446 C. J. Sundevall on the Wings of Birds. 
The biceps is wanting, but the brachialis internus passes 
higher up. 
The deltoideus is very small. 
The tensor plicae cutanece 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 } Garruli , 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 
PerdiXj 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 
