of the Polar Regions. 65 



We may add other proofs to confirm our assertion. From the 

 character of the flora of Spitzbergen at the Miocene period 

 we may conclude that under 79° N. latitude the mean tempe- 

 rature of the year was 5° C. (= 41° F.) ; at the same epoch 

 that of Switzerland was 21° C. (= 69°-8 F.), judging from 

 the analogy of floras. There is consequently a difference of 

 16° C. ( = 28°-8 F.) ; and for each degree of latitude the mean 

 temperature has fallen 0°-5 C. ( = 0°-9 F.) From this it fol- 

 lows that at Spitzbergen, at 78° N. latitude, the mean was 

 5°-5 C. (= 41°-9 F.), in Greenland, at 70°, it was 9°-5 C, ( = 

 49°* 1 F.), and in Iceland and on the Mackenzie, in latitude 65°, 

 it was ll°-5 C. ( = 52°'7 F.) These data suffice to explain the 

 character of the flora of this period *. 



The difference of temperature between Switzerland, in N. 

 lat. 47° (brought by calculation to that of the sea-level), and 

 Spitzbergen, in N. lat. 78°, is at present 20°-6 C. ( = 37°-08 F.), 

 which gives a diminution of 0°"66 C. ( = 1°'2 F.) for each 

 degree of latitude. It is therefore evident that at the Miocene 

 epoch the temperature was much more miiform, and that the 

 mean heat diminished much more gradually in proportion as 

 the pole was approached, so that then the isothermal line of 

 0° ( = 32° F.) fell upon the pole, whilst now it is situated 

 under 58° N. 



It has been asserted that at the Miocene epoch currents 

 might transport wood and vegetable remains to great distances, 

 as is the case now, and that it is very possible that the plants 

 which we find in the fossil state in the deposits of the polar 

 regions may have been carried there in an analogous manner, 

 and may not have lived on the soil where we find their 

 remains. This notion cannot be admitted, as will be easily 

 seen if we consider : — 1, the perfect preservation of the 

 leaves ; 2, the enormous accumulation of fossil plants in the 

 beds of siderolitic iron-ore in Greenland, associated with great 

 deposits of lignites ; 3, the fact that insects are found with 

 the plants ; and, 4, the presence of beech-leaves just issued 

 from the bud and still folded, as well as that of flowers, seeds, 

 and fruits associated with the leaves. Certain seeds are found 

 arranged in the same manner as in the berry which protected 

 them ; this evidently indicates that the berry itself was buried 

 in the mud. Now it is clear that a berry could not be carried 

 by the waves to great distances. 



Whoever will examine, without preconceived ideas, the 



* For furtlier details upon tliis subject consult the ' Flore fossile des 

 Regions polaires,' by Prof. 0. Heer (Zurich, 1867), in which all the 

 plants of the Miocene epoch discovered in these countries are described 

 and figured. 



Ann. & Mag. N. Hist. Ser. 4. VoJ.i. 5 



