Proceedings, 105 



this feature is not entirely confined to the order — it oc- 

 curs in the CrocodUe, for instance. Its occurring in 

 such an unwieldy animal as the Iguanodon is worthy of 

 notice, for although in the birds we can understand its 

 object, — that of rendering the heavier parts of the body less 

 dense, for greater ease in flying, — we can hardly divine what 

 use it could have been to this enormous reptile, whose 

 organisation in other respects by no means fitted it for 

 flight ; and this therefore shows that it was not a modification 

 made to suit certain habits which it happened to follow in 

 common with the birds. In other respects its skeleton dis- 

 played many avian characters, but these, with one exception, I 

 will not enter into now. The exception is this — I dare say you 

 have often noticed the position of a Lizard's legs, sprawled 

 out sideways. The Crocodile, I believe, stands in much the 

 same way, and runs with its feet pointing outwards. Now 

 the Iguanadon possesses an arrangement of the femur or 

 thigh-bone in common with the other Deinosaurs, which 

 enabled it to move its hind legs in the same manner as a 

 bird, with the feet directed forwards, the legs moving in the 

 same plane as the body. There is little doubt, too, from the 

 great difference in size between the comparatively feeble fore 

 and the large and massive hind limbs, that this immense 

 reptile not merely raised itself occasionally on its hind legs, but 

 often walked entirely on them alone, towering up among the 

 Palm trees and feeding on their juicy tops. As it had but three 

 toes on the hind foot, it may be imagined that in this upright 

 attitude the footj)rints which it made in the soft mud of its 

 haunts bore a great resemblance to those of some of our birds 

 in which the hind toe is wanting, and such footprints have 

 been noticed in the Hastings beds of the Wealden formation. 

 I ought here to mention that, in strata belonging to the 

 Trias, which were deposited a very long time before the 

 Wealden beds, three-toed footprints have been long known. 

 At first they were attributed to birds, but as no bird-bones 

 have been found in the Trias, but many Deinosaurian bones, 

 it is a moot point whether they are not the tracks left by 

 these reptiles when walking about on their hind legs. 



