EXTERMINATION IN ANIMAL LIFE. 291 



not only in the heat of the low country, but also on the top of 

 Mount Troodos, " quite at home among the snow," and as com- 

 mon as in what he imagined to be the more congenial climate.* 

 This gives us some clue to the antiquity and survival of the 

 Myriapocla, fossil remains of which have been found in the Old 

 Bed Sandstone of Scotland. That well-known insect belonging 

 to the Thysanura (Campodea staphylinus) has been found by Dr. 

 Sharp at midsummer, near the shores of the Mediterranean, in 

 company with the subtropical White Ants, and within a day or 

 two of the same time he noticed it to be abundant on the actual 

 summit of Mount Canigou, one of the higher Pyrenees, where 

 the conditions were almost arctic! This creature has been sup- 

 posed to be the nearest living representative of a primitive or 

 ancestral insect. The mountain fern (Cystopteris fragilis), 

 " while not objecting to Italian heat," yet flourishes at the base 

 of the Biffelhorn in Switzerland, at the elevation of 9000 feet 

 above the sea.J 



It is necessary to remember that the causes which produced 

 the last glacial epoch are still operative in the present as well as 

 having been so in the past. A long series of glacial visitations 

 consequent on the sequence of natural phenomena is what we 

 must endeavour to visualize. Sir Robert Ball calculates that 

 the intervals between their recurrence may, it is true, be not 

 unfrequently 21,000 years, but the period will often be far 

 greater. § The mind is appalled with the idea of what a vast 

 destruction of living types, both animal and vegetal, must have 

 taken place during these icy invasions. Many forms doubtless 

 escaped, as we can see by the survivals of to-day, but others must 

 have perished in whole series, leaving not a wrack behind. In the 

 time to come, when the material civilization of Northern Europe 

 will be annihilated under the thick mantle of ice incidental to a 

 new glacial epoch, science in an organized form will watch and 

 record its insidious approach. A zoological literature of the 

 near past will then exist, and species, if destroyed, will be missed, 

 and their obituaries written. The museums and libraries of 



:; - 'Cambridge Nat. Hist.' vol. v. pp. 32-3. 



f Loc. cit. p. 183. 



I Hinchliff, ' Over the Sea and Far Away,' p. 261. 



§ ' The Cause of an Ice Age,' p. 156. 



