138 BRITISH BIRDS. [vol. vn. 



Adult Winter- and Summer-plumages. — ^Acquired in 

 exactly the same way and at the same times as the 

 second-winter and second-summer plumages, and are 

 indistinguishable from them. 



N.B. — I can detect no difference in the plumage of 

 males and females, but all the measurements of the 

 males are larger, including the bare patches of the face. 

 Thus— 



EXPLANATION OF PLATES. 



Plate 4. — Rooks' heads. — Fig. 1, Juvenile {^ June 6th, 1912). Fig. 2, 

 Moulting from Juvenile to First winter ($ Aug. 28th, 1912). 

 Fig. 3, First winter {^ Sept. 9th, 1912). Figs. 4-7, A progressive 

 series of First-summer birds to show the moult of the chin. 

 Degenerate feathers and "aborted pins" are growing on 4-6, 

 while in 7 the moult is nearly complete, but a considerable 

 amount of " down " remains. {Fig. 4, $ March 17th, 1913 ; 

 Fig. 5, S Jan. 30th, 1913 ; Fig. 6, ^ March 17th, 1913 ; Fig. 7, 

 ^ April 24th, 1913.) Figs. 8-13, A progressive series of adults 

 from the Autumn-moult to late summer. Fig 8, In full 

 moult in autumn (? Sept. 9th, 1912.) Fig. 9, The moult nearly 

 complete, showing growth of degenerate feathers and plumules 

 {^ Sept. 14th, 1912.) Figs. 10-13 show the gradual wearing 

 off of these. {Fig. 10, S Dec 31st, 1912; Fig. 11, $ Jan. 30th, 

 1913 ; Fig. 12, $ Dec. 18th, 1912 ; Fig. 13, ? June 5th, 1912). 



Plate 5. — Fig. 14, First-summer Rook — the same bird as in Plate 4, 

 Fig. 5 — to show moult on side of lower mandible. Fig. 15, 

 First-summer Rook — the same bird as in Plate 4, Fig. 7 — to 

 show moult of nasal and forehead bristles. Fig. 16, Adult 

 Eastern Rook {G. f. pastinator) ($ Feb. 27th, 1912, Hankow, 

 China), to show feathered chin. 



Plate 6. — Fig. 17, Photo-micrograph of feather from chin (22 mm. 

 from angle of mandibles) of Juvenile Rook {^ July 16th, 1912), 

 magnified 7 diam. Fig. 18, Feather of First-winter Rook 

 ((J Sept. 9th, 1912) from the same region, magnified the same. 



