160 BRITISH BIRDS. [vol. vir. 



The Moult of the Tail. 



The juvenile-tail on the 29th day is rounded in outline, 

 very slightly hollowed out centrally, the feathers narrow 

 and about 40 mm. long. It is full-grown bj^ the 35th day, 

 and its extremity forms a wavy line. By the 41st day 

 the middle rectrices have been lost and the tail assumes 

 a characteristic " Swallow-tailed " appearance, which, however, 

 becomes daily less and less evident owing to the growth 

 of the long central upper tail-coverts. By the 49th day 

 only two pairs of lateral rectrices of the juvenile-plumage 

 remain, but the new central ones, now 60 mm. long, project 

 beyond them, and with the new short lateral rectrices, 

 form an outline convex centrally with a concavity on either 

 side. By the 58th day the central rectrices project 10 mm. 

 beyond the upper coverts, but the outline remains much 

 as before. By the 70th day only a single pair of juvenile- 

 rectrices remain, and the whole tail is longer and more rounded. 

 The last pair of juvenile-rectrices are lost about the 80th 

 daj^ and the whole tail is full grown by the 110th day. 



Differences between the First and Second Moults. 



These are exactly as already outlined (Vol. V., p. 216) 

 for the Common Partridge, \^ ith this exception, that in the 

 second moult the middle group of secondaries comprises 

 the third to the ninth in the case of the present species, 

 whereas in the case of the Common Partridge the tenth and 

 eleventh are included in this group also. The scales of the 

 feet are renewed annually in autumn. 



Determination of Sex. 



There are no plumage characters whereby the sexes of 

 the Red-legged Partridge can be distinguished. Males 

 are generally more stoutly built than females, and their 

 weights tend to be heavier, but this is quite undependable. 

 The tarsus of the male is stouter and bears a callosity on 

 its inner surface. This is first visible about the 86th daj^ 

 though discernible by touch sometimes as early as the 70tli. 

 At the age of two years a second nodule appears near the 

 first, and at subsequent times others which eventually 

 coalesce to form a nodular mass. Dr. Bureau does not mention 

 anv case of the growth of this callositv in the female. 



