Tails 405 
shall find many unexpected uses to which the tail is put, 
and yet those which have been explained are a mere frac- 
tion of the problems which still await solution. 
The principal use of the tail-feathers in birds is, of 
course, to perform the function of a rudder, and we find 
that the arrangement of the bones perfectly carries out 
the simile of a tail to the rudder of a ship; namely, a 
broad, expanded surface which is closely hinged to the 
Kia. 820. Fie. 321. 
Tail of Barn Swallow, closed (320) and spread (321). 
body by several movable joints. The real tail of a bird 
is the small, fleshy protuberance which in our roast 
chicken we call the “pope’s nose”; but in common par- 
lance the word tail has come to be applied to the large 
feathers which sprout from this structure. Thus, although 
not comparable to the appendages of mammals, the so- 
called tail of a bird is superficially more like the correspond- 
ing organ of a whale than the tail-fin of a fish, since it is 
expanded horizontally instead of vertically. 
