C. J. Sundevall on the Wings of Birds. 419 



wards, towards the remiges. The inner branch, which in all 

 other feathers is an accessory plume, seems therefore in 

 these to have been fully developed, while the outer branch 

 quite disappears, for it is entirely deficient, and has not even 

 persisted in the form of an accessory plume. These feathers 

 constitute two series (one of which, however, often disap- 

 pears), which may be regarded as corresponding to the first 

 and second series of covert-feathers (or possibly the quill- 

 feathers and greater covert-feathers of the upper surface !). 

 They often retain a rigidity and straightness and an external 

 form which give them some resemblance to quill-feathers. 



On the cubitus the feathers of the first of these two series 

 are firmly attached, and just like the remiges, with the inner 

 (posterior) margin free, covering the outer (anterior) margin 

 of the next feather ; but in the second series they are movable 

 and, more than any other wing-feathers, can be suppressed ; 

 further, they lie with the margins in the opposite direction 

 to the former, so that the outer edge of each feather is free 

 and covers the inner edge of the next one. This is so con- 

 stant that I have never found an exception to it ; and when 

 either of the two series is entirely deficient, we can recognize 

 by the position of the margins which it is that remains. The 

 two series are continued upon the hand, but here they are 

 often interrupted or divergent. In those birds in which the 

 cubital remiges are continued beyond the joint upon the 

 humerus (Gallinse, Raptorial birds. Waders, Water-birds), 

 the second series of reversed feathers is continued in the 

 same way, but not the first (see fig. 4, o, nos. 1 Sc 2). 



In all Song-birds the whole of the first series is so com- 

 pletely deficient that not a trace of it remains. The second 

 series consists usually of small feathers with downy edges, 

 which are concealed by the following ones ; but in Corvus, 

 Garrulus, Troglodytes, and Ciuclus they are larger and firmer ; 

 in Ampelis garrulus and in some Passeres (e. g. Pyrrhula) 

 they are concealed everywhere except upon the middle part of 

 the hand, where they project beyond the following feathers. 



In all the other orders, on the contrary, the first row ap- 

 pears always to occur ; and if either of them is wanting or 



