more fortunate, their extinction not taking place until the coming 
of the next era, where they gave place to the true horsetails, a 
much more lowly type, but perhaps better fitted to cope with the 
changing conditions of the long stretch of time between then and 
now. Ferns weremore abundant than ever, running riot in variety 
of form and adaptability. The same was true of their near rela- 
tives, the curious cycad-like ferns which bore seed-like struc- 
tures. Moreover, representatives of true cycads (sago palms) 
appeared. The forests of Cordaites gave place to still higher 
types of conifers, some of which had foliage similar to our 
present-day yews. Others were probably ancestors of the temple 
conifer, ( Ginkgo ) the curious maiden-hair tree, which escaped 
extinction from our present flora, only because it found favor in 
the eyes of an oriental priesthood. 
The closing of the Paleozoic era marked the doom of the club- 
mosses, selaginellaS, horsetails and their relatives as a dominat- 
ing element of the earth’s flora. In the coal period they had 
reached their millenium, both in grandeur and variety of form 
and in number of individuals. Henceforth to the present time, 
their history has been one of increasing insignificance. To-day 
they are represented by a few very modest, inconspicuous types 
such as the ground pines of our northern forests, the selaginellas 
or little club-mosses so common as ground carpets in tropical 
forests at certain elevations, and the scouring rushes (horsetails), 
inhabitants especially of low swampy regions and of railroad 
embankments. This latter group in some forms still reaches a 
fair height, 15-20 feet, and in a few regions they are still locally 
a large element of the vegetation,— relics of the past, much as are 
the redwoods of the Pacific coast, a group of plants once common 
over the whole world from Greenland to Australia. 
Contrasted with the tranquil Paleozoic, the next era, the Meso- 
zoic, is an age of marvellous activity and change, with a climate 
for the most part mild and seasonless. Climatic zones slowly put 
in their appearance as the age progressed toward its close. These 
zonal differences in temperature were probably slight at first, and 
more noticeable on the sea, the Arctic waters being cooler. 
Mountain-making took place on a grand scale and volcano activ- 
ity, especially near the close of the era, must have presented 
scenes rivalling those once claimed for Gehenna, the old-time 
Hades. The result of all this turmoil and change lies before us 
to-day as the Cascades, Sierra Nevadas and the Rockies. 
Animal life also seemed to be outdoing itself, especially in an 
effort toward grotesqueness in form and gigantic proportions. 
Reptiles of innumerable shapes and sizes walked and crawled 
over the land, swam the seas and filled the air with their whir- 
ring wings, some of which had a spread of twenty feet. Seas and 
rivers swarmed with crocodiles and huge turtles. Winged dragons 
with bird-like heads and teeth-filled jaws were no superstition in 
those days, nor were the mountains of flesh and bone, 50-70 feet 
long, which took the form of plant and animal-eating dinosaurs, 
— animals, with the exception of whales, the largest the world 
has ever known. Birds were uncommon almost to the end of the 
era, while mammals (animals which suckle their young, such as 
are most of our present-day land animals) were small, few and 
insignificant. 
The plants of such a world were no less marvellou s, especial!}' 
toward the latter half of the era, when representatives of our 
modern flowering plants appeared. In the first part of the era, 
ferns became less abundant and resembled many of our tropical 
forms of to day. The club-mosses were much simpler and largely 
stragglers, while true horsetails, in canebrake-like thickets, occu- 
pied the margins of the swamps and inland lakes and seas, in place 
4 
