ROOM III. HORN OF THE IGUANODON. 299 



tiuctly impressed by the vessels of the integument by which 

 it was originally covered. 



There is no evidence to prove that this bone belonged to 

 the Iguanodon, but that it is a dermal tubercle there cannot 

 be any reasonable doubt; and as it closely resembles the 

 frontal horn of the Iguana cornuta, it is highly probable 

 it was such an appendage: or it may have been one of a 

 series extending down the back. In the present state of our 

 knowledge, we are warranted in retaining the name sanctioned 

 by the illustrious Cuvier. 1 



Dimensions of the Hinder Limbs of the Iguanodon. Al- 

 though the prodigious size of the hind limbs of the herbi- 

 vorous reptile of the Wealden is sufficiently apparent from 

 the single bones deposited in the British Museum, and de- 

 scribed in the preceding pages, yet with the view of convey- 

 ing to the reader a just idea of the stupendous proportions 

 of this part of the skeleton of the Iguanodon, I will offer a few 

 remarks on some enormous bones, which have been collected 

 from the Wealden deposits of Tilgate Forest and the Isle of 

 Wight, in the course of the last few years, and which are either 

 in my own possession, or in the collections of my friends. 



" In the course of last autumn I procured from the cliffs 

 near Brook Point, a locality well known to the British geo- 

 logist from the fossil forest exposed at its base, 2 portions of 

 two corresponding femora, tibiae, and several vertebrae, frag- 

 ments of ribs, &c. of Iguanodons. The most entire bone is 

 the left femur ; it consists of the shaft from above the popli- 

 teal space to the root of the outer trochanter : the head and 

 condyles are both wanting; the inner trochanter remains: 

 the length of this fossil is 3 feet; circumference of the shaft 



1 After the lapse of eighteen years, the Hunterian Professor, it would 

 seem, has discovered that this "horn" is an ungual bone: for, alluding 

 to a bone of the Mosasaurus, Professor Owen remarks : " The phalanx 

 in question much resembles that in the British Museum (No. 384 Man- 

 tellian Collect.), which has bee^i described as the ' Horn of the Iguano- 

 don.'" ("Fossil Keptilia of the Cretaceous Formations," 1851, p. 36.) 

 I have again carefully examined three of these bones, and may remark, 

 that in addition to the reasons assigned in the text, the absence of 

 lateral furrows in the dermal horns or spines, and the constant presence 

 of such vascular grooves in every reptilian ungual phalanx hitherto found 

 in the Wealden, and the form of the base, substantiate my opinion. 



2 " See my Geological Excursions round the Isle of Wight,' p. 277." 



