149 
FOSSIL CLIMATES. 
A. C. SEWARD, M.A, F:G.S., 
St. Fohn's College, Cambridge. 
WirHour attempting to crowd into a short paper an undue number 
of facts or theories, we may begin by noting what some of the 
earlier geologists and palzobotanists have to say with regard to 
climates of past ages. Fossil plants, rather than animals, will be 
taken as guides in these weather retrospects ; our attention will be 
centred round them, not concerning ourselves to any great extent 
with either physical evidence or evidence afforded by fossil animals. 
For many reasons, theories as to climate in past time were first pro- 
pounded with reference to the Carboniferous period, or rather the 
uppermost division of that system—the Coal Measures. Perhaps 
even to-day the climate of that age has the greatest fascination for 
us, as more wrapped in obscurity and affording less valuable evidence 
than the plant-bearing beds of more recent systems, whose fossils, 
much more closely allied to living forms, tell us in more certain 
terms of changes of climate well nigh incredible. The botanist 
Antoine de Jussieu, in the early part of last century, was one of the 
first to draw any conclusions as to Carboniferous climate from the 
fossil plants so abundant and widely distributed in the Coal seams and 
associated strata. He pointed to tropical genera as the nearest 
relatives of coal plants, this relationship suggesting tropical con- 
ditions at the time when these plants formed the Carboniferous 
Orests. Passing to the present century, we find Adolphe Brongniart, 
whom we may regard as the Father of paleobotany, referring to 
Certain algze in pre-cretaceous strata as indicative of a high tempera- 
ture ; the occurrence of a fossil Sargassum (the Gulf-weed) in Sweden 
being quoted in support of his conclusions. One may note, in 
passing, the impracticability of forming any theories on such extremely 
doubtful forms as the so-called ‘fossil algze.’ 
Taking his stand on surer ground, Brongniart lays stress on the 
high percentage of vascular cryptogams in the Coal Measures 
flora—five-sixths of the whole—as compared with the very sub- 
Ordinate position which the group holds to-day. It is pointed out 
that these Carboniferous vascular cryptogams are larger than 
modern genera, and differ further in the greater development of 
their stems, both facts regarded as suggestive of warmer climate. 
The same botanist recognises the uniform character of this flora, 
from Greenland and the shores of Baffin’s Bay to localities in 
May r8or. ' 
