276 REVIEWS. 



frigid and rigorous or comparatively mild ? Were Europe 

 and the United States simply arctic and to be compared with 

 the present Greenland and Spitzbergen, as the school of 

 Agassiz maintains? Or should the comparison rather be 

 made with southern New Zealand, where Tree-ferns almost 

 overhang the terminal moraines of existing glaciers, in a cli- 

 mate which is neither cold nor warm? Saporta maintains 

 the latter, and he is not alone. He insists that the high Alps 

 and the Pyrenees are not the types of glacial Europe gener- 

 ally ; that the arctic animals and plants, and the rigorous cli- 

 mate which we associate with these, belonged only to the close 

 neighborhood of glaciers, but that the valleys below enjoyed 

 a climate even milder than now, although vastly more humid. 

 So, likewise, Mr. Ball (in a lecture recently delivered before 

 the Royal Geographical Society of Great Britain) ventures to 

 affirm that, even during the pei'iod of maximum cold, the 

 highest ridges of the Alps were not completely covered with 

 snow and ice ; for we still see, by the appearance of the sur- 

 face, the limit above which the ancient ice did not reach ; and 

 in the middle zone the slopes that rose above the ancient gla- 

 ciers had a summer climate not very different from that which 

 now prevails. And he concludes that the effect on the growth 

 of plants in the Alps was to lower the vertical height of the 

 zones of vegetation only one or two thousand feet. 1 



This would seriously affect the forests of Europe, but would 

 not permanently disturb the alpine and sub-alpine vegetation. 



Yet cold it must have been when the reindeer and musk-ox 

 roamed over the plains of central Europe, and when the ele- 

 phant or mammoth and even the rhinoceros which accom- 

 panied them, were equally clad with a thick coat of hair. 

 But, says Saporta, with the remains of these very animals 

 from which a frigid arctic climate is inferred, occur also, in 

 the alluvia of the Somme and the Seine, those of an elephant 

 nearly related to the Indian species, the hippopotamus of the 

 African rivers, and the hyena of the Cape ; and the vegetable 



1 But Mr. Ball is fairlv astounding: when he assumes that our arctic- 

 alpine flora may have been the flora of high mountains at low latitudes in 

 the carboniferous period. 



