average proportion to the spinal cord of not more than two to one, comes first,—it is the brain of the fish; that which bears to the spinal cord an average proportion of two-and-a-half to one succeeded it,—it is the brain of the reptile; then came the brain averaging as three to one,—it is that of the bird. Next in succession came the brain that averages as four to one,—it is that of the animal; and last of all there appeared a brain that averages as twenty-three to one,—reasoning, calculating Man had come upon the scene.'[1]
M. Agassiz, in his Essay on Classification, has devoted a chapter to the 'Parallelism between the Geological Succession of Animals and Plants and their present relative Standing;' in which he has expressed a decided opinion that, within the limits of the orders of each great class, there is a coincidence between their relative rank in organisation and the order of succession of their representatives in time.[2]
Professor Owen, in his Palæontology, has advanced similar views, and has remarked, in regard to the vertebrata, that there is much positive as well as negative evidence in support of the doctrine of an advance in the scale of being, from ancient to more modern geological periods. We observe, for example, in the triassic, oolitic, and cretaceous strata, not only an absence of placental mammalia, but the presence of innumerable reptiles, some of large size, terrestrial and aquatic, herbivorous and prædaceous, fitted to perform the functions now discharged by the mammalia.
The late Professor Bronn, of Heidelberg, after passing in review more than 24,000 fossil animals and plants, which he had classified and referred each to their geological position in his 'Index Palæontologicus,' came to the conclusion that, in the course of time, there had been introduced into the
