316 ZOOLOGY. 
_ ing as are the others, by which character the birds of this order may at 
once be distinguished from any of the others, except the Scansorgs, in 
which, however, the arrangement of the toes in pairs is so peculiar that no 
chance of confusion exists. 
The food of the Passeres consists principally of fruits or seeds and 
insects, the greater part of the species being omnivorous, or eating indis- 
criminately almost any description of these two classes of food which can 
be most readily obtained. There are many genera, however, the food of 
which is exclusively insects, and many others which never or rarely eat 
anything else than seeds; and others, again, which subsist almost entirely 
upon the pulp of fruits. All these, however, admit of classification, and 
will be regarded by us as constituting sub-orders or tribes. 
The ian ynx, or organ of voice, is generally of complex structure in the 
birds of this order, which contains all that are commonly known as singing 
birds. There are few species which do not either sing or utter notes more 
or less musical, especially during the season of courtship; and even of those 
whose voices are harsh, some are frequently capable of being taught to 
imitate other sounds. 
In this order the female is very generally smaller and ne brilliant in her 
plumage than the male. They usually live in pairs, build mostly in trees, 
and irequently display great art in the construction of their nests. 
We shall divide this extensive order into four sub-orders or tribes, 
viz.: Fisstrosrres, or split-billed birds, Trnurrostres, or slender-billed, 
Dentirostres, or birds with toothed bills, and Conirosrres, or conic-billed 
birds. 
7 Sus-Orper 1. Fissirostres. 
This is comparatively a small group when compared with the extensive 
sub-orders of Dentirostres and Conirostres. It comprises all the birds com- 
monly known by the names of Swallows, Night-hawks, Kingfishers, Tro- 
gons, Bee-eaters, and some others of similar general characters. 
The Fissirostres are generally distinguished by having the powers of 
flight developed to the highest degree. The beak is usually short, broad, 
and very deeply cleft, so that the opening of the mouth is very wide, or, 
as some of the old writers express it, they are very big in the swallow. 
Possessing this kind of bill they are adapted to capturing insects on the 
wing, receiving them into their mouths while in full flight. There are, 
however, some genera in which the characters of this group are not so 
strongly marked, and in which the bill is longer and stronger and the flight 
not so rapid nor long continued, but they all have the chavactenetne wide 
mouth. 
These birds subsist almost entirely upon winged insects. 
Fam. 1. Hirunprnipa, or Swauitows. Bill small, much depressed, some- 
what triangular; wings mostly very long, curved; tail various, frequently 
long and forked, sometimes short me truncate. Plumage compact, glossy ; 
size small. 
No birds are more universally or more favorably known than the 
swallows. Distributed through the entire globe, and usually conspicuous 
520 
