COAL PLANTS. IOI 
tender bodies are as little suited as those of all other 
mosses for being preserved in a fossil state, paleontology 
can give us no information about this. 
We learn from the science of petrifactions much more 
than we do in the case of Mosses of the importance which 
the second branch of Prothallus plants—that is, Ferns— 
have had in the history of the vegetable world. Ferns, or 
more strictly speaking, the “plants of the fern tribe” 
(Filicineze, or Pteridez, also called Pteridophyta, or Vascular 
Cryptogams), formed during an extremely long period, 
namely, during the whole primary or palzeolithic period, the 
principal portion of the vegetable world, so that we may 
without hesitation call it the era of Fern Forests. From the 
beginning of the Devonian period, in which organisms 
living on land appeared for the first time, namely, during 
the deposits of the Devonian, Carboniferous, and Permian 
strata, plants like Ferns predominated so much over all 
others, that we are justified in giving this name to that 
period. In the stratifications just mentioned, but above all, 
in the immense layers of coal of the Carboniferous or coal 
period, we find such numerous and occasionally well pre- 
served remains of Ferns, that we can form a tolerable vivid 
picture of the very peculiar land flora of the paleolithic 
period. In the year 1855 the total number of the then 
known paleeolithic species of plants amounted to about a 
thousand, and among these there were no less than 872 Ferns. 
Among the remaining 128 species were 77 Gymnosperms 
(pines and palm-ferns), 40 Thallus plants (mostly Algze), and 
about 20 not accurately definable Cormophyta (stem-plants). 
As already remarked, Ferns probably developed out of the 
tower liverworts in the beginning of the primary period. 
