356 The Former Climate of the Polar Regions. [June, 
palm-like cycadeæ and conifer, the representative species of 
which now flourish in the neighborhood of the tropics. This 
already leads to the supposition of a warm climate, which sup- 
position is further confirmed by a comparison with the European 
fossil flora of the same date, which indicates that the climate of 
Spitzbergen did not then materially differ from that of Central 
Europe. 
The Swedish expeditions have also succeeded in obtaining, 
partly from Greenland and partly from Spitzbergen, from two 
separate epochs of the Cretaceous era, extensive collections of 
fossil plants, lately described by Professor Heer in the Trans- 
actions of the Royal Swedish Academy. By this we have been 
enabled not only to determine the epoch when differences of 
climate first began to show themselves on the surface of the earth, 
but also pretty closely to follow an extremely remarkable change 
in the appearance of the vegetable world which took place dur- 
ing the course of that period. 
Within the polar basin we meet with the lowest division of 
the Cretaceous age on the north side of the Noursoak peninsula, 
in Northwestern Greenland. The crown of the hills is here 
composed of black, ancient lava-streams and immense beds © 
volcanic tuff, hardened in process of time into solid rock. 
Over these volcanic formations now rests a covering of per- 
petual ice, and beneath them on the sea-shore vast strata of sand 
are discovered, containing inconsiderable coal-beds, interstratified 
with clay-beds and a fine-grained argillaceous shale singularly 
fitted for preserving the ‘impressions of fossils that have been 
imbedded in it. These plants belong to the lowest portion of 
the Cretaceous age, and among the collections brought from this 
spot, Heer has succeeded in distinguishing seventy-five different 
species, among which are thirty ferns, nine cycadex, and seven- 
teen conifere. i 
The third part of the ferns belongs to one genus, Gleichema, 
which still flourishes in the neigborhood of the tropics and 
warmer parts of the temperate zone, and the same remark holds 
good of the cycadez, most of which are referable to the genus 
Zamia, species of which we meet with within the tropics, as also 
of the conifers, some of which are nearly related to forms still ex- 
isting in Florida, Japan, and California. From this Heer draws — 
the conclusion, that in the early part of the Cretaceous period ee 
the climate of the now ice-covered Greenland was somewhat like 
that which now prevails in Egypt and the Canary Isles. 
