18 
" certainly very wonderful was the development which it 
" then did receive ; reptiles became everywhere the lords and 
" masters of this lower world, taking possession of all the 
" three old terrestrial elements, earth, air, and water, 
" enaliosauri, plesiosauri, pterodactyli ; the lakes and rivers 
" abounded in crocodiles and fresh water tortoises of ancient 
" type and fashion ; and its woods and plains were the 
" haunts of a strange reptilian fauna, of what has been 
" termed ' fearfully great lizards/ some of which, as the 
" iguanodon, rivalled the largest elephant in height, and 
" greatly more than rivalled him in length and bulk. It 
" seems not improbable that the reptiles of the oolitic period 
r< consisted of as many genera and species as the class mam- 
" malia of the present time." 
I would merely add that the abundance of reptile life 
displayed at this period, and through the whole of the oolite 
period, affords full proof of the existence of a tropical climate 
throughout the whole epoch, since these cold-blooded animals 
have little power of generating heat in their own bodies. 
Hence the magnitude, variety, and activity of reptile life now 
under the tropics — hence the smallness, feebleness, summer 
life, and winter sleep of the very few species in our northern 
regions, — and hence the earth's nearer proximity to the sun. 
Ascending from the new red sandstone, through the oolite up 
to the chalk, there is the same evidence of the gradually 
decreasing temperature of the earth's climate, and also a 
gradually expanding crust of the earth. The difference of 
quantity between the few oolitic plants and the vast heaps of 
vegetable reliquiae in the older coal strata, is one great proof 
and very important. "During the oolitic period/' says 
Phillips, "the arctic land was covered by plants like those of 
" hot regions, whose vegetable ruins have locally generated 
"coal beds, adorned by coleopterous, neuropterous insects, 
" among which the flying lizard (pterodactylus) spread his 
