C. J. Sundevall on the Wings of Birds. 411 



with the insertion of the tail [Columba, Coracias, Cajni- 

 midgus, most Psittaci, Picus viridis, lynx), rarely a little 

 shorter [Alcedo, Platycercus, and some other Australian 

 Psittaci), but often \ longer {Cucuhis, Pici varii et nigri) ; 

 they are much shorter (|) only in Trocliilus and Cypselus, 

 which, in all respects, have these feathers so peculiarly 

 formed. 



In the Oscines, as usual, we meet with less variation. 

 In a single form, Cinclus, only have I found the anterior 

 arm-feathers not reaching to the root of the tail ; the}'^ 

 attain only | of the trunk. In Hirundo and Sturnus they 

 extend just to the end of the body, in Turdus and Fringilla 

 usually a little (about | or less) beyond it, in most about \, 

 and in some (e.g. Corvi, Gmruli, Pari) still further (about ^) 

 beyond the end of the body. It would seem as if, in Para- 

 disea apoda, they reach nearly ^ beyond the body {i. e. to 

 nearly twice the length of the body), but I have only seen 

 stuffed specimens of this genus. 



It appears from what has b^en stated above that the 

 length of these feathers, and consequently the breadth of 

 the wing, varies in a great degree according to the generic 

 form to which they belong, but they also vary a little between 

 nearly allied species. A very slight difference in their length, 

 such as can only be expressed by a small number which 

 might be believed to be of no consequence {e.g. j'q of the 

 length, 3-5 millim. in a bird the size of a Sparrow), never- 

 theless produces a considerable increase or diminution in the 

 whole surface of the parachute formed by all the cubital 

 feathers together, which is not only easily recognized by the 

 eye, but may also have an influence upon the power of 

 flight. But leaving out of consideration the variation in the 

 species, it would seem that these feathers are in general 

 longest in the Song-birds, that they gradually diminish 

 throughout the other Orders, and are smallest in the Water- 

 birds. It ought also to be remarked that the length of the 

 cubital feathers is much less subject to variation in young 

 birds than the hand-feathers, which grow forth later. 



We have seen that many weak-flying birds have long arm- 



