In many respects the plants and animals of the coal differ much from forms now living. It is probable that the greater part of them are even of different groups or families from the existing ones. But the ferns at least show strong traces of affinity. Here and there we meet with the young fern-leaves coiled up as they now lie on the heather, ready to unfold on the return of spring. We all know these “Bishops' crooks” that nestle in the bottom of the fern-baskets; and when I saw a grand specimen in Mrs. Stackhouse Acton's cabinet (it now graces our museum in Jermyn Street), with the delicate coil of pinnæ, every leaflet in its place, I almost leaped for joy. It was from the Le Botwood coal-field. There is one figured in this work, vol. iii, p. 460 (but the finder has not yet been told, I think, what his fossil is): it is from South Wales, and a beautiful specimen.

Our space was too crowded last month to give the necessary figures of the ferns; and it is but limited now. The leaves or fronds of the delicate Sphenopteris, mentioned p. 101, are very abundant. There are a number of species. S. elegans, S. crassa, and especially S. affinis occur in the lower coals, beneath the mountain limestone of Scotland;—S. artemisiœfolia, S. Honinghausi, S. linearis, S. trifoliata, are all characteristic of our upper coals, and the two last are found in France and Germany.

I said that “all the years invent;

Each month is various to present

The world with some development.”—Tennyson.

Although most of my readers will be perfectly acquainted with the theory proposed by Mr. Darwin to account for the various forms of life that we see on the globe, yet, for the sake of clearness, I will briefly enunciate it.

Mr. Darwin first shows that individuals of the same species vary one with another.

He then shows that, owing to the rapid increase of animal and vegetable life, by which many more are born each year than can possibly survive, there is a continual warfare going on among them for food and other necessaries. This he calls the “struggle for life.”

He then shows that if any animal or plant should have, by variation, any organ or property so modified as to give it some advantage over its fellows in the struggle for life, it will, as a general rule, live longer and produce more offspring; and these offspring will have a tendency to inherit the organ or property modified in the same manner: but if in one of these offspring the organ should be still further modified, it win give him a like advantage over his brethren, and his offspring again will have a tendency to reproduce the organ in its more modified state; and so on. This he calls “Natural Selection.”