RANGE BASE OR REFUGE AREAS 39 



because they were never subjected to such vast exter- 

 minating conditions as have entirely removed every one 

 of these their northern descendants. If the range base 

 was beyond the limits of exterminating influences (either 

 connected by migration or continuous breeding area) the 

 species or the type survived ; if entirely within such fatal 

 limits, just as surely did such types or species vanish 

 for ever ; for the Law of Dispersal {conf. p. 60) in the 

 Northern Hemisphere forbids all southern emigration 

 either to increase breeding area, or to escape adverse 

 climatic change, or unfavourable conditions of life. One 

 of the most graphic examples of the inability of a fauna 

 to escape from utter extermination is afforded at the 

 present time in New Zealand. Let the reader peruse 

 Mr. W. H. Smith's sad account of the extermination of 

 birds in that country (//'/>, 1893, pp. 509 — 521), and he 

 will be speedily convinced of the truth of the axiom 

 that species never " retreat " from unfavourable con- 

 ditions only by extermination. In the case of a wide- 

 ranging dominant species, only such portions of the 

 species are affected as are subject to the adverse con- 

 ditions ; but if the species occupies a narrow area 

 nothing can save it from utter extermination if the 

 adverse conditions continue. 



Of the rich and magnificent fauna of Euro-Asia what 

 an utterly insignificant remnant has been preserved to 

 us, how devastating has been the result of the Glacial 

 Epoch upon these, some of the highest as well as the 

 more archaic forms of life ! The present distribution in 

 Africa of many of the larger carnivores (such as the 

 lion, panther, cheetah, jackal, and hyaena) may, however, 

 be slightly due to a Pleistocene range contraction from 



