TETRAONID^E. 



353 



Spring plumage. — A male, killed in May, lat. 65|° N. Head and neck deep orange- 

 brown, changing towards the shoulders to dusky chestnut ; each feather on the crown and 

 nape crossed by a subterminal bar of pitch-black, and on the base of the neck many zig-zag 

 lines of the same : the scapulars, tertiaries, tail coverts, and several short, scattered feathers 

 on the back and rump, coloured like the base of the neck. Nostril feathers, circumference 

 of the bill, and the eyelids, with the rest of the plumage of the body, white. Fourteen 

 black tail feathers ; the central incumbent pair white. Superciliary comb larger and more 

 conspicuously fringed than in winter. 



Summer plumage. — A male, killed in July, lat. 56°, on the Rocky Mountains. Back, 

 rump, shorter tail coverts, scapulars, tertiaries, and two lower rows of wing coverts, barred 

 alternately with pitch-black and yellowish-brown. Sides of the breast, flanks, and part of 

 the under tail coverts, orange-brown, barred with black. Rest of the plumage as in spring. 

 The white tips of the tail nearly worn off, and the toes entirely naked beneath and partially 

 so above. — A specimen, killed a fortnight later, differed merely in having recently moulted 

 its tail feathers ; the fourteen black ones of different lengths were rather broadly tipped with 

 white ; the central incumbent pair young, but growing up white : all the tail coverts coloured. 



In the female the ground colour of the upper plumage is pitch-black, which is barred with 

 ferruginous, the black bars being broader than in the male. — Towards the end of autumn the 

 Willow Grouse resume their winter livery, the change commencing on the body and finishing 

 on the neck. This second change is not by a reproduction of feathers, but by the coloured 

 ones becoming white, the process commencing on their tips. The alteration takes place in 

 scattered feathers, which at the same time lengthen ; and in a week or ten days the change 

 is complete. Spotted specimens undergoing this change may be distinguished from spring 

 ones at once, by the worn state of the tarsal feathers. 



Length, total 

 ,, of tail 

 „ of wing 

 ,, of bill above 



Inch. Lin. 



16 6 



5 3 



. 7 9 



8 



Dimensions 

 Of the male in winter. 



Length of bill to rictus 

 „ of tarsus 

 ,, of middle toe 

 „ of its nail 



Inch. Lin. 



10i 

 5 

 2 



Length of hind toe 

 ,, of hind nail 



Inch. Lin. 



Weight, about \\\h. 



— R. 



Male. 



2 Z 



