THE FACTORS OF DISTRIBUTION 71 



leaved trees, and these to conifers, dwarf Alpine shrubs, 

 mosses, and lichens, and, finally, to perennial snow. 

 As the snow-line falls gradually from 18,000 or 16,000 

 feet above sea-level in Equatorial regions to 14,000 and 

 1 1 ,000 feet in the Warm Temperate Zone ; to 8000 and 

 4000 in Cold Temperate and Sub-Arctic regions; 2000 in 

 the Arctic, and to sea-level in Polar regions, the actual 

 altitudes of these zones will gradually diminish towards 

 the Poles; while mountains in higher latitudes will, of 

 course, start at their bases with the vegetation of the 

 plain at that latitude. 



The following nine altitudinal zones are recognisable 

 on equatorial mountains: 



1. Zone of 'Palms and Bananas (sea-level to 1900 feet), 

 corresponding to the Equatorial horizontal Zone. 



2. Zone of Tree-ferns and Figs (1900 to 3800 feet), 

 corresponding to the Tropical Zone, with multitudes of 

 Peppers, Aroids, and Orchids, the Figs replaced by 

 arborescent Urticacece in the islands of the South Pacific, 

 and Cinchonas being characteristic in the Andes. 



3. Zone of Myrtles and Laurels (3800-5700 feet), corre- 

 sponding to the Sub-tropical Zone, with Magnolias, 

 Camellias, Ericacece, Evergreen Oaks, and other glossy, 

 thick-leaved evergreens, and Acacias. 



4. Zone of Evergreen Trees (5700-7600 feet), corre- 

 sponding to the Warm Temperate Zone, with many showy 

 LegwninoscB, Myrtacece, etc. 



5. Zone of Deciduous Trees (7600-9500 feet), corre- 

 sponding to the Cold Temperate Zone, but only repre- 

 sented, between the Tropics, on elevated plateaux. 



6. Zone of Conifers (9500-11,500 feet), corresponding 

 to the Sub- Arctic Zone. " 



7. Zone of Alpine Shrubs or of Rhododendrons (11,500- 

 13,300 feet), corresponding to the Arctic Zone, with 

 Befaria replacing Rhododendron in South America, and 

 dwarf Willows, Junipers, and Ribes in the Himalayas. 



8. Zone of Alpine Herbs (13,300 feet to the snow-line), 

 corresponding to the Polar Zone, with vegetation in 

 patches, chiefly of low-growing, wiry, large-flowered 

 perennials. 



9. Zone of Mosses and Lichens (above the snow-line). 

 Many factors interfere with the regularity of this zona- 

 tion, such as the equalising influence of ocean surrounding 

 such a mountain -peak as Teneriffe ; the greater exposure 



