The family of the sago-like Cycadeae approaches most nearly to palms in its
external appearance, while these plants are specially allied to Coniferae in
respect to the structure of their blossoms and seed.*
[footnote] *Kunth, 'Anordnung der Pflanzenfamilien', in his 'Handb. der
Botanik', s. 307 und 314.
Where many beds of coal are superposed over one another, the families and
species are not always blended, being most frequently grouped together in
separate genera; Lycopodiaceae and certain ferns being alone found in one
bed, and Stigmariae and Sigillariae in another. In order to give some idea
of the luxuriance of the vegetation of the primitive world, and of the
immense masses of vegetable matter which was doubtlessly accumulated in
currents and converted in a moist condition into coal,* I would instance the
Saarbrucker coal measures,
p 281
where 120 beds are superposed on one another, exclusive of a great many
which are less than a foot in thickness; the coal beds at Johnstone, in
Scotland, and those in the Creuzot, in Burgundy, are some of them,
respectively, thirty and fifty feet in thickness,** while in the forests of
our temperate zones, the carbon contained in the trees growing over a
certain area would hardly suffice, in the space of a hundred years, to cover
it with more than a stratum of seven French lines in thickness.
Pages:
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592