IN FAVOR OF REVEALED RELIGION. 309 
dominant organisms are crustaceans and molluscs. Now, such 
being the ascertained facts of our science, we are, I think, jus- 
tified in still holding against the disciples of the one school to 
which I have referred, that there has been progress in creation 
from a lower to a higher level. So far as there exists any evi- 
dence on the subject at all, we must hold that, in at least the 
group, the Paleozoic existences were of a lower and humbler 
order than those of the Secondary ages, and those of the 
Secondary ages of a lower and humbler order than those of 
the periods of the Tertiary. As shown by the vertebrate 
remains of the geologic epochs, the balance, which greatly 
preponderated in the times of the Tertiary in favor of the 
mammals, greatly preponderated in the times of the Second- 
ary in favor of the reptiles, and in the long evanished Palxo- 
zoic ages, in favor of the fishes. And so now, as before, these 
three great periods may be properly described as the periods 
of the fish, the reptile, and the mammal; nor do the late excep- 
tional cases, in which traces of reptiles have been found among 
the Paleozoic fishes, or of mammals among the Secondary rep- 
tiles, interfere more with the justness of such designations than 
the existence in New Zealand of one small indigenous mam- 
mal of the rat family, among its some fifty or sixty ornithic 
species, interferes with the propriety of designating it a land of 
birds, or the existence among the some forty-six pouched spe- 
cies of Australia of a few mammals that are not pouched, with 
the propriety of designating it a land of marsupials. Let us 
be content, then, as geologists, to found our deductions, until 
our science shall have provided us with a new class of facts, on 
the facts which we already possess. No sooner were we intro- 
duced, through the discovery of his grace the Duke of Argyll, 
to a small Tertiary deposit in the island of Mull, than we found 
that it yielded in abundance leaves of the buckthorn and the 
plane. No sooner had our boulder clays and drift gravels begun 
