EXTERNAL anatomy. TONGUE. 4,Q 
upon the eggs and young of which they feed during 
one part of the year, while they live on fruits the rest. 
(53.) The tongue, in the generality of birds, is small, 
thin, and cartilaginous ; the extremity flat and jagged, 
and incapable of being protruded beyond the bill. To this 
however, there are several remarkable exceptions. 'J'hat 
of the ordinary parrots is shaped very much like ours, 
although its substance is not always so fleshy ; and it is 
probable that this is one of the causes which enables 
these birds to imitate so clearly the human voice. Jn 
thetoucan family and motmots {linmphasti(i(e,Prionites), 
this member, without being extensible, is fully as long as 
the bill, very slender, and the sides divided into filaments, 
ao as to resemble, in its general shape, a miniature quill 
leather. There can be no doubt tliat unusual sensibility 
belongs to this form, or it would not have been so elabo- 
rated by the hand of nature. The duck family, however, 
have the largest tongues of all other birds; and by its 
thick fleshy substance, it more resembles that of the 
human subject than even the parrots. When we consider 
the particular use which the duck makes of its tongue, 
we shaD immediately perceive that it is endowed with 
great and unusual sensibility. I'he duck, unlike aU other 
birds, discriminates its food, not by sight or by smeU 
but by the touch of its tongbe. It thrusts its bill in the 
mud, just as a fisherman throws his net into the sea, and 
brings up whatever it contains : from this mouthful of 
stuff It selects, by the tongue alone, what is good for 
rood, and every tiling else is rejected. As the curious 
reader may peruse our former observations on this subject 
m another work* we shaU not in this place enlarge upon 
It. I he smallest tongues are found among the night-jars 
and swallows, — two groups which are at the same time 
Qistinguished by the largest mouths ; but here, again, as in 
tnousand other instances, we may perceive that beautiful 
principle of design which pervades all nature. The 
nabits of the ducks render it essential that the tongue 
JoLnal‘„nho”uSirS No. 
