TRANSACTIONS OF SECTION K. 1005 
departures from the ordinary course of angiospermous development occur in 
families some of which haye been believed on other grounds to be among the most 
primitive Dicotyledons. 
EVIDENCE OF DescENT DERIVED FROM FossiL Botany. 
At the beginning of this Address I spoke of the importance of the comparatively 
direct evidence afforded by fossil remains as to the past history of plants. It may 
be of interest if I endeavour to indicate the directions in which such evidence 
seems at present to point. 
It was Brongniart who in 1828 first arrived at the great generalisation that 
‘nearly all of the plants living at the most ancient geological epochs were 
Cryptogams,’! a discovery of unsurpassed importance for the theory of evolution, 
though one which is now so familiar that we almost take it for granted. Those 
paleozoic plants which are not Cryptogams are Gymnosperms, for the angiospermous 
flowering plants only make their appearance high up in the secondary rocks. 
Even the Wealden flora, recently so carefully described by Mr. Seward, one of 
the secretaries to this section, has as yet yielded no remains referable to Angio- 
sperms, though this is about the horizon at which we may expect their earliest 
trace to be found. 
Attention has already been called to the enormous antiquity of the higher 
Cryptogams—the Pteridophyta—and to the striking fact that they are accompanied, 
in the earliest strata in which they have been demonstrated with certainty, by 
well-characterised Gymnosperms. The Devonian flora, so far as we know it, 
though an early, was by no means a primitive one, and the same statement applies 
still more strongly to the plants of the succeeding Carboniferous epoch. The 
palzozoic Cryptogams, as is now well known, being the dominant plants of their 
time, were in many ways far more highly developed than those of our own age; 
and this is true of all the three existing stocks of Pteridophyta, Ferns, Lycopods, 
and Equisetinez. 
We cannot, therefore, expect any direct evidence as to the origin of these groups 
from the paleeozoic remains at present known to us, though it is, of course, quite 
possible that the plants in question have sometimes retained certain primitive 
characters, while reaching in other respects a high development. For example, the 
general type of anatomical structure in the young stems of the Lepidodendrex was 
simpler than that of most Lycopods at the present day, though in the older trunks 
the secondary growth, correlated with arborescent habit, produced a high degree of 
complexity. On the whole, however, the interest of the paleozoic Cryptogams 
does not consist in the revelation of their primitive ancestral forms, but rather in 
their enabling us to trace certain lines of evolution further upward than in recent 
plants. From the Carboniferous rocks we first learn what Cryptogams are capable 
of. In descending to the early strata we do not necessarily trace the trunk of the 
genealogical tree to its base; on the contrary, we often light on the ultimate twigs 
of extensive branches which died out long before our own period. 
In a lecture which I had the honour of giving last May before the Liverpool 
Biological Society, I pointed out how futile the search for ‘ missing links’ among 
fossil plants is likely to be. The lines of descent must have been so infinitely 
complex in their ramification that the chances are almost hopelessly great against 
our happening upon the direct ancestors of living forms. Among the collateral 
lines, however, we may find invaluable indications of the course of descent. 
Fossil botany has revealed to us the existence in the Carboniferous epoch of a 
fourth phylum of vascular Cryptogams quite distinct from the three which have 
come down—more or less reduced—to our own day. This is the group of 
Sphenophyllez, plants with slender ribbed stems, superposed whorls of more or less 
wedge-shaped leaves, and very complex strobili with stalked sporangia. The 
group to a certain extent combines the characters of Lycopods and Horsetails, 
resembling the former in the primary anatomy, and the latter, though remotely, in 
external habit and fructification. Like so many of the early Cryptogams, Spheno- 
1 Williamson, Remétniscences of a Yorkshire Nataralist, 1896, p. 198. 
