Mantellian Museum at Lewes, iS 



effected is clearly that of mastication. * The recent iguanas 

 alone have teeth resembling those of the Iguanodon, particu- 

 larly in the angular form of the crown, and the serrated edges, 

 as may be seen at d, which represents one of these teeth 

 greatly magnified. The metacarpal bones, or those of the 

 feet and toes of the Iguanodon, are of enormous size, one of 

 the tarsal bones measuring 1 3 in. in circumference ; the un- 

 guial bone is also in the museum, only one claw has hitherto 

 been discovered. It appears, also, that this remarkable animal 

 had a horn (^), which nearly resembles in size and form that 

 of the rhinoceros ; it has a bony structure, but it was not 

 united to the skull like the horns of Mammalia. It is to Mr. 

 Pentland, an eminent naturalist who has studied several years 

 under Cuvier, that we are indebted for information respecting 

 the nature of this extraordinary fossil ; when a cast of it was 

 first shown to him, he suggested that it belonged to a saurian 

 animal. A species of living iguana, a native of St. Domingo, 

 has between the eyes an osseous conical horn or process, 

 covered by a single scale; hence this animal is called the 

 Horned Iguana, or Iguana cornuta. This fact, Mr. Mantell 

 observes, establishes another remarkable analogy between the 

 Iguanodon and the animal from which its name is derived. 

 " We have seen," says Mr. Mantell, " that the teeth are at 

 least twenty times larger than those of the iguana of 3 or 

 4 ft. in length, that the thigh bone is of equally enormous 

 proportions, and were we to calculate the probable magnitude 

 of the original, from the data which the metatarsal bone 

 affords, we might well exclaim, that the realities of geology 

 exceed the fictions of romance." 



There is the highest probability, from the resemblance of 

 the teeth and large bones found in Tilgate Forest to those of 

 the iguana, that both the teeth and bones belonged to one 

 species of unknown animal ; but, as no portion of the jaw has 

 hitherto been found, we have not at present obtained an abso- 

 lute certainty respecting this fact. Cuvier, in the last edition 

 of his Regne Animal recently published, says that the cha- 

 racter of the Geosaurus f of Soemmering, the Megalosaurus of 

 Buckland, and the Iguanodon of Mantell, are not yet so com- 

 pletely ascertained as to enable us to class them with certainty. 

 Should it be eventually proved that the large bones and the 

 teeth, found in Tilgate Forest, belonged to different animals, 



* Mr. Mantell conjectures that the food of the Iguanodon consisted 

 chiefly of plants furnished with rough thick stems, as indicated by these 

 remains ; hence a peculiar structure of the tooth was required. 



f Geo saurusy earth lizard. Megalo saurus, great lizard. 



