EMIGRATION AND EVOIUTION 121 



I have already alludecl to what I beheve to be two 

 very interesting rincient routes of migration, which 

 in still more remote ages were obviously routes of 

 emigration. One of these extended between India 

 and South Africa across the Indian Ocean ; the 

 other as surely extended between Eastern Asia 

 and New Zealand, by way of New Caledonia and 

 Norfolk Island. The Orange-legged Hobby {Falco 

 amurensis) is one of the last surviving instances 

 of a fly-line across the Indian Ocean ; but the 

 number of species isolated in South Africa, allied 

 to Indian species, testify to its ancient importance, 

 and mark the route, the only feasible route of their 

 emigrations, between these two countries. The only 

 other land connection between India and Africa is 

 by way of Arabia ; but if w^e were to assume such 

 to have been the route (and there is not the slightest 

 evidence in its favour), we are confronted with the 

 difficulty of transporting thoroughly tropical and 

 south temperate species into northern zones, and 

 tlien isolating them in South Africa without leaving 

 a solitary trace or relic of their dispersal in the 

 intervening country. Besides, some of the most 

 interesting species, decidedly Oriental in type, are 

 isolated in Madagascar, or on the Inter-Indian 

 islands. Thus, in the Seychelles we find isolated 

 species of such thoroughly Oriental genera as 

 Copsychus and Hypsipetes ; in Mauritius and Rod- 

 riguez species of Palaornis. It needs then no great 

 stretch of imagination to recall those past ages, 

 probably towards the close of the Tertiary Period, 



