96 EXTINCT MONSTERS. 
their command, it is wonderful that their forecasts should have 
turned out so successful. Thus Professor Owen predicted for 
the Iguanodon a total length of twenty-eight feet, and specimens 
discovered of late years show a length of twenty-four feet. In 
some, the thigh-bone exceeded a yard in length; this indicated 
an animal of great size, since in the largest crocodiles this bone 
is scarcely a foot long. Again, Dr. Mantell, from a study of the 
imperfect jaw-bones in his collection, concluded that the lower 
jaw was invested with a well-developed fleshy flexible lip, and 
that the mouth was provided with a tongue of great mobility and 
power. “There are strong reasons,” he says, ‘for supposing 
that the lip was flexible, and, in conjunction with the long fleshy 
prehensile tongue, constituted the instrument for seizing and 
cropping the leaves and branches, which, from the construction 
of the molars, we may infer, constituted the chief food of the 
Iguanodon. The mechanism of the maxillary organs (jaws), as 
elucidated by recent discoveries, is thus in perfect harmony with 
the remarkable characters which rendered the first known teeth 
so enigmatical ; and in the Wealden herbivorous reptile we have 
a solution of the problem, how the integrity of the type of 
organisation peculiar to the class of cold-blooded vertebrata was 
maintained, and yet adapted, by simple modifications, to fulfil 
the conditions required by the economy of a gigantic terrestrial 
reptile, destined to obtain support exclusively from vegetable 
substances; in like manner, as the extinct colossal herbivorous 
Edentata (sloths, see Chapter XII.), which flourished in South 
America ages after the country of the Iguanodon and its in- 
habitants had been swept away from the face of the earth.” 
Dr. Mantell also was the first to prove, from the nature of the 
Wealden strata, that they were deposited in or near the estuary 
of a mighty river. With regard to the aspect of the country in 
which the Iguanodon flourished, he showed that coniferous trees 
probably clothed its Alpine regions; palms and arborescent 
ferns, and cycadaceous plants (2¢. plants resembling the modern 
