282 FINAL CAUSES : THEIR BEARING 



the gravity of bodies at the earth's surface bisects the condi* 

 tions of texture and matter necessary to existence among the 

 sub-aerial vertebrata, the reptiles of the Secondary periods 

 should have grown up in some of their species and genera 

 to the extreme size. A world of frogs, newts, and lizards 

 would have borne stamped upon it the impress of a tame and 

 miserable mediocrity, that would have harmonized ill with 

 the extent of the earth's capabilities for supporting life on a 

 large scale. There would be no principle of adaptation or 

 rule of proportion maintained between an animal kingdom 

 composed of so contemptible a group of beings, and either 

 the dynamic laws under which matter exists on our planet, 

 or the luxuriant vegetation which it bore during the Second- 

 ary ages. And such was not the character of the group 

 which composed the reptile dynasty. The Iguanodon must 

 have been quite as tall as the elephant, — greatly longer, and, 

 it would seem, at least as bulky. The Megalosaurus must 

 have at least equalled the rhinoceros ; the Hylseosaurus 

 would have outweighed the hippopotamus. And when rep- 

 tiles that rivalled in size our hugest mammals inhabited the 

 land, other reptiles, — Ichthyosaurs, Plesiosaurs, and Cetio- 

 saurs, — scarce less bulky than the cetacea themselves, pos- 

 sessed the sea. Not only was the platform of being occupied 

 in all its breadth, but also in all its height ; and it is accord- 

 ing to our simpler and more obvious ideas of adaptation, — 

 simple and obvious because gleaned from the very surface of 

 the universe of life, — that such should have been the case. 

 But it does appear strange, because, und^ the regulation, it 

 would seem, of a principle of adaptation more occult, and, if 

 I may so speak, more Providential, that no sooner are the 

 huge mammals introduced as a group, than, with but a few 

 exceptions, the reptiles appear in greatly diminished propor- 

 tions. They no longer occupy the platform to its full extent 

 of height. Even in tropical countries, in which certain fami 



