British floras,--that which occurs in the south-west of Ireland, and corresponds with the flora of the northwest of Spain and the Pyrenees,--had been introduced into the country as early, perhaps, as the times of the Miocene. Be this, however, as it may, there can rest no doubt on the great antiquity of the prevailing trees of our indigenous forests. The oak, the birch, the hazel, the Scotch fir, all lived, I repeat, in what is now Britain, ere the last great depression of the land. The gigantic northern elephant and rhinoceros, extinct for untold ages, forced their way through their tangled branches; and the British tiger and hyæna harbored in their thickets. Cuvier framed an argument for the fixity of species on the fact that the birds and beasts embalmed in the catacombs were identical in every respect with the animals of the same kinds that live now. But what, it has been asked, was a brief period of three thousand years, compared with the geologic ages? or how could any such argument be founded on a basis so little extended? It is, however, to no such narrow basis we can refer in the case of these woods. All human history is comprised in the nearer corner of the immense period which they measure out; and yet, from their first appearance in creation till now they have not altered a single fibre. And such, on this point, is the invariable testimony of Palæontologic science,--testimony so invariable, that no great Palæontologist was ever yet an asserter of the development hypothesis. With the existing trees of our indigenous woods it is probable that in even these early times a considerable portion of the herbs of our recent flora would have been associated, though their remains, less fitted for preservation, have failed to leave distinct trace behind them. We at least know generally, that with each succeeding period there appeared a more extensively useful and various vegetation than that which had gone before. I have already referred to the sombre, unproductive character of the earliest terrestrial flora with which we are acquainted. It was a flora unfitted, apparently, for the support of either graminivorous bird or herbivorous quadruped. The singularly profuse vegetation of the Coal Measures was, with all its wild luxuriance, of a resembling cast. So far as appears, neither flock nor herd could have lived on its greenest and richest plains; nor does even the flora of the Oolite seem to have been in the least suited for the purposes of the shepherd or herdsman. Not until we enter on the Tertiary periods do we find floras amid which man might have profitably labored as a dresser of gardens, a tiller of fields, or a keeper of flocks and herds. Nay, there are whole orders and families of plants of the very first importance to man which do not appear until late in even the Tertiary ages. Some degree of doubt must always attach to merely negative evidence; but Agassiz, a geologist whose statements must be