The vegetable kingdom of this period forms an introduction to the vegetation of the present time. Placed at the close of the Secondary epoch, this vegetation prepares us for transition, as it were, to the vegetation of the Tertiary epoch, which, as we shall see, has a great affinity with that of our own times.
The landscapes of the ancient world have hitherto shown us some species of plants of forms strange and little known, which are now extinct. But during the period whose history we are tracing, the vegetable kingdom begins to fashion itself in a less mysterious manner; Palms appear, and among the regular species we recognise some which differ little from those of the tropics of our days. The dicotyledons increase slightly in number amid Ferns and Cycads, which have lost much of their importance in numbers and size; we observe an obvious increase in the dicotyledons of our own temperate climate, such as the alder, the wych-elm, the maple, and the walnut, &c.
“As we retire from the times of the primitive creation,” says Lecoq, “and slowly approach those of our own epoch, the sediments seem to withdraw themselves from the polar regions and restrict themselves to the temperate or equatorial zones. The great beds of sand and limestone, which constitute the Cretaceous formation, announce a state of things very different from that of the preceding ages. The seasons are no longer marked by indications of central heat; zones of latitude already show signs of their existence.
“Hitherto two classes of vegetation predominated: the cellular Cryptogams at first, the dicotyledonous Gymnosperms afterwards; and in the epoch which we have reached—the transition epoch of vegetation—the two classes which have reigned heretofore become enfeebled, and a third, the dicotyledonous Angiosperms, timidly take possession of the earth—they consist at first of a small number of species, and occupy only a small part of the soil, of which they afterwards take their full share; and in the succeeding periods, as in our own times, we shall see that their reign is firmly established; during the Cretaceous period, in short, we witness the appearance of the first dicotyledonous Angiosperms. Some arborescent Ferns still maintain their position, and the elegant Protopteris Singeri, Preissl., and P. Buvigneri, Brongn., still unfold their light fronds to the winds of this period. Some Pecopteri, differing from the Wealden species, live along with them. Some Zamites, Cycads, and Zamiostrobi announce that in the Cretaceous period the temperature was still high. New Palms show themselves, and, among others, Flabellaria chamæropifolia is especially remarkable for the majestic crown at its summit.
“The Conifers have endured better than the Cycadeæ; they formed then, as now, great forests, where Damarites, Cunninghamias, Araucarias, Eleoxylons, Abietites, and Pinites remind us of numerous forms still existing, but dispersed all over the earth.
“From this epoch date the Comptonias, attributed to the Myricaceæ; Almites Friesii, Nils., which we consider as one of the Betulaceæ; Carpinites arenaceus, Gœp., which is one of the Cupuliferæ; the Salicites, which are represented to us by the arborescent willows; the Acerinæ would have their Acerites cretaceæ, Nils., and the Juglanditæ, the Juglandites elegans, Gœp. But the most interesting botanical event of this period is the appearance of the Credneria, with its triple-veined leaves, of which no less than eight species have been found and described, but whose place in the systems of classification still remains uncertain. The Crednerias, like the Salicites, were certainly trees, as were most of the species of this remote epoch.”
In the following illustration are represented two of the Palms belonging to the Cretaceous period, restored from the imprints and fragments of the fossil remains left by the trunk and branches in the rocks of the period ([Fig. 130].)
