372 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
Our subject covers the botany of the whole Paleozoic epoch from 
the oldest rocks in which plant remains have been found up to the 
close of the Permian formation. Our knowledge, however, of the 
different periods embraced within this immense range of time is so 
unequal that no general description of Paleozoic vegetation can be 
attempted. In the Silurian, for example, vegetable fossils are so 
scanty that the data are altogether inadequate to give any idea of the 
flora of that formation. The Devonian is far richer and of great 
botanical interest, but its flora urgently needs a critical revision in 
the hght of modern knowledge. It is only when we come to the 
Carboniferous that the evidence becomes abundant and satisfactory, 
and it is from this formation that our conception of Paleozoic floras 
has been essentially derived. 
In considering the plant world at such a remote epoch we are pre- 
pared to find that the limits and relative development of the various 
classes were very different from those to which we are accustomed in 
the recent flora. There is no evidence that the Angiosperms, now 
the dominant class in the vegetable kingdom, existed in Paleozoic 
times; on the contrary, their first traces only appear far on in the 
Mesozoic epoch. Although their history may probably extend much 
further back than is shown by our present records, there is no reason 
to suppose that their eyolution, as a distinct phylum, had begun in 
Paleozoic times. On the other hand Gymnosperms, and more primi- 
tive seed plants allied to Gymnosperms, were immensely abundant, 
though belonging, with few exceptions, to families now extinct. The 
Pteridophyta, while not so predominant as has commonly been sup- 
posed, played an important part, and some of their families attained 
a development far exceeding anything that their recent allies can 
show. As regards the lower classes of plants, while we have scarcely 
any knowledge of Paleozoic Bryophyta, there is evidence that Bac- 
teria were present and that Fungi were abundant, though the re- 
mains of the latter have not as yet proved of any great botanical 
interest. The Algz are somewhat better known, but here also well- 
characterized specimens are few. 
The land vegetation of the Paleozoic period, from the Devonian 
onward, was in part Pteridophytic and in part Spermophytic. In 
the light of our present knowledge it appears probable that in the 
Carboniferous, at all events, the latter element was predominant, and 
possibly this may already have been the case even in Devonian times. 
The conception of the Paleozoic age as the reign of the Cryptogams, 
current from the time of its author Brongniart down to our own day, 
has lost its validity, owing to the increasing evidence for the seed- 
bearing character of a large proportion of the forms hitherto classed 
