6i8 



PATAGONIAN EXPEDITIONS I ZOOLOGY. 



Neck : Throat and back of neck slaty, or grey ; the lower under neck 

 white. 



Back : Interscapular region and lower back clear slate, or slaty grey ; 

 the rump and upper tail-coverts pure white ; some of the feathers of the 

 beginning of the white on the rump tinged with rusty. 



FIG. 308. 



Tachytriorchis albicaudatus. Adult male, cited. Natural size. 



Tail : White, with a broad sub-terminal band of black, and a terminal 

 narrow bar of pure white ; the part of the tail anterior to the sub-terminal 

 band of black has the white crossed by numerous narrow stripes, or lines 

 of slaty grey, or pale slate color. 



Wings : Darker than the back of the same tone and with the anterior 

 lesser coverts rusty, as are often some of the smaller scapulars ; less fre- 

 quently this rusty shade is apparent on the longer scapulars ; under wing- 

 coverts white ; axillaries white, barred with slaty or grey. 



Lower parts : Except the throat, white ; immaculate generally save on 

 the flanks, thighs and under tail-coverts, which usually are faintly barred 

 and marked with rusty, ash-grey, or dusky. Field notes on the colors of 

 the bill, cere, feet and legs, as well as that of the irides, are not available. 



Adult female. Similar to the adult male, but with a greater amount of 

 rusty on the shoulder and the general color usually darker and richer; 

 larger than the adult male; length 23.00; wing 17.80; tail 10.25. 



Immature birds and young of the year. Male; young of the year. 

 General color of the plumage deep dusky brown ; the head darker, the 

 lores white or whitish, and an indistinct white eyebrow ; the feathers of the 



