28 NOTES ON 
quisite to describe it here, for the illustration of 
which I have made two sketches of the different 
parts. 
The mouth is situated on the inferior surface 
of the head, and is concealed from view by a 
peculiar piece of apparatus, denominated by 
naturalists the mask ; it is composed of several 
pieces, and its structure varies in different spe- 
cies: in the present one it consists of two cor- 
neous plates, terminated by a pair of forceps. 
The form of these plates, extended outwards, 
is shewn in the annexed figure, which represents 
a magnified nether-view of the head and thorax, 
and the first two integuments of the abdomen. 
The first piece of this manducatory instru- 
ment is attached to the head, near the protho- 
rax, by a strong joint; this plate, in its natural 
position, is thrown back, and covered by the 
second plate, to which it is attached by a joint; 
it is convex externally, but concave next the 
mouth, whereby the juices of its prey are more 
easily conducted to it. 
In the following view the parts are thrown 
back, to show the mouth and internal structure 
of the plates; the forceps, which terminate the 
second plate, lying upon it, are not very dis- 
tinctly seen. It must be remembered, however, 
