30 College of Forestry 
etable origin chiefly, then such vast supplies imply a very 
massive and widely distributed vegetation. It is further 
unique from a modern point of view by reason of lacking the 
types of plants which now characterize the earth’s vegetation 
in the large. 
Several things stand out significantly for our present pur- 
pose. <A practically earth-wide tropical climate permitted a 
massive and monotonously uniform tropical vegetation to 
exist In certain situations, widely distributed over the earth. 
Judging by conditions under which peat beds form, the heavy 
vegetation which built up the coal forming peat beds must 
have occupied swamp lands and shallow waters. The pter- 
idophytes — ferns and their allies — constituted by far the 
dominant elements of the vegetation. Those branches of the 
pteridophytes whose modern representatives are popularly 
called horse-tails, or scouring rushes, and club mosses were in 
the Carboniferous period abundantly represented, especially 
by species of gigantic size and no doubt forming as conspicu- 
ous an element in the forests of that period as broad-leaved 
trees and conifers do at the present. There were no an- 
giospermous plants (1. e., none of the group embracing flow- 
ering plants), no coniferous plants of the modern gymno- 
sperm type, indeed no gymnosperms at all of any group at 
present living. ‘There were very primitive forms of seed 
plants whose vegetative structure was so fernlike, particu- 
larly in respect to leaf form, that for long they were held to 
be true ferns. Such forms as these C'ycadofilices help fill 
up the missing chapters in the story of descent. As before 
indicated, the vegetation was prevailingly heavy forest with 
ereat trees as the dominating features but with also other 
subordinate associates of shrub size, an undergrowth of her- 
baceous and woody ferns and even some ferns of climbing 
habit. It is interesting to note that thus early in geologic 
history there is shown a differentiation of growth forms in a 
forest. But though of arborescent size, it is not to be in- 
ferred that a tree-form of the Carboniferous period would 
be the biological (or ecological) equivalent of the trees which 
constitute our northeastern forests; for example, the decidu- 
