and on the Fauna and Flora of the Wealden Formation. 89 



a scoop-like process, which resembles the corresponding part of the 

 inferior jaw of the Edentate mammalia, as for example the Mylo- 

 dons : and the great number and size of the vascular foramina of 

 the jaw indicate a greater development of the lips and integuments 

 than occurs in any existing animals of the class Reptilia ; the sharp 

 ridge bordering the deep groove of the symphysis, in which there 

 are likewise several foramina for the exit of nerves and bloodvessels, 

 evidently gave attachment to the muscles and integuments of the 

 lip ; while two deep pits for the insertion of the protractor muscles 

 of the tongue, manifest the mobility and power of that organ. 

 There are, therefore, strong reasons for supposing that the lips in 

 the Tguanodon were flexible, and, in conjunction with the long, fleshy, 

 prehensile tongue, were the chief instruments for seizing and crop- 

 ping the leaves, branches, and fruit, which, from the construction 

 of the teeth, we may infer constituted the food of the original. The 

 mechanism of the maxillary organs, as elucidated by recent disco- 

 veries, is thus in perfect harmony with the remarkable characters 

 which rendered the first known teeth so enigmatical ; and in the 

 Wealden herbivorous reptile we have a solution of the problem, how 

 the integrity of the type of organisation peculiar to the class of 

 cold-blooded vertebrata was maintained, and yet adapted, by simple 

 modifications, to fulfil the conditions required by the economy of a 

 gigantic terrestrial reptile, destined to obtain support from vegetable 

 substances ; in like manner as the extinct colossal herbivorous 

 Edentata, which flourished in South America, countless ages after 

 the country of the Iguanodon and its inhabitants had been swept 

 from the face of the earth. 



The structure of the cervical, dorsal, and caudal vertebrae, of the 

 ribs, the pectoral and pelvic arches, the sacrum formed of six anchy- 

 losed vertebrae, the bones of the extremities, and certain dermal 

 appendages, were successively described, and illustrated by drawings 

 and specimens. From the facts adduced Dr Mantell infers that this 

 stupendous reptile equalled in bulk the largest herbivorous mam- 

 malia, and was as massive in its proportions ; for living exclusively 

 on vegetables, the abdominal region must have been greatly de- 

 veloped. Its limbs were of proportionate size and strength, to sup- 

 port and move so enormous a carcass ; its length, as proved by re- 

 cent discoveries, was of crocodilian proportions, for there is no doubt 

 that the tail was very long ; and the largest Iguanodon may have 

 attained a length of from fifty to sixty feet. 



The HylcEosaurus, Megalosaurus, and several other genera of 

 reptiles were severally noticed, and reference made to the specimens 

 in the British Museum. The Pelorosaurus was next described 

 somewhat in detail, and the characters of the stupendous humerus, 

 or arm-bone, (4£ feet long), scapula, clavicle, vertebrae, sacrum, and 

 pelvis, were^pointed out, with a view of illustrating a most interest- 



