﻿EXTERNAL ANATOMY. TONGUE. 49 



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. That 

 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. In 

 the toucan family and motmots (Ramphastidce, Priorities) , 

 this member, without being extensible, is fully as long as 

 the bill, very slender, and the sides divided into filaments, 

 so as to resemble, in its general shape, a miniature quill 

 feather. There can be no doubt that 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 shall immediately perceive that it is endowed with 

 great and unusual sensibility. The duck, unlike all other 

 birds, discriminates its food, not by sight or by smell, 

 but by the touch of its tongue. 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 

 food, and every thing else is rejected. As the curious 

 reader may peruse our former observations on this subject 

 in another work *, we shall not in this place enlarge upon 

 it. The smallest tongues are found among the night-jars 

 and swallows, — two groups which are at the same time 

 distinguished by the largest mouths ; but here, again, as in 

 a thousand other instances, we may perceive that beautiful 

 principle of design which pervades all nature. The 

 habits of the ducks render it essential that the tongue 



* On the Typical Perfection of the Family of Anatida?, printed in the 

 Journal of the Royal Institution, No. 4. 



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