BUCK-BILLED PLATYPUS. 
blance to that of the duck* as to induce a belief 
that it was calculated for exactly the same purposes ; 
yet when all its parts were carefully reviewed, he 
found that it differed in a variety of circumstances. 
This, it appears, is not the animal's mouth ; but is 
merely a projecture beyond, and added to it. 
The cavity of the mouth is similar to that of 
other quadrupeds, and has two grinders on each 
side, both in the upper and under jaw : but instead 
of front-teeth, the nasal and palate bones are con- 
tinued forward, lengthening the interior nostrils, 
and forming the upper part of the beak ; and the 
two portions of the lower jaw, instead of termi- 
nating, as in other quadrupeds, are also continued 
forwards, forming the under portion of the beak. 
This structure differs materially from the bills of 
all birds : since in the feathered tribe the cavities 
of the nostrils do not extend beyond the root of 
the bill ; and in the lower portions, which corres- 
pond with the under jaw of quadrupeds, the edges 
are hard, to answer the purpose of teeth, and in 
the middle there is an hollow space to receive the 
tongue ; but in the platypus, the two thin plates 
of bone are in the centre, and the parts that 
surround them are composed of skin and mem- 
brane, in which, probably, a muscular structure iff 
included. 
The teeth have no fangs that sink into the jaw, as 
in most other quadrupeds. But are embedded in the 
gums. The tongue is scarcely half an inch long, 
and the moveable part is not more than a quarter 
of an inch. It can be drawn entirely into the 
mouth ; and> when extended, reaches about a 
quarter of an inch into the beak. The organ of 
smell differs in some measure from that of both 
quadrupeds and birds. The external opening is 
placed near the end of the beak ; whence are 
snperaddcd to it two cavities, extending all the 
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