THE STORY TOLD BY FOSSIL PLANTS
may be seen; Permian is from the province of Perm, in Russia. Or the name may have been suggested by the character of the rock, as Carboniferous, a term applied to the rocks of the coal age.
After this era of ancient life, the Palaeozoic, came the Mesozoic era, a time in which the forms were intermediate between the old and the new. The Mesozoic era is divided into three periods—the Triassic, the Jurassic, and the Cretaceous. The Triassic is so named because in that period three principal kinds of rock formations were deposited in southern Germany; the Jurassic is so named because the rocks of that period are very conspicuous in the Jura Mountains; and the Cretaceous gets its name from the fact that its characteristic rock is chalk (creta in Latin).
The Mesozoic era was followed by the Cenozoic, the time of modern life. In the rocks of this era we find the remains of warm-blooded animals and flowering plants, and in those of the later part of the era we find the skeletons and flint implements of ancient man.
Many fossil seaweeds are scattered through the older rocks, but the first land plants found in abundance as fossils lived in middle Palaeozoic time (Devonian). (See table on page 160.) Some of these may be considered transitional between seaweeds and true land plants (Fig, 2). Others were synthetic forms combining features of organization which during subsequent ages became segregated and characteristic of separate orders of plants. Such an ancestral plant is Hyenia (Fig. 4) which combines features of the later club mosses and horsetails. Others by their complexity indicate a long period of terrestrial existence. Some of these Devonian plants are true seed ferns (Figs. 3 and 4); others are arborescent club mosses, which combine the features of plants of later Palaeozoic time (Fig. 5). Another later Devonian type, widespread geo-
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