286 MOTACILLIDJE. 



sexes are alike or nearly so, and the difference between the sum- 

 mer and winter plumage in most of the species is very striking. 

 The Pied Wagtails are constantly undergoing a change of colour, 

 and it is hardly possible to find two birds at the same date in 

 the same state of plumage. This causes them to be very difficult 

 to identify by any set description. The Yellow Wagtails do not 

 undergo such complete changes as the Pied, but their similarity 

 to each other is so great in winter and immature plumage, that 

 their recognition is still more difficult. 



The Wagtails have the tail and wing of nearly equal length, and 

 they have the habit of vibrating the former repeatedly. They fre- 

 quent open land, fields, and the banks of rivers and ponds, some 

 of the species of Yellow Wagtails being only found on marshy land. 

 They construct their nests on or near the ground or in holes of 

 walls and banks, and their eggs are much spotted with brown. 



Key to the Species. 



A. Hind claw much curved and shorter than 



hind toe (fig. 78). 

 a'. Plumage black, white, and grey. 



a". Ear-coverts and sides of neck always 

 white-washed. 

 a'". No black streak through eye. 



a % . Greater wing-coverts merely mar- 

 gined with white ; back never 



black M. alba, p. 287. 



bK Outer webs of greater wing-coverts 

 entirely white ; back black or dusky 



on the mantle M. leueopsis, p. 288. 



V". A broad black streak through the eye. M. ocularis, p. 289. 

 b". Ear-coverts and sides of neck always 

 black. 

 c". Forehead entirely white. 



c 4 Back always grey M. personata, p. 290. 



rZ 4 . Back black or with traces of black 



or dusky M. hodgsoni, p. 291. 



d'". Forehead with black of the crown [p. 291. 



produced to base of bill M. maderaspatensis, 



b'. Plumage largely yellow and green M. melanope, p. 293. 



B. Hind claw little curved and much longer than 



hind toe (fig. 81, p. 294). 

 c\ Tarsus unmistakably shorter than one inch. 



c". Crown dark slaty grey; supercilium 



absent or obsolete ; cheeks blackish . . M. boreali*, p. 294. 



d". Crown dark slaty blue; supercilium 

 very broad and distinct ; cheeks black- 

 ish and ear-coverts streaked with white. M.flava, p. 295. 



e". Crown pale grey ; supercilium broad 



and distinct ; cheeks white M. beema, p. 296. 



/". Crown black ; supercilium absent or 

 obsolete ; cheeks and ear-coverts deep 

 black M.feldeggi, p. 297. 



