668 KANSAS CITY REVIEW OF SCIENCE. 
These trees grew to the height of 70 or even roo feet; they probably had 
few large branches that were covered with long, stiff, pointed leaves. The roots, 
of which the soil seems to have been filled, had the peculiarity of terminating 
quite abruptly, as if they had been of the nature of rhizoma. These were proba- 
bly the largest trees that flourished in the Carboniferous age, their remains hav- 
ing been found four to five feet in diameter, and with an estimated height of 95 
to 100 feet. These resembled on one hand palms or cycads, and on the other 
they were closely allied to the lycopods. Indeed, so strong are the affinities of 
this for both of these families, that by some naturalists it is classed with the one, 
and by others it 1s placed with the other. The Sigillarids were among the most 
numerous of all the orders that flourished during this age. More than twenty 
species have been discovered, and extensive beds of coal appear to have been 
formed almost exclusively of plants belonging to this family. The Lepidodendra 
were great trees of the Club Moss type that grew to the height of 40 to 60 feet, 
and with trunks that sometimes attained to three or four feet in diameter. The 
typical genus, Lepidodendron, which was probably one of the largest of the fam- 
ily, had a bark regularly marked in a rkomboidal pattern resembling the scaly sur- 
face ofa ganoid fish, from which the genus takes its name, which signifies ‘‘scale 
tree.’ 
These marks which run obliquely around the stem represent the phylotaxis, 
and give the stem a pleasing and somewhat ornate appearance. The trees were 
furnished with long, spreading roots, that were calculated to fix them firmly in 
the soft, boggy soil in which they probably grew. In general appearance these 
trees resembled the modern Auricaria or Norfolk pine, or a giant club-moss. In 
fructification they resembled the true club-mosses, but the stem possessed 
a true pith, and in this respect the genus was raised far above the 
modern club-mosses and showed decided affinities with endogens. The 
most abundant family of plants of the coal age, in both individuals and 
species, were ferns. The erm family constituted about one-third of all the plants 
of this age in both Europe and America. Im the British coal flora, of less than 
300 species of plants, 120 were ferns and 45 more were more nearly allied 
to ferns than to any other known family. The total number of species of plants 
in the coal measures of America was about 500, not less than 250, or one-half, of 
which are ferns. These ferns varied in size from the humble, creeping species 
that trailed on the ground to those of towering trees. In order to enable them 
to resist the force of the wind the lower part of the trunk was strengthened by 
having the soft, cellular tissue abundantly penetrated by bundles or buttresses of 
dense vascular fiber, as tough and elastic as the strongest wood. The last and 
highest family of vegetation that flourished during the coal measure period, and 
that contributed toward making up that vast accumulation of vegetable remains, 
the carbonization of which produced the various beds of coal of that age, is that of 
Gymnospermous conifers. ‘These did not enter into the composition of coal to a 
very great extent as compared with the previously mentioned families, their 
