replaced by ascertained facts. In the latter, he announces that the somewhat bold prediction made by him in the first edition, in 1841, that the ichthyolites of the Old Red Sandstone would be found at least equal to those of all the geological formations united, at the death of Cuvier, was already more than fulfilled. Cuvier enumerated ninety-two species of fossil fishes; Agassiz, in 1846, enumerated one hundred and five in the Old Red Sandstone alone, a formation which had been regarded as poorer in organisms than any other. In this edition was given the list of species, as determined and arranged by Professor Agassiz. Many additions in the shape of notes were also made.
In the first two editions it was stated that there was a gradual increase of size observable in the progress of ichthyolic life, and that the Old Red System exhibited, in its successive formations, this gradation of bulk, beginning with an age of dwarfs, and ending with an age of giants. Since then, it has been ascertained that there were giants among the dwarfs. The remains of one of the largest fish found any where, has been discovered in its lowest formation; whereby he was convinced that the theory of a gradual progression in size, from the earlier to the later Palæozoic formations, though based originally on no inconsiderable amount of negative evidence, must be permitted to drop. On this fact he has based his incontrovertible argument against the "development theory" in his more recent work, already given to the American Public, "Foot-Prints of the Creator."