390 



ME. E. DEGEN ON ECDYSIS. 



from Nos. 17-23, neither of these individuals having as yet acquired remiges IV., 

 v., and VI, 



Approximate Tabular Arrangement showing the Development for the Dorsal and the 

 Ventral Series of '' Median Coverts " during four consecutive Perennial Moults. 



Rows. Groups. Sets. 



f Simultaneous Ist 2nd-4th ] st Season. 



SorrLY i 



I Gradual 2nd-4th l8t-2nd 2nd-4th „ 



,. f Anacbronous lst-2nd lst-;3rd l&t-'.'tTA ,, 



Movement i 



I Synchronous 3rd-4th 3rd-4tli 3rd-4tb „ 



^ r Asymmetric lst-2nd 2nd-3rd lst-3rd „ 



Development . . . . i 



I Symmetric 2nd-4tli 4th 4tli „ 



VII. — Summary of the Order in the Perennial Moult of the Wing-feathers. 



The Bemiges. 



Tvro distinctly different principles in the order of the shedding and eventual replace- 

 ment of these feathers are conspicuous. The first is that of the regular sequence 

 of their renewal on the hand-portion from within outwards, though accelerated in 

 certain places or retarded in others, in order to maintain the requisite balance for 

 flight, by a system of approximate symmetry for the whole wing during this critical 

 change. This is the principle which forms the rule for pi-obably the entire Order of 

 the Passeres. 



But it is by no means the expression of the real morphological process of 

 development which takes place, as we shall have an opportunity to prove further on 

 when studying the behaviour of the covert-feathers during the moult. The true 

 morphological principle is probably concealed beneath this purely secondary feature. 

 In less highly organized birds, such as the Picarise, an earlier and more primitive mode, 

 namely, that of starting the moult on the manus from two separate points almost 

 simultaneously, has been observed by Wittmer Stone (44), in the case of the King- 

 fisher, who (on p. 112, I. c), after remarking on the principle of his " Order of Molt," 

 writes thus : — 



" Following these [the two innermost primaries] the primaries are shed at short 

 intervals, one at a time, finishing with the outermost. Excei)tions I have noticed to 

 this order in the Belted Kingfisher ^, Ceryle alcyon, and the Snow-Bunting, Plectro- 

 phenax nivalis"'-^. And further on (p. 113, I. c): — "The Kingfisher is strikingly 



' These italics are mine. 



' Wittmer Stone, on p. 113, also quotes the case of a male Pinmga. 



