246 ELEMENTS OF SCIENCE 



America on the one hand, and (6) Europe, with North 

 Africa and Asia, on the other, are similarly, though less 

 strikingly, characterised. Various species which now 

 inhabit one or other of those areas closely resemble 

 certain tertiary fossils also found therein. 



The botanical regions into which the world is divisible 

 are ten in number, (i) Arctic; (2) Boreal (or Europe, 

 Asia and America, from the Arctic circles to the Pyrenees, 

 the Alps, the Balkans, the Himalayas and North America 

 to the tropic of Cancer) ; (3) Caucasia, or the shores of 

 the Mediterranean up to the Pyrenees, Alps, and Balkans, 

 with North Africa and North-Western Asia ; (4) Ethio- 

 pia or Africa southwards to the tropic of Capricorn, with 

 Madagascar and Southern Arabia ; (5) South Africa to 

 the Cape; (6) Indo- Malayan, or the Indian Archipelago ; 

 (7) Australian; (8) Neotropical, or tropical South 

 America and the West Indies; (9) Patagonian, or 

 America south of the Southern tropic ; and (10) Antarctic, 

 or Kerguelen's land. 



The geographical range of living creatures, even of the 

 same class, is often most unequal. Thus the flame-bearing 

 humming-bird is confined to the crater of the extinct 

 volcano Chiriqui, in America, while the crow ranges over 

 almost the whole world except South America. Different 

 animals and plants are obviously influenced as to their 

 extent of range by their different requirements as to 

 heat, light, moisture, &c. 



Beside geographical distribution, living organisms have 

 a vertical or Bathymetrical distribution. Thus in the 

 tropics, palm, bananas, &c., grow luxuriantly in the low- 

 lands. At a moderate elevation they give place to ever- 

 greens, then these to a belt of deciduous trees, then we 

 find only shrubs, grasses, Alpine plants, and mosses. The 

 camel is an animal of the plains, but the llama will 



