26. ocnxiioDROMus. 22o 



toes darker ; iris dark brown " (L. Stejneger). Total length 

 7 - 5 inches, culmen - 75, wing 5 - 2, tail 2*1, tarsus 1*2. 



Adult female in summer plumage. Similar to the male, but less 

 richly coloured, the rufous chest-band never so pronounced, and 

 the facial markings less developed, the black bands on the forehead 

 often obsolete : "bill black; feet dark grey, with an olive tinge; 

 toes darker, blackish; iris dark hazel" (L. Stejneger). Total length 

 7 inches, culmen OS, wing 5 - 5, tail 1'85, tarsus 1*2. 



Adult in winter plumage. Differs from the summer plumage in 

 wanting the facial markings and the rufous chest. Very similar to 

 the winter plumage of 0. geoffroyi, and distinguished chiefly by its 

 smaller size, shorter bill, and shorter tarsus. There is also a 

 little moro brown on the ear-coverts. 



Young. Similar to the adults in winter plumage, but darker 

 brown, all the feathers edged with sandy brown, the eyebrow, sides 

 of face, and under surface of the body with a strong tint of sandy 

 buff: "bill, angle of mouth, and ring round the eyes black; legs 

 clear grey; tarsus tinged with yellowish, toes with blackish, and 

 soles with reddish; iris dark brown" (L. Stejneger). 



The exact method by which the rufous chest of the summer 

 plumage is gained is not easy to discover. In some specimeus in 

 winter dress there is a distinct narrow line of brown across the 

 fore-neck; in most of the series of skins in the Museum this is 

 wanting, as it is also in young birds. It may therefore be a sign of 

 very old birds only, as there are traces of brown feathers in an old 

 bird which has not quite attained its full summer plumage. In 

 the specimen in question it is also evident that the rufous breast is 

 being acquired by a change of colour in the feather, from brown to 

 rufous, as well as by a moult. Probably only very old birds go 

 through this double process, as in the majority of specimens the 

 rufous breast appears to be gained by a moult only. "When first 

 developed all the rufous feathers are edged with white. 



A young bird is described by Dr. Stejneger as somewhat re- 

 sembling the adults. " The brownish grey of the back is paler, and 

 each feather narrowly edged with isabella colour, with which also 

 the lower parts are suffused. On the pectoral region a huffish 

 Sage replaces the rufous collar, and the black markings are absenl 

 from the head, the cheeks and ear-coverts being slightly dusky ; 

 the forehead between the bill and the eyes whitish, suffused with 

 isabella colour." 



The winter plumage and young livery of the western and eastern 

 forms of 0. mongolus are, as might have been expected, very 

 difficult to distinguish, but the western form seems always to have 

 a longer tarsus (about T25 inch), whereas the eastern form has the 

 t irsus about 1*1 inch. 



Hob. Breeds in Eastern Siberia and the Commander Islands, and 

 even extends its range to Alaska. Passes through China on migra- 

 tion to the Philippines and the Moluccas, wintering in these islands 

 and Australia. 



VOL. XXIV. Q 



