Origin of Species Variorum

of the forms of life, and the order would falsely appear to be strictly parallel; nevertheless the species would not be all the same in the apparently corresponding stages in the two regions.

On the Affinities of Extinct Species to each other, and to Living Forms .

Let us now look to the mutual affinities of extinct and living species. They all fall into a few grand classes; and this fact is at once explained on the principle of descent. The more ancient any form is, the more, as a general rule, it differs from living forms. But, as Buckland long ago remarked, all extinct species can be classed either in still existing groups, or between them. That the extinct forms of life help to fill up the .. intervals between existing genera, families, and orders, cannot be disputed. For if we confine our attention either to the living or to the extinct alone, the series is far less perfect than if we combine both into one general system. With respect to the vertebrata, whole pages could be filled with illustrations from Owen, showing how extinct animals fall in between existing groups. Cuvier ranked the Ruminants and Pachyderms, as the two most distinct orders of mammals; but Owen has discovered so many fossil links, that he has had to alter the whole classification, ... and has placed certain pachyderms in the same sub-order with ruminants: for example, he dissolves by fine gradations the apparently wide difference between the pig and the camel. ↑ Another distinguished palæontologist, M. Gaudry, shows that very many of the fossil mammals discovered by him in Attica connect in the plainest manner existing genera. Even the wide interval between birds and reptiles has been shown by Professor