1852.] OF THE ROYAL INSTITUTION. 145 
trunks, and branches, of coniferous trees, drifted from the country 
of the Iguanodon. 
The facts thus rapidly noticed prove that during the deposition of 
the Wealden, Oolitic, and Cretaceous strata, there existed an 
extensive Island or Continent, diversified by hills and valleys, and 
traversed by streams and rivers teeming with fishes, crustaceans, 
and mollusca, closely allied to types which at present inhabit the 
fresh-water of temperate regions ; and that with these were asso- 
ciated fluviatile turtles, and crocodilian reptiles, whose living 
analogues are restricted to tropical climes. Colossal herbivorous 
and carnivorous saurians, differing essentially in structure from all 
known existing forms, were the principal inhabitants of the dry 
land; and these, together with flying lizards, and possibly a few 
birds, and very small mammalia, constituted the vertebrate fauna 
of the country, or countries, which supplied the materials of the 
Wealden strata, and of the fluvio-marine deposits which are interca- 
lated with the purely oceanic beds of the Oolite and Chalk. 
Thus it appears, according to the present state of our know- 
ledge, that the classes Mammalia and Aves, which constitute the 
essential features of the terrestrial zoology of most countries, were 
represented through a period of incalculable duration solely by 
two genera of very diminutive mammals, and a few birds; while 
the air, the land, and the waters, swarmed with peculiar rep- 
tilian forms, fitted for aerial, terrestrial, and aquatic existence. 
Admitting to the fullest extent the effect of causes that may be 
supposed to have occasioned the absence of mammalian remains in 
the secondary deposits, yet the immense preponderance of the reptile 
tribes is unquestionable. Some authors have attempted to account 
for this anomaly by assuming that antecedently to the Eocene 
period, our planet was not adapted for the existence of mammalia, in 
consequence of its atmosphere being too impure to support higher 
types of animal organization than the cold-blooded vertebrata. But 
the certainty that some forms of marsupial and placental mammalia 
inhabited the countries of the Megalosaurus and Pterodactyle, — that 
birds in all probability existed with the Izuanodon, — and the fact 
that insects and mollusca, and trees and plants, which now inhabit 
regions abounding in birds, and mammualia, flourished during the 
“Age of Reptiles,’— demonstrate that the physical conditions of 
the earth, and the constitution of the atmosphere, and of the 
waters, differed in no essential respect from those which now prevail, 
and that the laws which govern the organic and inorganic king- 
doms of nature have undergone no change. 
That the class Reptilia was developed during the periods em- 
braced in this discourse to an extent far beyond what has since 
taken place appears to be indisputable; nor can any satisfactory 
solution of the problem be offered from the data hitherto obtained. 
Future discoveries may however show that coeval with the country 
of the Iguanodon there were regions tenanted by birds and 
mammalia; and that the almost exclusively reptilian fauna of the 
lands whose zoological and botanical characters have formed the 
