226 MOTACILLA YARRELLI. 



different ages, that one might be very apt to consider a speci- 

 men obtained in summer specifically distinct from another pro- 

 cured in winter, or from a young bird. I shall, as usual, 

 describe it first in its perfect or winter plumage. 



Male in Winter. — Although a common, this is a very ele- 

 gant bird, and attracts attention not less by its strongly con- 

 trasted colours thau by its activity and the beauty of its flight. 

 Its bill is rather short, slender, straight, tapering, compressed 

 towards the end, and rather sharp-pointed ; the gape-line nearly 

 straight, the upper outline slightly curved downwards, the 

 lower slightly ascending. Both mandibles are narrow and 

 concave within, with a prominent median line ; the palate flat, 

 with two ridges ; the tongue very slender, five-twelfths long, 

 emarginate and papillate at the base, its tip slit and slightly 

 bristly. The oesophagus is two inches and six-twelfths long, 

 with an average diameter of two-twelfths ; the stomach oblongo- 

 elliptical, compressed ; its length eight-twelfths, its lateral 

 muscles of moderate thickness, the lower thin and inconspicu- 

 ous, the cuticular lining thin, rugous, and of a reddish-brown 

 colour. The intestine is seven and a half inches long, its duo- 

 denal portion two-twelfths in diameter ; the rectum, which is 

 an inch long, dilates to the diameter of half an inch, and the 

 coeca are a twelfth and a half in lensfth. 



The nostrils are elliptical, and about a twelfth in length ; the 

 aperture of the eyes two and a half-twelfths in diameter ; that 

 of the ears three-twelfths. The feet are of moderate length, 



slender ; the tarsus much com- 

 pressed, its scutella indistinct, 

 excepting the lower ; the first 

 toe with eight, the second with 

 nine, the third with thirteen, 

 the fourth with twelve scutella. 

 The claws are of moderate length, extremely compressed, lat- 

 erally grooved, moderately arched, tapering to a fine point, but 

 in old birds usually blunted by being worn ; the hind toe pro- 

 portionally larger. 



The plumage is soft and blended. The wings are rather 



