_Neocomian_ 20 species.[DK] (Lower greensand and Speeton clay, Wealden and Hastings sands, Kootanie and Queen Charlotte groups of Canada.) [DK] Including an estimate of Fontaine's undescribed species. Thus we have a great and sudden inswarming of the higher plants of modern types at the close of the Lower Cretaceous. In relation to this, Saporta, one of the most enthusiastic of evolutionists, is struck by this phenomenon of the sudden appearance of so many forms, and some of them the most highly differentiated of dicotyledonous plants. The early stages of their evolution may, he thinks, have been obscure and as yet unobserved, or they may have taken place in some separate region, or mother country as yet undiscovered, or they may have been produced by a rapid and unusual multiplication of flower-haunting insects! Or it is even conceivable that the apparently sudden elevation of plants may have been due to causes still unknown. This last seems, indeed, the only certain inference in the case, since, as Saporta proceeds to say in conclusion: "Whatever hypothesis one may prefer, the fact of the rapid multiplication of dicotyledons, and of their simultaneous appearance in a great number of places in the northern hemisphere at the beginning of the Cenomanian epoch, cannot be disputed."[DL] [DL] "Monde des Plantes," p. 197. The leaves described by Heer, from the Middle Cretaceous of Greenland, are those of a poplar (_P. primæva_). Those which I have described from a corresponding horizon in the Rocky Mountains are a _Sterculites_ (_S. vetustula_), probably allied to the mallows, and an elongated leaf, _Laurophyllum_ (_L. crassinerve_) (Fig. 69), which may, however, have belonged to a willow rather than a laurel. These are certainly older than the Dakota group of the United States and the corresponding formations in Canada. On the eastern side of the American continent, in Virginia, the Potomac series is supposed to be of Lower Cretaceous age, and here Fontaine, as already stated, has found an abundant flora of cycads, conifers, and ferns, with a few angiospermous leaves, which have not yet been described. [Illustration: Fig. 69.--_Stercalia_ and _Laurophyllum_ or Salix, the oldest Angiosperms Known in the Cretaceous of Canada.] In the Canadian Rocky Mountains, a few hundreds of feet above the beds holding the beforementioned species, are the shales of the Mill Creek series, rich in many species of dicotyledonous leaves, and corresponding in age with the Dakota group, whose fossils have been so well described, first by Heer and Capellini, and afterward by Lesquereux. We may take this Dakota group and the quader-sand stone of Germany as types of the plant-bearing Cenomanian, and may notice the forms occurring in them.