170 
ON THE 0LAS3JF10ATI0N OF BIBHS. 
within their reach ; while in one or two of the hang- 
nests [Icterino!) it is used, probably, as a recreation, since 
these birds feed only upon fruit and insects. One of 
the Brazilian water-chats {Fluxncola) is also stated to 
possess the same faculty. But setting these, and a few 
other isolated exceptions aside, we shall find that, out of 
twenty-five families of birds composing the order of the 
perchers, five only may he said to enjoy the faculty of 
melodious singing to any great extent ; three of these 
are in the tribe of Dentirostren, and consist of the 
thrushes (Merulidce), warblers (Si/lviadcB), and such 
part of the chatterers (Ampelida;') as compose the 
genera Vireo and PachycKphala. The remaining two 
are the finches {Fringilliike), and the starling {Stur- 
nidax), in the adjacent circle of the conirostral tribe 
(^Conirostres), Both series, however, are conterminous, 
for they follow each other without the intervention 
of any other family ; thus showing, that however par- 
tially nature has distributed this gift, she has acted with 
all the regularity of system in its allotment. The in- 
stances just before cited of the swallow and the WTen, 
neither of which birds are within the limits alluded to, 
does not invalidate the general force of this rule, but 
must be rather looked upon, like that of the musical 
falcon, as resemblances of analogy, rather than as 
marked deviations from a general law. 
(14.5.) Of the remaining families of perching birds 
it may be more correctly said that their voice is re- 
stricted to the use of language, or in other words, is 
employed only to express their wants or their desires. 
The crow does not sing, but every field naturalist must 
have remarked how much its caws are varied when the 
bird is engaged in different occupations : this is par- 
ticularly observable during their flight, when two or 
three companies meet in the air, and when the whole are 
obviously reconnoitering the fields below them, and 
consulting where they should next alight. To the 
ordinary pedestrian, all these curious, if not interesting, 
traits are lost ; but we know not a more agreeable rest. 
