474 Oliver . — The Ovules of the older Gymnosperms . 
ground in its turn becomes the scene of active operations. 
In time the summit is little more than a land-mark, and 
is ultimately denuded away. 
Whilst the consideration of these seeds from the palaeozoic 
rocks, together with those of recent Cycads and Taxaceae, 
tends to confirm the view that is held on many hands as 
to their common origin, it is evident that even the oldest 
forms show a marked advance on the condition that probably 
obtained in their pteridophytic ancestors. Whilst the work 
of recent years has tended to carry the lower limit of the 
Gymnosperms deep down into the Ferns, we are still in search 
of fern-sporangia exhibiting a tendency or capacity for seed- 
like adaptation. Along the line of the Lycopodineae such 
structures have become known to us in Lepidocarpon , the evi- 
dent strobilus of a Lepidodendron bearing seed-like structures 1 . 
But in view of the probable Filicinean affinities of the Cycads 
and of the other Gymnosperms, Lepidocarpon is only of value 
for the moment as an analogy. It cannot be supposed that 
the Gymnosperms were evolved from the Lycopodinean 
phylum. A structure standing in the same relation to the 
probable fern-like ancestors of the Gymnosperms as Lepido- 
carpon does to the Lycopodineae has yet to be discovered. 
Whether the transverse section of an unidentified sporangium 2 
showing a belt of tracheal elements between the sporangial 
wall and the mass of developing spores is likely to furnish 
a clue must await the identification of that sporangium. In 
any case the condition of vascularity in a fern-sporangium, 
which this specimen proves to have actually existed, may 
have been an important antecedent to the evolution of the 
vascular nucellus that played so considerable a part among 
the earlier Gymnosperms, and from which it may be reason- 
ably supposed the ordinary Coniferous type of nucellus has 
been derived. 
University College, London, 
January , 1903. 
1 D. H. Scott, The Seed-like Fructification of Lepidocarpon. Phil. Trans., 1901, 
p. 291. 
2 A Vascular Sporangium, The New Phvtologist, Vol. i, p. 60. 
