ON BRITISH FOSSIL REPTILES. 121 



After noticing the ordinary organic remains whicli characterize the sand- 

 stone of the Tilgate Forest, and his discovery, in the summer of 1822, of other 

 teeth distinguished by novel and remarkable characters, the indefatigable ex- 

 plorer of the Wealden proceeds to state*, — 



" As these teeth were distinct from any that had previously come under my 

 notice, I felt anxious to submit them to the examination of persons whose 

 knowledge and means of observation were more extensive than my own. I 

 therefore transmitted specimens to some of the most eminent naturalists in 

 this country and on the continent. But although my communications were 

 acknowledged with that candour and liberality which constantly characterizes 

 the intercourse of scientific men, yet no light was thrown upon the subject, 

 except by the illustrious Baron Cuvier, whose opinions will best appear by the 

 following extract from the correspondence with which he honoured me : — 



" ' Ces dents me sont certainement inconnues ; elles ne sont point d'un ani- 

 mal carnassier, et cependant je crois qu'elles appartiennent, vu leur peu de 

 complication, leur dentelure sur les bords, et la couche mince d'email qui les 

 revet, a I'ordre des reptiles ; a I'apparence exterieure on pourrait aussi les 

 prendre pour des dents de poissons, analogues aux tetrodons, ou aux diodons; 

 mais leur structure interieure est fort difFerente de celles-la. N'aurions-nous 

 pas ici un animal nouveau, un reptile herbivore ? et de meme qu'actuelle- 

 ment chez les mammiferes terrestres, c'est parmi les herbivores que Ton trouve 

 les especes a plus grande taille, de meme aussi chez les reptiles d'autrefois, 

 alors qu'ils etaient les seuls animaux terrestres, les plus grands d'entr'eux ne 

 se seraient-ils point nourris de vegctaux ? Une partie des grands os que vous 

 possedez appartiendrait a cet animal unique, jusqu'a present, dans son genre. 

 Le temps cowfirmera ou iwfirmera cette idee, puisqu'il est impossible qu'on ne 

 trouve pas un jour une partie de la squelette reunie a des portions de ma- 

 choires portant des dents. C'est ce dernier objet surtout qu'ij s'agit de re- 

 chercher avec le plus de perseverance.' 



" These remarks," Dr. Mantell proceeds to say, " induced me to pursue my 

 investigations with increased assiduity, but hitherto they have not been at- 

 tended with the desired success, no connected portion of the skeleton having 

 been discovered. Among the specimens lately collected, some, however, 

 were so perfect, that I resolved to avail myself of the obliging oifer of Mr. 

 Clift (to whose kindness and liberality I hold myself particularly indebted), 

 to assist me in comparing the fossil teeth with those of the recent Lacertae in 

 the Museum of the Royal College of Surgeons. The result of this examina- 

 tion proved highly satisfactory, for in an Iguana which Mr. Stutchbury had 

 prepared to present to the College, we discovered teeth possessing the form 

 and structure of the fossil specimens." 



The important difference which the fossil teeth presented in the form of 

 their grinding surface was afterwards pointed out by Cuvierf , and recognised 

 by Dr. Mantell J, and the combination of this dental distinction with the ver- 

 tebral and costal characters, which prove the Iguanodon not to have belonged 

 to the same group of Saurians as that M'hich includes the Iguana and other 

 irvodern lizards, rendered it highly desirable to ascertain, by the improved 

 modes of investigating dental structure, the actual amount of correspondence 

 between the Iguanodon and Iguana in this respect. This I have endeavoured 

 to do in my general description of the Teeth of Reptiles §, from which the 

 following account is abridged. 



* Notice on the Iguanodon, Phil. Trans. 1825. 



t Ossemens Fossiles, 1824, vol. v. part ii. p. 351. 



X Illustrations of the Geology of Sussex, 4to, 1827. 



§ Odontography, part ii. p. 249; and Transactions of the British Association, 1838. 



