§ 43. THE HYLtEOSAURUS. 435 



the difference in the computation depending chiefly on the 

 extent assigned to the tail, which in the Iguana and many 

 other lizards is much longer than the body. If the tail of 

 the fossil reptile was slender, and of the same relative pro- 

 portions as in the Iguana, the largest individual would be 

 fifty or sixty feet long ; but it is more probable, and in fact 

 almost certain, from the shortness of the bodies of the caudal 

 vertebrae, that the tail was short, and flattened in a vertical 

 direction, as in certain living reptiles — for example, the 

 Doryphorus ; in that case, the length of a full-grown Iguan- 

 odon would but little exceed thirty feet.* 



From what has been advanced we may conclude, that the 

 Iguanodon was a gigantic but inoffensive herbivorous 

 reptile, which lived on the ferns, cycadese, and coniferas, 

 that constituted the flora of the country of the Wealden, of 

 which it appears to have been the principal inhabitant. 



43. The Hyl^eosaurus, or Wealden Lizard; Plate IV. 

 — This is another reptile of the Wealden, possessing the 

 same remarkable construction of the sacrum as the Iguan- 

 odon, and which I have distinguished by a name indica- 

 tive of the geological formation in which its remains occur. 

 The first and most important specimen of the Hyheosaurus 

 was discovered in the summer of 1832, under the following 

 circumstances. 



Upon visiting a quarry in Tilgate Forest, which had 

 yielded many organic remains, I perceived in some frag- 

 ments of a large mass of calciferous grit, which had recently 

 been broken up and thrown on the road-side, traces of 

 numerous pieces of bones. I therefore collected all the 

 recognizable portions of the block, and had them conveyed 

 to my residence. Having cemented the fragments together, 

 and chiselled off the stone in which the bones were im- 

 bedded, so far as their brittle state would admit, I succeeded, 

 after much labour, in developing a considerable portion of 

 * Medals of Creation, p. 751, 

 F F 2 



