Origin of Species Variorum

genus, by differences not greater than we see between the varieties of the same species at the present day; and these parent-species, now generally extinct, have in their turn been similarly connected with more ancient species; and so on backwards, always converging to the common ancestor of each great class. So that the number of intermediate and transitional links, between all living and extinct species, must have been inconceivably great. But assuredly, if this theory be true, such have lived upon the earth.

On the Lapse of Time, as inferred from the rate of Deposition and extent of Denudation .

Independently of our not finding fossil remains of such infinitely numerous connecting links, it may be objected, that time cannot have sufficed for so great an amount of organic change, all changes having been effected very slowly. .. .. .. It is hardly possible for me even to recall to the reader, who is not .. a practical geologist, the facts leading the mind feebly to comprehend the lapse of time. He who can read Sir Charles Lyell's grand work on the Principles of Geology, which the future historian will recognise as having produced a revolution in natural science, yet does not admit how .. vast have been the past periods of time, may at once close this volume. Not that it suffices to study the Principles of Geology, or to read special treatises by different observers on separate formations, and to mark how each author attempts to give an inadequate idea of the duration of each formation or even of each stratum. We can best gain some idea of past time by knowing the agencies at work, and learning how much of the surface of the land has been denuded, and how much sediment has been deposited. As Lyell has well