Seward: The Jurassic Flora of Yorkshire. &Q 
It is in regard to such considerations as these that the botanist 
who concerns himself with the floras of the past ought to look 
for assistance from geologists. The paleobotanist should not 
be content with identifying the specimens submitted to him, 
but he should endeavour to extend his researches beyond the 
limits of mere systematic enquiry. It is important to do one’s 
best to compile a list of species which may be cited with con- 
fidence by those who wish to make use of palaobotanical 
data ; but in favourable circumstances it is possible to advance 
our work a stage further. If we are able to obtain petrified 
specimens in good preservation, we are not only in a much 
better position to ascertain the systematic position of the 
plants, but we have important information placed in our 
hands from which to reconstruct, though it may be in faint 
outline, the conditions under which the plants grew. In the 
case of the rich store of petrified samples of the Palaeozoic 
vegetation preserved in the coal seams of Lancashire, York- 
shire, and other parts of England, it has been possible partially 
to revivily the Coal forests, and to form opinions as to the nature 
of the conditions under which the plants carried on their life. 
Having pointed out the need of additional data, and the 
uncertainty of some of our determinations, I pass on to con- 
sider in a few words the general nature of the Jurassic vegetation 
so far as this is possible with the data available. The Yorkshire 
coast flora is characterised by the abundance of Ferns and 
Cycads and certain types of Conifers, but we are not as yet in 
a position to make any definite statement as to the relative 
abundance of these different groups. It is also probable that 
the Ginkgoales played a fairly prominent part in the composi- 
tion of the vegetation. The most interesting fact in regard 
to the Jurassic ferns 1s that they afford strong presumptive 
evidence in support of the view that their nearest living allies 
are to be sought in the southern hemisphere. As reg sards the 
Cycads, comparison with recent genera is rendered more 
difficult because of the greater gulf between recent members 
of the group and those which flourished in the Jurassic era. 
There can, however, be no reasonable doubt that the Cycads 
of to-day are derived from an ancient stock which produced 
also Williamsonia and other Jurassic genera. Here, again, the 
recent plants most nearly akin to those of the Mesozoic floras 
are chiefly characteristic of southern and warmer regions. 
The same general statement is applicable to the relation of 
some of the Jurassic conifers to recent types. Finally, in the 
genus Ginkgo of the Jurassic flora, we have a member of a group 
which would probably have ceased to be represented among 
living plants were it not for the fact that the recent species 
has been long held in veneration in the far East as a sacred 
tree. With these southern forms there grew in_ profusion 
1gi1 Feb. 1. 
