42 
POPULAE HISTORY OF BIRDS. 
the secondary quills are very short, and the primaries gradu- 
ally and rapidly elongated, and furnished with very strong 
but highly elastic shafts. The tail, although not so long, is 
similarly constructed, being deeply forked, and so in a man- 
ner divided into two pointed and elongated laminse, similar 
in some degree to the wings, and aiding their action in exe- 
cuting turns. In seizing its prey, while gliding or fluttering 
in the air, the bird would be incommoded by any length of 
neck ; that part therefore is extremely abbreviated, so that 
the head seems as if stuck upon the shoulders, as is the case 
for a similar reason in the Cetacea and fishes. A long pointed 
bill would be of use only to a bird that has objects to pick 
from the ground or any other surface, or from among soil or 
foliage. In the present case, the bird, carried with rapidity 
to its tiny prey, merely requires to open its mouth, which is 
extremely enlarged, and supplied with an abundant viscid 
secretion, which immediately entangles the fly that has been 
caught, and prevents its escape should the mouth be opened 
the next instant. A bird so living has no need of walking, 
and there being nothing superfluous in nature, its feet are 
reduced to cramping organs, by which it can cling to any 
kind of surface when entering its nest, and its gait is merely 
a hobbling motion, aided by the wings. It cannot rise from 
