Notices respecting New Books. '445 



coarse conglomerate of the Forest in the spring of 1822 * ; and we 

 have subsequently collected a most interesting series, displaying every 

 gradation of form, from the perfect tooth in the young animal to the 

 laststage, that of amere bonystump worn away by mastication. These 

 teeth are comparatively rare ; and the only locality in which they 

 have hitherto been noticed, is in the immediate vicinity of Tilgate 

 Forest ; they have not been discovered in any other part of England. 

 Their external form is so remarkable, and bears so striking a resem- 

 blance to the grinders of the herbivorous mammalia, that when the 

 tooth figured in Plate XIV. fig. 14, first came under our notice, its 

 analogy to the incisors of the rhinoceros led u.s to suspect whether the 

 depoi-it in which it was found might not be of diluvial origin. Subse- 

 quent discoveries proved that these teeth belonged to an unknown 

 herbivorous reptile ; but their structure was so extraordinary, that we 

 determined to obtain, if possible, the opinion of Baron Cuvier upon 

 the subject. We accordingly transmitted specimens to our kind friend 

 Mr. Lyellj who was then residing in Paris, and by whom they were 

 presented to that illustrious naturalist. M. Cuvier favoured us with 

 the following remarks on the fossils submitted to his examination. 

 " Ces dents me sont certainement inconnues ; elles ne sont point 

 d'un animal 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 ex- 

 terieure on pourrait aussi les prendre pour des dents de poissons ana- 

 logues aux tetrodons, ou aux diodons ; mais leur structure intericure 

 est fort difturente decelles la. N'aurions-nous pas ici un animal nou- 

 veau, un reptile herbivore? et de meme qu' actuellement chez les 

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

 especes a plusgrande taille, de meme aussi chez les reptiles d'autre- 

 fois, alors qu'ils etoient les seuls animaux terrestres, les plus grands 

 d'entr'eux ne se seraient-ils point nourris de vegetaux ? Une partie 

 des grands os que vous possidez appartiendrait a ret animal, unique 

 jusqu'a present dans son genre. Le tems confirmera ou infirmera 

 cette idee, puisqu'il est impossible qu'on ne trouve pas un jour une 

 partie du squelette reunie a des portions de machoires portant des 

 dents. Si vous pouviez obtenir deces dents adherentes encore a une 

 portion un peu considerable de machoire, je crois que I'on pourrait 

 r6sou(ire le probleme." In the second part of the fifth volume of the 

 Ossemens Fossilcs, the learned autlior figures several of these teeth, 

 and minutely describes their form and structure f. From the resem- 

 blance of the perfect specimens to the teeth of certain species of 

 Iguana, we proposed to distinguish the fossil animal by the name of 

 Igunnodon ; and a memoir on the extraordinary dcntature of the 

 original was read before the Royal Society, and honoured with a place 

 in its Transactions*. 



* Sec vol. i. p. .'54. No. 40, 41. 



+ Oss. Koss. vol. V. p. 350. 



% " Notice on the Iguanodon, a newly discovered fossil herbivorous rep- 

 tile, from the sandstone of Tilgate Forest, in Sussex." Phil. Transactionn, 

 182.5, Part I. 



The 



