OF TILGATE FOREST. 
313 
longest diameter 3-2 inches; its sliortest 2*1 inches. 
In this fossil we have another most interesting 
analogy between the Iguanoclon and the Iguana. 
Having thus shown, or rather rendered highly 
probable, that the reptile whose teeth have furnished 
the characters on which the genus Iguanodon is 
founded, ])ossessed also a skeleton, which, except in 
its gigantic proportions, bore a general resemblance 
to that of the recent Iguana, it will be interesting 
to take a summary view of what has been ad\ anced, 
and consider wliat })arts of its osseous fabric we liave 
collected together, and what data they afford from 
which to determine the size, and form, and habits 
of the original. The teeth occur in so perfect a 
state, and in all the variety of form ])roduced by 
the different periods of growth, and the resi)ective 
situations which they occupied in the jaws, as to 
furnish conclusive evidence that the animal not 
only was herbivorous like the Iguana, but that, 
unlike all other known reptiles, it was capable of 
performing mastication like the herbivorous mam- 
malia. The os tympani affords us some inform- 
ation respecting the auditory organs ; and the horn 
exhibits another striking resemblance to the recent 
genus. The vertebral column approaches in some 
respects to that of the fossil crocodiles, unless we 
select the large concavo-convex vertebrm of the 
true lacertian type : the question, however, as to 
which of these svstems should be referred to the 
Iguanodon, cannot, I think, in the present state of 
our knowledge, be positively determined. The 
ribs are too imperfect to furnish any certain data ; 
