80 ON THE CLASSIFICATION OP BIRDS. 
in constant exercise or exertion, as in the generality of 
Other birds. Other characters accompany these, no less 
indicative of birds which feed exclusively upon the 
wing : the bill is always considerably depressed or flat- 
tened, particularly at its base ; and the sides of the 
mouth are defended with stiff bristles, to confine the 
struggles of their prey. 
(90.) The geographic range of this family, taken 
collectively, extends to the temperate and tropical lati- 
tudes of the Old and the New World ; although, strictly 
speaking, there are probably no genuine flycatchers in 
North America, where their station would seem to be 
fiUed by the little tyrants {Tyrannula) and the flycatch- 
ing warblers (Sylvicfllina;), both which groups are un- 
known in Africa and India, — the two countries most 
prolific in the typical species of Muscicapa. Having 
already made the natural arrangement of this intricate 
and interesting family the subject of a separate work*, 
which our space in this wiU not enable us again to go 
over, the reader must be satisfied with a rapid survey 
only of the primary divisions. The contents of the 
entire family, together with the singular and beautiful 
analogies presented by the latter groups, even in their 
most minute details, will be found fully illustrated in 
the work alluded to. 
(91.) The primary divisions appear to be represented 
by the following genera : — Eurylmmux, Muxdcnpa, 
Fhmicola, Psaris, and Querula : these constitute, ac- 
cording to our present views, the types of so many 
subfamilies, very unequal, indeed, in their contents, 
yet blending sufliciently into each other to point out 
their circular succession. The two first are clearly the 
typical and the subtypical groups ; the three next are 
aberrant. 
(92.) The Eurylaiminee, or broadbills, are the most 
remarkable birds of the whole family : the species are 
very few, and their geographic limits seem to be restricted 
♦ The Natural History and Arrangement of the Muscicapida;, or Fly. 
catchers. 
