﻿IS 



FOSSIL REPTILIA OF THE WEALDEN FORMATIONS. 



description might have been taken from the type example of the sacrum of Iguanodon 

 Mantctti, figured in the Pal. Society vol. for 1855, above cited; and it adds to the satis- 

 faction I feel in the additional knowledge of the osseous structure of the great herbivorous 

 Dinosaur, which we may inferentially derive from the additional or better preserved parts 

 of the smaller species; but which light it is sought to obscure by the Ilgpsilophodon 

 curtain. 



I have a strong belief and expectation that when specimens of the palatal structure of 

 Iguanodon Mantelli are obtained they will resemble those of Iguanodon Foxii, figured in 

 my PI. II of the present Monograph, 'proved' and marked for 'Press' in June, 1873. 

 The ' stout body ' of the pterygoid is there shown in fig. 5 {at 24) ; the posterior process 

 (*) joining the large ' pterapophysis ' or basisphenoidal fork (<) ; the root of the branch («), 

 which Mr. Hulke 1 terms the ' quadratic process ' = my ' tympanic process,' and the 

 extension of the outer concave border to join the ' ectopterygoid 5 (c) ; also the separation, 

 medially, of both pterygoid and palatines. Such, I repeat, may be expected to be, in the 

 main, the palatal character of the great herbivorous Dinosaur. That expectation is further 

 and strongly supported by the significant correspondence between Iguanodon Mantelli 

 and Iguanodon Foxii in the characteristic and peculiar relations of the teeth to the jaws. 

 " As in Iguanodon Mantelli the outer wall of the tooth-groove sends inwards partitions, 

 which practically separate the teeth from one another, and must have afforded them a 

 very firm support ; but I doubt if these partitions actually reached the inner wall and 

 became confluent with it." 2 I have no doubt, from the shape and length of the root or 

 fang of the lanidriform tooth (PI. II, figs. 19, 20, of the present ' Monograph') that it was 

 " contained in a distinct separate socket." The difference, therefore, in the mode of 

 implantation of teeth in the same jaw, as in the shape of vertebrae in the same sacrum, 

 and in the shape of unequal phalanges in the fore and hind feet, are characters common 

 to both Iguanodon Mantelli and Iguanodon Foxii. 



• R. 0. 



December 4<t/i, 1873. 



' Abstracts of Proceedings,' p. 1. 



2 'Quart. Journ.' (June, 1873), p. o25. 



