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Cretaceous. It will thus be convenient to confine ourselves in this chapter to the flora of the earlier Mesozoic.
Passing over for the present the cryptogamous plants already familiar in older deposits, we may notice the new features of gymnospermous and phænogamous life, as they present themselves in this earlier part of the great reptilian age, and as they extended themselves with remarkable uniformity in this period over all parts of the world. For it is a remarkable fact that, if we place together in our collections fossil plants of this period from Australia, India, China, Siberia, Europe, or even from Greenland, we find wonderfully little difference in their aspect. This uniformity we have already seen prevailed in the Palæozoic flora; and it is perhaps equally marked in that of the Mesozoic. Still we must bear in mind that some of the plants of these periods, as the ferns and pines,
for example, are still world-wide in their distribution; but this does not apply to others, more especially the cycads (Fig. 65). The cycads constitute a singular and exceptional type in the modern world, and are limited at present to the warmer climates, though very generally distributed in these, as they occur in Africa, India,
Japan, Australia, Mexico, Florida, and the West Indies. In the Mesozoic age, however, they were world-wide in their distribution, and are found as far north as Greenland, though most of the species found in the Cretaceous.
of that country are of small size, and may have been of low growth, so that they may have been protected by the snows of winter. The cycads have usually simple or unbranching stems, pinnate leaves borne in a crown at top, and fruits which, though somewhat various in structure and arrangement, are all of the simpler form of gymnospermous type. The stems are exogenous in structure, but with slender wood and thick bark, and barred tissue, or properly as tissue intermediate between this and the disc-bearing fibres of the pines.
Though the cycads have a considerable range of organisation and of fructification, and though some points in reference to the latter might assign them a higher place, on the whole they seem to occupy a lower position than the conifers or the cordaiteæ of the Carboniferous. In the Carboniferous some of the fern-like leaves assigned to the genus Noeggerathia have been shown by Stur and Weiss to have been gymnosperms, probably allied to cycads, of which they may be regarded at least as precursors. Thus the cycadean type does not really constitute an advance in grade of organisation in the Mesozoic, any further than that, in the period now in question, it becomes much more developed in number and variety of forms. But the conifers would seem to have had precedence of it for a long time in the Palæozoic, and it replaces in the Mesozoic the Cordaites, which in many respects excelled it in complexity.
The greater part of the cycads of the Mesozoic age would seem to have had short stems and to have constituted the undergrowth of woods in which conifers attained to greater height. An interesting case of this is the celebrated dirt-bed of the quarries of the Isle of Portland, long ago described by Dean Buckland. In this. fossil soil trunks of pines, which must have attained to great height, are interspersed with the short, thick stems of cycads, of the genus named Cycadoidea by Buckland,
and which from their appearance are called "fossil birds' nests" by the quarrymen. Some, however, must have attained a considerable height so as to resemble palms.
The cycads, with their simple, thick trunks, usually marked with rhombic scars, and bearing broad spreading crowns of large, elegantly formed pinnate leaves, must have formed a prominent part of the vegetation of the northern hemisphere during the whole of the Mesozoic period. A botanist, had there been such a person at the time, would have found this to be the case everywhere from the equator to Spitzbergen, and probably in the southern hemisphere as well, and this throughout all the long periods from the Early Trias to the Middle Cretaceous. In a paper published in the "Linnæan Transactions" for 1868, Dr. Carruthers enumerates twenty species of British Mesozoic cycads, and the number might now be considerably increased.
The pines present some features of interest. We have already seen their connection with the broad-leaved Cordaites, and in the Permian there are some additional
FIG. 66.-Salisburia (Gingko)
types of broad-leaved coniferæ. In the Mesozoic we have great numbers of beautiful trees, with those elegant fan-shaped leaves characteristic of but one living species, the Salisburia, or gingko-tree of China. It is curious that this tree, though now limited to eastern Asia, will grow, though it rarely fruits, in most parts of tem
perate Europe, and in America as far north as Montreal, and that in the Mesozoic period it occupied all these regions, and even Siberia and Greenland, and with many and diversified species (Fig. 66).
Salisburia belongs to the yews, but an equally curious fact applies to the cypresses. The genus Sequoia, limited at present to two species, both Californian, and one of them the so-called "big tree," celebrated for the gigantic size to which it attains, is represented by species found as far back at least as the Lower Cretaceous, and in every part of the northern hemisphere.* It seems to have thriven in all these regions throughout the Mesozoic and early Kainozoic, and then to have disappeared, leaving only a small remnant to represent it in modern days. A number of species have been described from the Mesozoic and Tertiary, all of them closely related to those now existing (Fig. 67).
The following notice of these trees is for the most part translated, with some modifications and abridgment, from a paper read by the late Prof. Heer before the Botanical Section of the Swiss Natural History Society:
FIG. 67.-Sequoia Smithiana, Heer.
The name itself deserves consideration. It is that of an Indian of the Cherokee tribe, Sequo Yah, who invented an alphabet without any aid from the outside world of culture, and taught it to his tribe by writing it upon
*In the Eocene of Australia.
leaves. This came into general use among kees, before the white man had any knowledg afterward, in 1828, a periodical was publis. character by the missionaries. Sequo Yah w from his home in Alabama, with the rest of hi settled in New Mexico, where he died in 1843. When Endlicher was preparing his syno conifers, in 1846, and had established a num genera, Dr. Jacbon Tschudi, then living with brought before his notice this remarkable man, him to dedicate this red-wooded tree to the me literary genius so conspicuous among the re America. Endlicher consented to do so, and deavored to make the name pronounceable by two of its letters.
Endlicher founded the genus on the redwo Americans, Taxodium sempervirens of Lamb; a the species Sequoia sempervirens. These trees f forests in California, which extend along the co as Oregon. Trees are there met with of 300 feet and 20 feet in diameter. The seeds have been to Europe a number of years ago, and we alrea upper Italy and around the Lake of Geneva, and land, high trees; but, on the other hand, they proved successful around Zurich.
In 1852, a second species of Sequoia was disco California, which, under the name of big tree, tained a considerable celebrity. Lindley describ 1853, as Wellingtonia gigantea; and, in the f year, Decaisne and Torrey proved that it belo Sequoia, and that it accordingly should be called. gigantea.
While the Sequoia sempervirens, in spite of structiveness of the American lumbermen, still large forests along the coast, the Sequoia gigantea fined to the isolated clumps which are met with in