9 6 ELEMENTS OF ORNITHOLOGY. 
represents a group of Swallows and Martins which is spread 
over the whole world, and contains about eighty-two species. 
Of these the Common Swallow (Hirundo rustica) may answer 
as our example. 
Swifts greatly resemble Swallows in generai appearance and 
in their mode of flight, though this is much more power- 
ful. Nevertheless, as we shall see, they are really very distinct 
from them. They number about eighty-six different kinds, 
which range through the warm and temperate regions of the 
Fig. 100. 


ASS BN 
ty WS 

The Common Roller (Coracias garrula). 
globe. The Common Swift (Cypselus apus) stays with us little 
more than three months, quitting our shores for the South 
about the middle of August. 
Extremely contrasted with the Swift is that charming little, 
bush-loying Bird the Wren (Anorthura troglodytes, tig. 102), the 
lively shrill note of which may be heard all the year round. It 
is an example of a numerous group of small, similar Birds num- 
bering some hundred and thirty-four species, the great majority 
of which are exclusively American. The Golden-crested Wren 
