OF TILGATE FOREST. 
305 
bones wliicli are found associated with the teeth, 
and approximate more nearly to the corresponding 
bones of the Iguana than to those of the other 
saurians, belong to the Iguanodon ; and I now 
])i'oceed to describe them : sooner or later, the 
discovery of some portions of the skeleton in con- 
nection with the jaws and teeth will establish or 
refute this conclusion. 
Bones of the Head H frontal hone, lij, inch 
long, very closely corresponding to the os frontis 
of the Iguana, is figured PI. II. fig. b. ; it adheres 
to the sandstone by its dermal aspect, is very 
thick, and differs in some })articidars from that 
of the recent animal ; it must have belonged to a 
very young individual, whose length could not 
have exceeded five feet. 
Ethmoid hone. I have in my collection a muti- 
lated bone, which i\I. Cuvier suggested might 
approximate to an ethmoid bone of a lizard of 
enormous size, certainly larger than that of the 
Geosaurus of Manheim.* 
Os tympani. This bone, which forms part of 
the auditory apparatus, and in reptiles unites the 
lower jaw with the skull, is placed vertically, and 
varies verv much in form in the ditferent saurian 
genera.t Two almost perfect bones of this kind 
have been discovered, which differ in many essen- 
tial particulars from any previously noticed, yet 
approximate in some respects to the os tympani of 
* Vide Memoire suF quclques parties inoiiis connues du Squelette 
des Saiiriens Fossiles de Macstricht, par M. A. Camper, in which the 
ethvidid ot the Cteosaurus is figured. PI. I. fig. 1. 
f Tliis bone is analogous to the os quadratum in birds. 
X 
