404 



SPECIAL GEOLOGY. 



geological celebrity, consists of those enormous reptiles which 

 he has exhumed from the wealden.* This naturalist had 

 long been in the habit of finding bones which differed from 

 those of any known recent or extinct animal. Their charac- 

 ters were such as referred them to the reptilian type, yet 

 their enormous size seemed to preclude 

 such a supposition ; for a reptile larger 

 than an elephant was too monstrous for 

 belief. At length, the discovery of a tooth 

 (fig.283),ledhimtoconjecturetheexistence 

 of a gigantic herbivorous saurian, holding 

 the same rank among reptiles w r hich was 

 occupied by the elephant and mastodon 

 among the mammalia. The teeth are of 

 a prismatic form, with prominent ridges in 

 front and serrated edges ; the enamel is 

 FIG 283.- A worn Tooth thick before and thin behind, so as to 



ofthelguanodon. . . . 



mamtain constantly a sharp and cutting 

 edge. The structure of the grinding surface proves that 

 they are referable to a herbivorous species ; the absence of a 



FIG. 284. The Jaw and Teeth of the Iguana. 



fang, and the appearance of the base, which is not broken 

 off, but indented, show that the fang has been absorbed by 



* For a complete and highly interesting account of these researches, the 

 reader is referred to Dr. Mantell's Fossils of Tilgate Forest, and his Geology* of 

 the South-east of England. 



