In the illustration, I have grouped some of the characteristic Mammalian forms of the Miocene, as we can restore them from their scattered bones, more or less conjecturally; but could we have seen them march before us in all their majesty, like the Edenic animals before Adam, I feel persuaded that our impressions of this wonderful age would have far exceeded anything that we can derive either from words or illustrations. I insist on this the more that the Miocene happens to be very slenderly represented in Britain; and scarcely at all in north-eastern America; and hence has not impressed the imagination of the English race so strongly as its importance justifies. The next succeeding period, that of the Pliocene, continues the conditions of the last, but with signs of decadence. Many of the old gigantic pachyderms have disappeared; and in their stead some familiar modern genera were introduced. The Pliocene was terminated by the cold or glacial period, in which a remarkable lowering of temperature occurred over all the northern hemisphere, accompanied, at least in a portion of the time, by a very general and great subsidence, which laid all the lower parts of our continents under water. This terminated much of the life of the Pliocene, and replaced it with boreal and Arctic forms, some of them, like the great hairy Siberian mammoth and the woolly rhinoceros, fit successors of the gigantic Miocene fauna. How it happened that such creatures were continued during the Post-pliocene cold, we cannot understand till we have the Tertiary vegetation before us. It must suffice now to say, that as the temperature was modified, and the land rose, and the Modern period was inaugurated, these animals passed away, and those of the present time remained. Perhaps the most remarkable fact connected with this change, is that stated by Pictet, that all the modern European mammals are direct descendants of Post-pliocene species; but that in the Post-pliocene they were associated with many other species; and these, often of great dimensions, now extinct. In other words, the time from the Pliocene to the Modern, has been a time of diminution of species, while that from the Eocene to the Miocene was a time of rapid introduction of new species. Thus the Tertiary fauna culminated in the Miocene. Yet, strange though this may appear, Man himself, the latest and noblest of all, would seem to have been a product of the later stages of the time of decadence. I propose, however, to return to the animals immediately preceding man and his contemporaries, after we have noticed the Tertiary flora and the Glacial period. CHAPTER XI. THE NEOZOIC AGES (_continued_).