412 SYLVIID^E. 



the summer plumages are too trivial to require separate notice. 

 These birds are among the most difficult to identify, and the 

 student will find the points set forth in the key and in the 

 short characters I have given of more service than long elaborate 

 descriptions. 



Key to the Species. 



a. With no band on crown of head. 



a'. Second primary about equal to sixth . . A. borealis, p. 412. 

 b'. Second primary between sixth and 



eighth. 

 a". Upper plumage lively green ; lower 



rather bright yellow A. nitidus, p. 413. 



b". Upper plumage dull green ; lower 

 greyish yellow. 



a". With one wing-bar A. viridanus, p. 414. 



b'". With two wing-bars . A. plumbeitarsus, p. 414. 



c". Upper plumage very dark green ; 



lower greyish yellow A. magnirostris, p. 415. 



d". Upper plumage tinged with ochra- 



ceous; lower with buff A. tenettipes, p. 416. 



c'. Second primary about equal to tenth . . A. lugubris, p. 417. 



b. With a coronal band. 



d'. Inner webs of two outer pairs of tail- 

 feathers brown like remainder of tail. 

 e". Lower plumage whitish, contrasting 

 with bright yellow of under tail- 

 coverts A. coronattis, p. 417. 



f". Lower plumage uniform pale yellow, 

 c"'. Larger ; wing 2 '3 to 2-7 ; tail 



about 2 A. occipitalis, p. 418. 



d'". Smaller; wing 2'1 to 2-3; tail 



about 1-8 A. trochiloides, p. 419. 



e. Inner webs of two outer pairs of tail- 

 feathers entirely white A. davisoni, p. 419. 



420. Acanthopneuste borealis. The Arctic Willow- Warbler. 



Phyllopneuste borealis, Bias. Naum. 1858, p. 313 ; Hume, S. F. iv, 



p. 290. 

 Phylloscopus borealis (Bias.), Hume fy Dan. 8. F. vi, p. 352 ; Hume, 



Cat. no. 556 bis ; Oates, S. F. x, p. 222 ; id. B. B. i, p. 77 ; Seebohm, 



Cat. B. M. v, p. 40 ; Hume, S. F. xi, p. 218. 



Coloration. Upper plumage olive-green, lighter on the rump ; 

 wings brown, the outer webs edged with olive-green ; wing-coverts 

 brown on the inner and olive-green on the outer webs ; the median 

 and greater coverts with yellowish -white tips, forming two bars ; 

 tail brown, the outer webs edged with olive-green ; a broad and 

 well-defined eye-streak, reaching to the nape, yellowish white ; 

 lores brown ; ear-coverts olive, mingled with yellowish ; under 

 plumage white, suffused with yellow ; under wing-coverts and axil- 

 Jaries pale yellow. 



