274 HIMANTOPUS. 



( . h ™ atl0 . The genus Himantopus is neither an Arctic nor a Tropical group of birds. Every 



species breeds in the Temperate Regions, but the breeding-range of three of them extends 

 also to the tropics. They are distributed as follows : — 



Temperate North America 1 



Temperate South America 2 



New Zealand and Temperate Australia 4 



Temperate species — 7 



Temperate and Tropical N. America 1 



Temperate Eurasia and Temperate and Tropical Africa . 1 



Tropical Africa and Tropical and Temperate Eurasia . . 1 



Temperate and Tropical species — 3 



Sandwich Islands 1 



Tropical species — I 



Species of Himantopus — 11 



Origin of 

 species. 



Commence- 

 ment of 

 emigrations. 



Let us endeavour to trace the history of the ancestral form from which the eleven 

 species now forming the genus Himantopus are descended, and let us try to follow its 

 emigration, from the period when it consisted of only one species living on the shores of 

 the north polar sea, down to the present time when its descendants have become eleven 

 species scattered over the greater part of the globe. 



Probably the first split in the circle of circumpolar birds was the intervention of a 

 glacier, stretching from the north pole down the mountains of Greenland. The semi- 

 isolation caused by the stoppage of interbreeding between the birds of the Atlantic coast of 

 America and that of Europe must naturally have produced a differentiation between the 

 birds of Grinnel-Land and Scandinavia, and there is reason to believe that the former 

 became Stilts and the latter Avocets ; but inasmuch as interbreeding could take place 

 between the birds of each bay and those of the next along the whole line in one direction, 

 it can scarcely be doubted that at first the Stilts were connected by a series of intermediate 

 forms with the Avocets. The next cause of isolation (which was probably complete) was 

 most likely a glacier stretching across the north pole from the Rocky Mountains, either to 

 Novaya Zemlya or to the mountains of Eastern Siberia. This must soon have been 

 followed by the evacuation of the Polar Basin, and the emigration of the birds in four 

 parties along the four shores leading to the south. The causes already enumerated must 

 have produced an emigration of Stilts along one coast of the Atlantic, an emigration of 

 Avocets along the other, whilst the emigration along the two coasts of the Pacific must 

 have consisted on the one side of Avocets with a strong strain of Stilt in them, and on the 

 other of Stilts with a strong strain of Avocet blood. 



The next step to take is to examine the eleven species of the genus, and ascertain if 



