideration of 

 the structure and physiology of the colossal reptile whose 

 relics occupy nearly the whole of Wall-case (7, and which is, 

 perhaps, the most extraordinary, both in regard to its history 

 and organization, of the saurians included in the Dinosaurian 

 order the IGUANODON. 



IGUANODON. The remains of this stupendous reptile that 

 have been collected since my first discovery of a tooth in 



1 It is twenty-fire years since the publication of my " Fossils of 

 Tilgate Forest" in which are numerous figures of bones of tne Wealden 

 reptiles, previously altogether unknown. Of this work, although 

 eulogized by the illustrious CUVIER, with that kind and generous 

 bearing towards every cultivator of Palaeontology, for which he was as 

 much distinguished as for his surpassing genius, not fifty copies were 

 sold. At that time there was i;ot an articulated skeleton of a crocodile 

 in the Hunterian Museum, an! but very few skeletons of any other 

 reptiles, to which access could be had for comparison with the fossil 

 bones; and many of the latter were repeatedly taken by me to the 

 College of Surgeons without obtaining any clue, e*ven as to the place 

 they held in the skeleton. 



But now the comparative anatomist may enjoy the privilege of in- 

 specting, at his ease, the immense collections of fossil reptiles in the 

 British and other Museums, and with all the advantages which access 

 to the first anatomical Museum in the world, the Hunterian, presents 

 for the comparison of fossil with recent structures. It is, therefore, 

 greatly to be deplored, that a spirit of self-aggrandizement and jealousy 

 has exerted its baneful influence over this department of palaeontology; 

 and in consequence, there is not one young British anatomist who pur- 

 sues fossil Erpetology as a special branch of study. 



