42 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Juiie 14, 



cess, which very closely resembles the correspondmg part in the 

 Sloths, and especially that of the extinct colossal Edentata — the My- 

 lodons. The dental canal is very large, and the number and size of 

 the vascular foramina sent off from it, and opening on the outer sur- 

 face of the lower jaw, and along the symphysis, indicate the great 

 development of the lower lip, and of the soft parts and integuments 

 that invested the jaw. 



The physiological inferences suggested by this configuration of the 

 dentary bone are in perfect harmony with those derived from the 

 structure of the teeth, and we have now unquestionable proof that 

 the Iguanodon, like the colossal Edentata, possessed a large prehen- 

 sile tongue and fleshy lips, capable of being protruded and retracted ; 

 these must have formed most eflicient instruments for seizing and 

 cropping the foliage and branches of the ferns, cycadese, and coni- 

 ferous trees, which doubtless constituted the food of this saurian re- 

 presentative and predecessor of the great herbivorous mammalia. 



The true characters of the maxillary organs of the Iguanodon 

 being thus established, I have been able to determine with more pre- 

 cision the nature of several fragments of bones, which were tempo- 

 rarily referred to that animal. The portion of a lower jaw of a small 

 lizard from Tilgate Forest, described by me in the Philosophical 

 Transactions for 1841 as probably that of a young Iguanodon, is 

 evidently subgenerically, if not generically, distinct, though clearly 

 belonging to the same remarkable family. This saurian I therefore 

 now propose to distinguish by the name of Regnosaurus"^ , to indicate 

 the district in which it was discovered ; with the specific designation 

 of Northamptoni, as a tribute of respect to the noble President of the 

 Royal Society. 



Summary. — The fauna of the Wealden, according to the present 

 state of our knowledge, comprises the following Vertebrata : — 



Fishes. — About 30 species ; of which one belongs to the Cycloid 

 order, 16 are Placoids, and 15 Ganoids. 



Reptiles. — Twelve genera of Saurians ; and there are indications 

 of four or five not yet established. 



One genus of flying reptiles — the Pterodactyle. 



Four or five genera of Chelonians. 



Of the warm-blooded Vertebrata, bones, supposed to belong to 

 Birds (PalcBornithis), are the only vestiges hitherto obtained. 



In concluding this imperfect sketch of the fauna and flora of the 

 Country of the Iguanodon, it is impossible not to indulge for an in- 

 stant in a retrospective glance at the light shed by geological researches 

 during the last quarter of a century, on the physical history of that 

 terra incognita of my early years — the Wealden district of my native 

 county ; and I will venture to affirm, that notwithstanding the in- 

 terest and importance of the organic remains that have been dis- 

 covered, the palaeontology of the fluviatile deposits of the South-east 

 of England is as yet but very imperfectly explored, and that relics 



* Sussex, the ancient kingdom of the Regni. 



