254 THE ZOOLOGIST. 



before it has lost all its structurally youthful characters, the bill 

 of the nestling bird not having been perfectly modified into the 

 long slender form of the fully matured male. 



I have written so many short articles upon the sexing of birds 

 by external characters, that I feel it would be superfluous to go 

 again over the whole ground. I will therefore confine myself to 

 a few general suggestions, which may be useful as guides to the 

 student of this subject. There maybe exceptions to the general 

 rules, because my studies have necessarily been confined to a 

 comparatively small number of species ; and, moreover, there are 

 still many families of birds which I have not examined ; so that, 

 even if my distinctions should prove constant to all members of 

 a family, much yet remains to be done. 



So far as I have had an opportunity of testing sexual charac- 

 ters, I believe that among flying birds, in which the male is 

 dominant, the primaries of the male are longer than those of the 

 female, or, at any rate, the wing from its base to the end of the 

 longest primary shows greater length. 



In the Thrushes (Turdidce), I believe it will be found to be 

 the rule that the entire body is longer in the male, the skull and 

 bill longer and narrower. In the Liotriges the adult males are 

 rather larger than the females, with their bills slightly, but very 

 slightly, broader. In the Bulbuls the same differences occur, 

 but they are more pronounced. In the Tanagers I believe the 

 culmen of the upper mandible in adult cock birds is generally 

 more arched, but the difference is not very marked, and young 

 males in full colour show it less clearly than old birds. How- 

 ever, the sexes of Tanagers generally differ somewhat in colour, 

 even the Superb Tanager (Calliste fastuosa) not being difficult to 

 sex when fully adult. The sexes of Finches differ as regards the 

 form of their beaks according to their habits, so that no general 

 rule can be laid down for them ; the males are usually larger than 

 the females, and have longer wings. The Crows (Corvidce) have 

 broader and stronger bills in the males than in the females. The 

 so-called Piping Crows (Gymnorhina) have longer and more 

 slender bills in the males. The males of Larks are broader in 

 chest, are altogether larger, and have longer wings than the 

 females. The Parrots (according to the late Mr. Abrahams) 

 have a much more rounded blunter infero-posterior angle to the 



