VI. 



GEOGRAPHICAL DISTKIBUTION OP ORGANIC 

 BEINGS. 



OrWn of W^ ^^'6 thus brought to the question which 



Species, has been largely discussed by naturalists, name- 

 page • Yy^ whether species have been created at one or 

 more points of the earth's surface. Undoubtedly there 

 are many cases of extreme difficulty in understanding how 

 the same species could possibly have migrated from some 

 one point to the several distant and isolated points where 

 now found. Neyertheless the simplicity of the yiew that 

 each species was first produced within a single region 

 captiyates the mind. He who rejects it rejects the vera 

 causa of ordinary generation with subsequent migration, 

 and calls in the agency of a miracle. It is universally 

 admitted that in most cases the area inhabited by a 

 species is continuous ; and that, when a plant or animal 

 inhabits two points so distant from each other, or with an 

 interval of such a nature, that the space could not have 

 been easily passed over by migration, the fact is given as 

 something remarkable and exceptional. The incapacity 

 of migrating across a wide sea is more clear in the case of 

 terrestrial mammals than perhaps with any other organic 

 beings ; and, accordingly, we find no inexplicable in- 

 stances of the same mammals inhabiting distant points 



