2 FOSSIL REPTILIA OF THE 



so that it is with much confidence that the present contribution towards a complete 

 reconstruction of the Iguanodon is now submitted to palaeontologists. 



The discovery and acquisition of the unique specimen, figured in T. I, II, and III, 

 are due to S. H. Beckles, Esq., F.G.S., the author of the papers on the ' Ornithoidich- 

 nites of the Wealden,'* and who first definitely called the attention of geologists to the 

 singular " trifid," or tridactyle impressions in the Wealden of Sussex, of which he was 

 the chief discoverer, and has been the most persevering investigator. 



It seems a peculiarly appropriate reward for these researches, that the acquisition 

 of the fossils demonstrating the tridactyle structure of one of the feet of the Iguanodon 

 should have been reserved for Mr. Beckles. These fossils, moreover, were not fortuitously 

 acquired, but were the fruit of special researches, assiduously carried on by Mr. 

 Beckles on the south-west coast of the Isle of Wight, with a view to materials for 

 completing our knowledge of the great Wealden reptiles. 



Between Brook and Brixton, in the submerged Wealden bed, near low-water mark, 

 indications of the entire skeleton of a young, perhaps half-grown, Iguanodon were 

 detected. The bones of the foot which were most within reach had been very little 

 disturbed. The metatarsus (T. II, fig. 2) was extracted in one piece ; the phalanges 

 of an outer toe (T. I, l iv— 5 iv) were extracted in a second piece : they had been some- 

 what distorted at the time of imbedding, for the matrix had hardened around, and 

 preserved them in that state. The phalanges of the toe of the opposite side of the 

 foot (ib., 1 II— 3 ii) were extracted similarly cemented together by the matrix, but in 

 their natural juxtaposition. Three of the phalanges of the middle toe (ib., l m— 3 m) 

 were also joined together by the matrix ; the fourth, or ungual phalanx of this toe, 

 was extracted separately ; but Mr. Beckles's attention having been, unluckily, diverted 

 to another subject at this time, the fossil got into the hands of an idle looker-on, who 

 cast it into the sea. All the other bones of the foot Mr. Beckles caused to be carefully 

 packed, and transmitted to me for description. 



I employed a skilful lapidary to clear away the adherent matrix, and to separate 

 the cemented phalanges of the distorted toe, for the examination of their articular 

 surfaces, and the resultof my comparisons were communicated briefly to the Geological 

 Society of London, on the occasion of exhibiting the specimen at the meeting held 

 June 17th, 1857. 



As has already been stated, the bones, whether carpal or tarsal, which unite the 

 foot proper to the limb, are wanting. The metapodium,! fortunately, yields the 

 required proof of the precise number of toes. 



* 'Quarterly Journal of the Geological Society,' January, 1851, and November, 1852. 



t I use this word to signify the same segment in both fore- and hind-limbs : "metacarpus" is the 

 specific term for the segment in the fore limb ; " metatarsus " for that in the hind limb. But, in the 

 gradual reconstruction of the skeleton of a strange reptile, it is requisite to have a term expressive of the 

 more general kind of knowledge at first acquired. Metapodial is equivalent to metacarpal or metatarsal. 



