i°393 X J Allen, Origin and Distribution of N. A. Birds. IO^ 



The Anseres are also a cosmopolitan group, containing many 

 genera of very wide distribution. Particular styles of the Anserine 

 type, however, have been developed over particular regions, as 

 in South America, Australia, and in the Old World tropics. Of 

 the 23 North American genera four only are peculiar to this 

 continent, namely, Lophodytes, Charitonetta, Camptolaimus, 

 and Chen, closely allied respectively to the circumpolar genera 

 Merganser, Glauciotietta, Somateria and Anser, and are thus 

 obviously derived from northern stock. Histrionicus is also 

 almost wholly confined to the northern half of North America, 

 while Arctotietta and Philacte occur only along the arctic 

 coasts of Alaska and Siberia, like several of the genera of ihe 

 Alcidas. Dcndrocygna is tropicopolitan, barely reaching the 

 southern border of the area here under consideration. Anas, 

 Dajila, Spatula, and Erismatura are nearly cosmopolitan. 

 The remaining 14 genera of Ducks, Geese, and Swans are cir- 

 cumpolar, and most of them pass the breeding season in the cold 

 temperate or subarctic regions. Thus of the Anseres only about 

 one sixth of the genera are distinctively North American, and in 

 every case are only slight modifications of circumpolar types, and 

 hence of boreal origin, of probably comparatively recent date. 



The Odontoglossag, or the Flamingoes, are tropical, — a small, 

 structurally widely isolated group, dating at least from the Mio- 

 cene. A single species barely reaches our southern border, 

 though in Pliocene and Post-Pliocene times Flamingoes ranged 

 much farther north than now, both in Europe and North America, 

 and were doubtless more numerous in species, the Flamingoes 

 being a waning group. 



Of the Herodiones, the Spoonbills, the Ibises, and the Storks 

 are for the most part tropical, and hence do not enter prominently 

 into the North American fauna. Ajaja and Guara are tropical 

 American ; Plegadis is subcosmopolitan and slightly more 

 northern ; Tantahis is also essentially tropical American, but has 

 closely related forms in the Old World tropics. Our Herons all 

 belong to nearly cosmopolitan genera and subgenera, many of the 

 species being closely representative of Old World forms of 

 corresponding latitudes. The North American Herodiones thus 

 present no forms distinctively American. 



The PaludicolaB afford us one form, Aramtis, peculiar to 

 America, but it barely reaches our southern border. Of the 



