C. J. Sunclcvall on the Wings of Birds. 405 



The number of cubital feathers depends upon the length of 

 the cubitus upon which they are inserted; and the length of 

 the cubituSj again, is in proportion to the length of the 

 humerus ; we must therefore take these parts into considera- 

 tion. From what has been said, it is clear that all birds 

 which have many cubital feathers also have long wing-bones 

 and, consequently, long wings. We have just spoken of the 

 wings which are long in consequence of the length of the 

 hand-feathers ; these have generally shorter wing-bones. 



The length of the wing-bones can only be determined by 

 comparison with the trunk; and this must be calculated 

 from the shoulder to the last caudal vertebra (the base or 

 insertion of the tail), to which the rectrices are attached. 

 The shoulder is distinguished by the usually projecting end 

 (or process) of the os coracoideum which receives the clavicle 

 {furcula), and which may be distinctly recognized under the 

 skin, immediately in front of the humerus. The articulation 

 of the humerus is situated immediately behind this tubercle, 

 in the anterior part of the trunk itself. The first principle 

 of determination is, therefore, to measure how far the pos- 

 terior wing-fold (the elbow, or the posterior ends of the 

 humerus and cubitus) extends upon the trunk when the 

 wnng is folded up. Of all birds, Diomedea exulans, which has 

 the greatest number of cabital feathers, has also the longest 

 wing-bones ; these reach considerably (by ^g or 32 millim.) 

 beyond the posterior extremity of the trunk. They are 

 shortest in Trochilus and Cypselus, in which they do not 

 reach quite one fourth of the trunk. In general they are 

 longest in Water-birds, Waders, and Raptorial birds. Thus 

 they reach in Diomedea (all species) more or less beyond 

 the base of the tail ; in Pelecanus and Fregata nearly to the 

 extremity of the body (| ?) ; in Carbo rather more than \ (in 

 Dysporus much further) . 



Among the Gavise they reach in Larus to about | ; in 

 Sterna to +f ; in the Procellarise they vary from { (in Tka- 

 lassidroma) to §. 



In Cygnus and Anser they reach § ; but in the Ducks 

 {Anas, Fidigula, Mergus) only a little more than i. 



SER. V. VOL. IV. 2 G 



