446 C. J. Suiidevall on the Wings of Birds. 



The biceps is wanting^ but the brachialis internus passes 

 higher up. 



The deltoideus is very small. 



The tensor plica cutanea occurs, although the wing can 

 bend but little. 



Concluding Remarks. 



From what precedes, it appears distinctly that, as regards 

 the external and internal structure of the wing, the Song-birds 

 show a remarkable uniformity. They do the same in all 

 other respects, and it is only necessary to add to the differences 

 from other birds here enumerated, the muscular apparatus of 

 the lower larynx, which is peculiar to them, in order to prove 

 clearly that they constitute a definite and peculiar group in 

 the class of Birds, scarcely containing any transitional forms. 

 That, however, the so-called ^"^ song-muscles^' must be regarded 

 as the expression of a peculiarity in the whole organization, 

 and not merely as a singing-apparatus, is shown distinctly 

 by the fact that they occur in all the species constructed in a 

 certain way, of which a great part do not possess anything 

 that can be called ''song;"" e. g. the Corvi, Garridi, and a 

 number of exotic forms, as also the females which do not sing. 

 Moreover there is a true song in many species which are 

 destitute of the above-mentioned muscles ; for example, in the 

 Diving-ducks, a few Accipitres, the domestic fowl, Coturnix. 

 The " play " of the Tetraones, the cry of Meleagris, the 

 peculiar sounds produced during the breeding-season by 

 Perdix, Scolopax, and many Tringarise, are essentially exactly 

 the same as the song of the small birds. 



It is equally easy to see distinctly that the Water-birds in 

 all respects constitute the most divergent contrast to the 

 Song-birds, and that the Waders and Gallinse are joined with 

 them, these three orders closely agreeing in most parti- 

 culars. 



The Accipitres, indeed, at the first glance, seem to present 

 much difference by reason of their large wings ; but if we 

 accurately compare them, it is found that these wings 

 scarcely differ in any respect from those in a considerable 



