turies, they learned to crawl out of the sea and by degrees adapt 
themselves to a life on terra firma. Here perhaps began the 
ferns, horsetails, club-mosses, seed-bearing cycad-like ferns, and 
the earliest relatives of the conifers. Speculation runs rife in this 
mysterious region, this nebula of the land-plant world. Some 
authorities believe our great land plant flora developed from types 
similar to our fresh-water scums and slimes through the liver- 
worts; others equally authoritative suggest they arose as sparsely 
small-leaved tide-water plants from the numerous plant forms of 
the ancient seas. Be that as it may, one fact stands out clearly, 
i. fc\, the presence of the two (or three?) great woody plant groups 
at the beginning of the coal period, and the absence of annual 
rings in their stems, denotes a land of perpetual summer, un- 
marred by seasonal changes. These two or three great groups 
are separated by very distinctive characters, such as the size of 
their leaves, the position of their fruiting bodies, and the nature 
of their internal anatomy. 
As one traces these groups through the luxuriant but damp and 
gloomy forests of the coal period, one finds many strange trees. 
Giant club-mosses (Lepidodendrids, Sigillarians) with trunks 50 to 
100 feet high, clothed with long, spiny leaves or diamond-shaped 
leaf scars, compete with both low-growing and tree-like types of 
ferns, each exceedingly abundant. Tree-like horsetails (Catamites) 
filled the swamps and their somewhat distant relatives, the 
Sphenophyllales, with curious foliage and slender, twining stems, 
were common. The cycad-like ferns, with “near-seeds”, disputed 
the low grounds with the calamites, while the ancestors of the 
conifers ( Cordaiiales ) with long slender trunks surmounted by 
densely branched crowns with large leaves, occupied the higher 
ground. These magnificent though strange and gloomy forests 
of the coal age were not confined to America, but characterized 
the flora of the whole world, east, west, north and south, indicat- 
ing a climate much the same from Arctic to Antarctic. These 
queer forests from man’s standpoint were very uninviting, as 
they lacked those elements which today make them cheery— 
birds, flowers, and butterflies— although some rather objec- 
tionable inhabitants were present, such as cockroaches, frogs, 
scorpions, and centipedes. Huge “snake-feeders,” or dragon 
flies with wings over two feet in spread, flitted hither and thither 
over the calamite marshes, while pop-eyed, queer-shaped mem- 
bers of the frog and salamander group made these already dark 
and gloomy swamps more hideous and uncanny with their 
croakings. 
The majority of our coal fields are the carbonized remains of 
these immense "forest and swamp areas, conditions at that time 
being especially favorable for their preservation as coal. All the 
soft "and cannel coals when properly treated, cut into thin sec- 
tions and subjected to microscopic examination, show wood struc- 
ture, or, in the case of cannel coal, myriads of crushed pollen 
grains and spores with other swamp debris. 
At the close of the more or less tranquil coal period, the earth 
again became restless. Vast changes occurred. Mountain ranges 
arose (among them our own eastern mountains). Enormous 
areas in the southern hemisphere, and to a lesser extent in the 
northern, were overrun by seas of ice. Europe and western 
North America, in part, dried up into deserts. 
Plant life, very naturally, was much affected by these various 
changes. The giant club-moss forests were doomed, and dis- 
appeared, only remnants existing in out-of-the-way places until the 
end of the Paleozoic era. The swamp-loving calamites were more 
fortunate, their extinction not taking place until the coming of 
