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.

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 slowly.

It is hardly possible for me to recall to the reader who is not a practical geologist, the facts leading the mind feebly to comprehend the lapse of time.