vi] DISTRIBUTION OF SELECTED GROUPS 111 



the following somewhat arbitrary sub-families, each 

 with a still well-marked radiating centre. Guinea- 

 fowls restricted to Africa and Madagascar. Pheasants, 

 'fowls' and peacocks essentially southern Asiatic. 

 Turkeys are peculiar to North and Central America. 

 The Tetraoiiinae are essentially holarctic : most 

 numerous in North America, e.g. prairie fowls, others 

 in tropical America ; grouse are circumpolar ; caper- 

 caillie Eurasian, also partridges ; francolins are Indo- 

 African ; quails have the widest distribution, over 

 most of the Old World, including Madagascar, and 

 even New Zealand had one, quite recently extin- 

 guished, species. 



Cuckoos are a cosmopolitan family, even New 

 Zealand possessing several kinds. Our common 

 cuckoo ranges over most of the Old World. The 

 present distribution of the various sub-families yields 

 no tangible results, since most of them have allied 

 genera in Asia, Africa and South America, and there 

 is no convincing ground for assuming that their 

 original centre was Eastern Asia. The Turacoes or 

 helmet-cuckoos are an entirely Ethiopian family. 



Parrots seem to have originated in the Aus- 

 tralian region, which alone contains members of all 

 the sub-families and the more ancient forms, whilst 

 other continents possess only members of the family 

 Psittaciae. South America has the structurally most 

 advanced genera. India and Africa are poor in 



