INTRODUCTION. xxiii 



the term Holarctio region, and conforming somewhat closely to our own 

 Arctogaean realm (supra). Oar next subfamily consists of the Semi-web-footed 

 Sandpipers or Tatlers (Totaninse), another widely dispersed group, but most 

 abundantly distributed over the Arctic and Temperate portions of the Northern 

 hemisphere especially during summer. Some of the genera as well as not a few 

 species appear to have a northern and southern dispersal from an equatorial 

 focus, notably in Totanus, Actiturus and Limosa. Some of the genera are 

 strictly geographical — Machetes is confined to the Old World, Bartramia as 

 exclusively to the New World. Our last subfamily contains the Cleft-footed 

 Sandpipers and Snipes (Scolopacinae) . These are birds of almost cosmopolitan 

 distribution, but, as in the preceding subfamily, they are to a great extent 

 dominant in the Arctic regions during summer. We also find some of the genera 

 with a Primogsean focus (as for instance Tringa, Calidris, and Scolopax). Of the 

 British genera, Gallinago and Scolopax are the two most thoroughly cosmopolitan. 

 The last order with which we have to deal is the Anseriformes, which 

 includes the somewhat heterogeneous assemblage of Screamers, Flamingoes, 

 Swans, Geese, Ducks and Mergansers. Of the three suborders, two are not 

 represented in the present volimie, but the third, the Ducks (Anseres) , is rich in 

 British species. The non-British suborders may be briefly dismissed. The 

 Screamers (Palamedese) are exclusively a New World group, confined to the 

 Neotropical region ; whilst the Flamingoes (Phoenicopteri) are much more cosmo- 

 politan, and occupy the tropical areas of Asia (with South Europe), Africa, and 

 America, but are not represented in Australia. The Anseres are all contained in 

 a single family (Anatida), divisible into some eleven subfamilies, of which no less 

 than five find British representatives. The Ducks and their allies are absolutely 

 cosmopolitan in their distribution — a fact which may be largely due to their 

 exceptional facilities for dispersal. Reviewing the British subfamilies in their 

 order of sequence, we have first to consider the Swans (Cygninse). The distribu- 

 tion of these birds is somewhat remarkable owing to its being discontinuous. 

 Swans are distributed over the Arctic and Temperate portion of the Northern 

 hemisphere and the Temperate portion of the Southern hemisphere — a fact 

 which seems to suggest a dispersal from the Primogsean realm, north and 

 south, at a sufficiently remote era to have produced generic differences in 

 Australia, the most isolated area. Next in succession we have the Geese 

 (Anserinse). Of these, the three British genera are exclusively confiaed to 

 the Northern hemisphere, Chen and Branta being chiefly Arctic in distribution. 

 The typical Geese are northern birds, no species being found south of the 

 equator. Our next subfamily contains the Sheldrakes and Non-diving Ducks 

 (Anatinse). These may fairly be described as cosmopolites, but many of the 

 genera are significantly geographical. Thus Dendrocygna (non-British) is 

 Tropical, and is found right round the world ; Chenalopex ranges over Africa 

 and South America ; Tadorna and Casarca (Sheldrakes) are Old World ; 



