546 PKOCELLAKIID^ 



of reddish-brown, like those of most other Petrels (Saunders, 

 Phil. Trans., clxvii, p. 164). 



Geographical distribution. "Wilson's Petrel has been 

 found breeding on Kerguelen Island, by the Kev. A. E. 

 Eaton ; and examples of birds " were obtained by the 

 'Challenger' Expedition, off the Antarctic ice-barrier on 

 February 14th, 1874 " (Saunders). In summer it is common 

 on some of the islands (notably the Azores) off the West 

 African coast, from whence it can be traced in the South 

 Atlantic down to the Cape, eastward over the Indian 

 Ocean to Australia and New Zealand, and across the 

 South Pacific to Chile and Peru. In the North Atlantic 

 it is common along the American sea-board, visiting the 

 West Indies and Mexico, and reaching about as far north 

 as the latitude of the British Islands. In the Antarctic 

 Ocean the geographical distribution may be said to be cir- 

 cumpolar. 



DESCRIPTIVE CHARACTERS. 



PLUMAGE. Adult male nuptial. General plumage, sooty- 

 black ; forehead, breast, and abdomen, of a paler shade ; 

 greater wing-coverts and inner secondaries, edged with 

 greyish-white ; the primaries and the tail-feathers are more 

 inky black than the rest of the plumage, but the bases of 

 the outer tail-feathers are thinly edged with white ; upper 

 tail-coverts and thigh-patches, white. 



Adult female nuptial. Similar in plumage to the male. 



Adult winter, male and female. Similar to the nuptial 

 plumage. 



Immature, male and female. Resembles the adult 

 plumage. 



BEAK. Black. 



EEET. Black ; proximal portions of the webs, yellow. 



IEIDES. Dark brown. 



AVERAGE MEASUREMENTS. 



TOTAL LENGTH 7 in. 



WING 6'1 ,, 



BEAK 0'7 ,, 



TARSO-META TARSUS 1'5 



EGG 1-3 X 0-9 in. 



Allied Species and 'Representative Forms. 0. gracilis, 

 smaller, with the middle of the abdomen white, inhabits the 

 west coast of South America. 



