C. J. Sundevall on the Wings of Birds. 4-23 



cover the next feather with the outer margin. In front of 

 the humerus they sometimes take on another form. 



In the Song-birds there are only two series immediately 

 beneath the margin of the skin, and these are continued 

 without any alteration as far as the base of the humerus. 

 They are unusually soft, with separate hair-like rays, so that 

 they do not present a definite outline (contour). Those in 

 the outer series are small; but those of the inner one are 

 very long and curved, and cover the whole under surface of 

 the arm. In Corvus and Cinclus, however, they are flat and 

 have a more definite form. 



Among the Coccyges, Picus major and P. martins have 

 these feathers nearly as in the Song-birds, but not so long, 

 and of a more definite form ; Picus viridis, like the Psittaci, 

 has three series, none of which has very long feathers. 

 Columba proves to be distinctly divergent ; the fold of 

 skin is clothed with three more widely separated series, of 

 which only one occupies the margin, the second the middle, 

 and the third the inner part of the fold, without any downy 

 series. These feathers are rather short, rounded, and not 

 curved. 



Strix has two series, of which the inner one consists of 

 feathers of moderate length, soft, and but little curved ; near 

 the body they are larger. In Aquila, Buteo, Pernis, Astur, 

 and Falco there are from four to six series below the margin, 

 which occupy a considerable portion of the breadth of the 

 fold, but nevertheless leave room for downy series close to 

 the cubitus. The innermost are of moderate length, the 

 others short ; all are firm, of definite form, and but little 

 curved. 



In Tetrao these feathers perfectly resemble those of the 

 diurnal Birds of Prey. 



Fulica has three series, of which the inner are long and 

 exceedingly soft. In Numenius, Scolopax, and Ciconia there 

 are also three series, but tolerably firm and of definite form 

 — the inner of moderate size, the two outer very small. 



In Anas, Linn., there are only two series of short, 

 ovate, scarcely curved feathers, immediately under the 



2h2 



