ave spores of two kinds, while the other two (Lycopodium and
Phylloglossum) are homosporous. Curiously enough, no certain instance
of a homosporous Palaeozoic Lycopod has yet been discovered, though
well-preserved fructifications are numerous. Wherever the facts have
been definitely ascertained, we find two kinds of spore, differentiated
quite as sharply as in any living members of the group. Some of the
Palaeozoic Lycopods, in fact, went further, and produced bodies of the
nature of seeds, some of which were actually regarded, for many
years, as the seeds of Gymnosperms. This specially advanced form of
fructification goes back at least as far as the Lower Carboniferous,
while the oldest known genus of Lycopods, Bothrodendron, which is found
in the Devonian, though not seed-bearing, was typically heterosporous,
if we may judge from the Coal-measure species. No doubt homosporous
Lycopods existed, but the great prevalence of the higher mode of
reproduction in days which to us appear ancient, shows how long a course
of evolution must have already been passed through before the oldest
known members of the group came into being. The other characters of
the Palaeozoic Lycopods tell the same tale; most of them attained
the stature of trees, with a corresponding elaboration of anatomical
structure, and even the herbaceous forms show no special simplicity.
It appears from recent work that herbaceous Lycopods, indistinguishable
from our recent Selaginellas, already existed in the time of the
Coal-measures, while one herbaceous form (Miadesmia) is known to have
borne seeds.

The utmost that can be said for primitiveness of character in Palaeozoic
Lycopods is that the anatomy of the stem, in its primary ground-plan, as
distinguished from its secondary growth, was simpler than that of most
Lycopodiums and Selaginellas at the present day. There are also some
peculiarities in the underground organs (Stigmaria) which suggest the
possibility of a somewhat imperfect differentiation between root and
stem, but precisely parallel difficulties are met with in the case of
the living Selaginellas, and in some degree in species of Lycopodium.

In spite of their high development in past ages the Lycopods, recent
and fossil, constitute, on the whole, a homogeneous group, and there is
little at present to connect them with other phyla. Anatomically some
relation to the Sphenophylls is indicated, and perhaps the recent
Psilotaceae give some suppor