210 The Palaeontological Record. II. Plants 
Selaginellae takes place by free spermatozoa, and in the Coniferae 
by a pollen-tube, in the interior of which spermatozoa are probably 
formed ”—a, remarkable instance of prescience, for though sperma- 
tozoids have not been found in the Conifers proper, they were 
demonstrated in the allied groups Cycadaceae and Ginkgo, in 1896, 
by the Japanese botanists Ikeno and Hirase. A new link was thus 
established between the Gymnosperms and the Cryptogams. 
It remained uncertain, however, from which line of Cryptogams 
the gymnospermous Seed-plants had sprung. The great point of 
morphological comparison was the presence of two kinds of spore, 
and this was known to occur in the recent Lycopods and Water-ferns 
(Rhizocarpeae) and was also found in fossil representatives of the 
third phylum, that of the Horsetails. As a matter of fact all the 
three great Cryptogamic classes have found champions to maintain 
their claim to the ancestry of the Seed-plants, and in every case 
fossil evidence was called in. For a long time the Lycopods were 
the favourites, while the Ferns found the least support. The writer 
remembers, however, in the year 1881, hearing the late Prof. Sachs 
maintain, in a lecture to his class, that the descent of the Cycads 
could be traced, not merely from Ferns, but from a definite family of 
Ferns, the Marattiaceae, a view which, though in a somewhat crude 
form, anticipated more modern ideas. 
Williamson appears to have been the first to recognise the 
presence, in the Carboniferous flora, of plants combining the charac- 
ters of Ferns and Cycads'. This conclusion was first reached in the 
case of the genera Heterangium and Lyginodendron, plants, which 
with a wholly fern-like habit, were found to unite an anatomical 
structure holding the balance between that of Ferns and Cycads, 
Heterangium inclining more to the former and Lyginodendron to the 
latter. Later researches placed Williamson’s original suggestion on 
a firmer basis, and clearly proved the intermediate nature of these 
genera, and of a number of others, so far as their vegetative organs 
were concerned, This stage in our knowledge was marked by the 
institution of the class Cycadofilices by Potonié in 1897. 
Nothing, however, was known of the organs of reproduction of 
the Cycadofilices, until F. W. Oliver, in 1903, identified a fossil 
seed, Lagenostoma Lomaxi, as belonging to Lyginodendron, the 
identification depending, in the first instance, on the recognition 
of an identical form of gland, of very characteristic structure, on the 
vegetative organs of Lyginodendron and on the cupule enveloping 
the seed. This evidence was supported by the discovery of a close 
anatomical agreement in other respects, as well as by constant 
1 See especially his ‘‘ Organisation of the Fossil Plants of the Coal-Measures,” Part xm, - 
Phil. Trans. Royal Soc. 1887, s. p. 299. 
