130 CIRCUMSTANCES FAVOURABLE TO THE [Chap. IV. 



ready have been victorious over many competitors, will be 

 those that will spread most widely, and will give rise to 

 the greatest number of new varieties and species. They 

 will thus play a more important part in the changing 

 history of the organic world. 



In accordance with this view, we can, perhaps, under- 

 stand some facts which will be again alluded to in our 

 chapter on Geographical Distribution; for instance, the 

 fact of the productions of the smaller continent of Aus- 

 tralia now yielding before those of the larger Europajo- 

 Asiatic area. Thus, also, it is that continental produc- 

 tions have everywhere become so largely naturalised on 

 islands. On a small island, the race for life will have 

 been less severe, and there will have been less modifica- 

 tion and less extermination. Hence, we can understand 

 how it is that the flora of Madeira, according to Oswald 

 Heer, resembles to a certain extent the extinct tertiary 

 flora of Europe. All fresh-water basins, taken together, 

 make a small area compared with that of the sea or of the 

 land. Consequently, the competition between fresh-water 

 productions will have been less severe than elsewhere; 

 new forms will have been there more slowly produced, 

 and old forms more slowly exterminated. And it is in 

 fresh-water basins that we find seven genera of Ganoid 

 fishes, remnants of a once preponderant order: and in 

 fresh water we find some of the most anomalous forms 

 now known in the world as the Ornithorhynchus and 

 Lepidosiren which, like fossils, connect to a certain ex- 

 tent orders at present widely sundered in the natural 

 scale. These anomalous forms may be called living fos- 

 sils; they have endured to the present day, from having 

 inhabited a confined area, and from having been exposed 

 to less varied, and therefore less severe, competition. 



To sum up, as far as the extreme intricacy of the 



