428 C. J. Suuclevall on the Winys of Birds. 



is only an inconsiderable shallow depression in tbe place of 

 this latter, and that between the two wing-bones is broad 

 but not deep. In Picus the two pits are formed as in the 

 Song-birds, but somewhat shorter. Hirundo has them both 

 longest and deepest of all birds known to me. 



As this difference in the exterior is manifestly founded 

 upon a different arrangement of the parts situated under the 

 skin, it seemed natural to make a new investigation of the 

 muscles ; and although this has not been successful in fur- 

 nishing the grounds of an explanation of the differences in 

 the wing-feathers of the Song-birds and the other orders, what 

 has been ascertained may nevertheless be briefly recorded. 



The muscles of the wing have already been described by 

 several authors, but best, and with a comparison of all orders, 

 by Schopss in Meckel's ' Archiv,' 1829. This remarkable 

 memoir ascribes to the whole wing forty-eight muscles, of 

 which I propose to mention only a small part, namely, the 

 muscles of the cubitus, and, supplementarily, those of the 

 humerus. I pass over the muscles of the liand, as also those 

 of the shoulder; and with regard to the latter I will merely 

 remind the reader of the corrections recently made by Retzius 

 (Skand. Naturf. Sallsk. Forhandl. 1842) upon the older 

 descriptions of them. 



Under the skin the whole of the forearm is, as usual, 

 clothed with a thin aponeurosis [fascia cubiti), which gives 

 off sheaths between the muscles, sinew-sheaths, &c. In 

 birds it also forms a peculiar independent band [fascia 

 ulnaris), which commences right upon the convexity of the 

 humeri condylus iyiternus, and finishes with one end upon the os 

 pisiforme, and with the other in the ligamentum carpi. This 

 band therefore lies along the ulna, but separated from it by 

 a considerable sj)ace, wliich is occupied by the flexor 

 muscles. Only in the lowest Water-birds [Pygopodes) it 

 lies close upon the ulna, united to the bone like a direct 

 continuation of the periosteum. It always passes straight 

 forward, strongly strained between its points of attachment. 

 This baud plays a principal part in our exposition, and I 



