52 THE MIGRATION OF BIRDS. 



a centre of dispersal in India, due to Post-Pliocene 

 Arctic emigration, which spread by no conceivable 

 way to South America ! In the Snares and Chatham 

 Isles Scolopax auklandica is a resident ; in New 

 Zealand we find ^gialitis nova zelandice, and Chara- 

 drius obscurus, the latter breeding on the mountains 

 and wintering on the plains ; whilst in Australia 

 Charadrius austraUs may be given as an instance. 

 Now, I think, after having seen that some species 

 even at the present day migrate across the world from 

 north to south, that others are isolated and seden- 

 tary in the Southern Hemisphere, having allowed 

 their migratory impulses to lapse altogether, whilst 

 others yet again breed as far to the south in the 

 Southern Hemisphere as suitable land occurs, and 

 pass north to winter, we are driven to the conclusion 

 that Inter-Polar Migration amongst the Chara- 

 DRiiD.^ must have extensively prevailed in remote 

 ages. It should also be remarked that none of 

 these birds pass north of the Equator to winter — a 

 fact which in itself seems to suggest a South Polar 

 origin, whilst the number of Arctic species that winter 

 south of the Equator is very considerable, and seems 

 to show a lingering attachment to an ancient home. 

 Much evidence might also be given to show that 

 the Anatid^, or Ducks, and a portion at least of the 

 Turdinae {Merula and Turdus, or their common 

 ancestors), have in past ages been Inter-Polar like- 

 wise. The HirundiniDtE, or Swallows, seem to be 

 an Antarctic group which have comparatively 

 recently become almost Inter-Polar in their migra- 



