64. SECTIONAL ADDRESSES 
Felix, in 1885, suggested that Lyginopteris had cycadaceous affinities, and 
Count Solms-Laubach, in 1887, recognised the existence of types, includ- 
ing Lyginopteris, intermediate between ferns and gymnosperms. William- 
son even in 1890 held that the balance was towards the ferns, ‘ most 
probably belonging to some sphenopterid type.’ In 1903 the question 
was settled definitely by Oliver and Scott *” when they showed that L. 
oldhamium bore seeds of the Lagenostoma lomaxi form. ‘The reality of an 
intermediate group of Pteridosperms was thus proved. The position 
was attained by reference to petrified specimens, and also to incrustations, 
and the search for the male fructifications has gone on, since then, with 
marked success. Many of the male and female fructifications of these 
fern-like incrustations have been found ; and new discoveries in technique 
have materially assisted in these researches. Methods devised by the 
late Prof. Nathorst, Dr. H. Hamshaw Thomas, Prof. John Walton and 
Dr. Halle have revolutionised the study of plant incrustations and mum- 
mified specimens, so that the weapons now in the hands of the researcher 
are more numerous than ever before ; and this augurs well for the future. 
The story of the Pteridospermeae might be repeated in other groups. 
At our doors, at Rhynie, there is the chert bed which has yielded to 
Kidston and Lang plants whose structures are so distinct that they must 
be included in another special intermediate group, the Pszlophytales. 
Wieland, Florin and others have shown the existence of the Bennettitalian 
type in abundance in Mesozoic times. Hamshaw Thomas has proved 
the occurrence, in the Jurassic Caytoniales, of characters that throw con- 
siderable light on the probable ancestors of the angiosperms. While 
it may be objected that these have more botanical implications than 
geological, there is the obvious reply that anything that has a bearing on 
the elucidation of past phases of life is, of its very essence, geological. 
I do not agree that a piece of geological research must necessarily produce 
a geological map of a piece of country. One of the most pleasant aspects 
of geological work is certainly that it takes one into the field ; but specialist 
work in the laboratory is no less geological because it is also biological 
or petrological or chemical. 
FossiL PLANTS AS STRATIGRAPHICAL INDEXES. 
The outcome of the stratigraphical aspect of these researches was 
that there had occurred four distinct floras in geological times, an early 
Palzozoic, a late Palaeozoic, a Mesozoic and a Tertiary flora; and that 
there were florules by means of which smaller divisions could be recog- 
nised. ‘The degree of accuracy with which these latter may be delimited 
is still, however, open to discussion. ‘There is some evidence, also, for 
an early marine flora in pre-Cambrian and very early Palzozoic time, but, 
though apparently extensive, the types are few and many are possibly only 
inorganic growths. 
As far back as Jussieu’s time (1718) a distinction between the plants : 
of the Coal Measures and the living flora had been realised, but no — 
a Proc. BOY. 900... VOl., 735 PuA7a- 
