216 BRITISH BIRDS. 



(75mm.) The tail is ample and much rounded, and 

 the two lateral rectrices shorter than the rest, can be 

 seen, even in flight. These are sometimes still not quite 

 fully grown on the 8Qth day, when the third primary 

 is lost. 



Differences between the First and Second Moults. 

 hi the first moult : — 



1. The primaries are moulted from within outwards, 



from the tenth to the third. 



2. The first two primaries are not moulted. 



3. The secondaries moult in two groups simultaneously 



a. The external (1 and 2) from within outwards. 

 h. The internal (3-15) from without inwards. 



4. All the contour feathers and the tail are moulted. 

 The bird therefore breeds in its first spring in a 



compound plumage. 

 The second moult begins as soon as the chicks are 

 hatched, and in it 



1. The primaries are moulted from within outwards, 

 from the tenth to the first. 



2. The secondaries are moulted in three groups 

 simultaneously. 



a. The external (1 and 2) from within outwards. 



h. The middle (3-11). l' •., ^ . 



c. The internal (12-15)1 ^^^^^ ^^^^^^^^ mwards. 

 Dr. Bureau points out that the time lost in the replace- 

 ment of ten primaries at the second moult in contrast 

 to eight at the first, is compensated for by the shortening 

 of the moult of the secondaries, which moult in three 

 places at once instead of tAvo. 



Determination of Sex. 

 In connexion with the determination of sex by the 

 plumage in adult birds. Dr. Bureau has a good deal to 

 say, and it is clear that this part of his subject is 

 greatly complicated by the amount of individual varia- 

 tion that is found in both sexes. After enumerating 

 a number of characters by which typical males and 

 females can be separated, none of which are, however, 

 invariably found in all specimens, he points out that 

 there are only three that are so constant as to be relied 

 upon with any certainty. Of these, the best of all is 



