COLEOPTEEOtTS INSECTS. 
103 
immediately behind it, which may be considered 
as forming its base, is named the chin (mentuni). 
This piece is usually transverse, or broader than 
long, and is in most instances sinuated or notched 
in the middle of its anterior edge, with an acute tooth 
in the centre of the notch, which is sometimes bi- 
fid. From each side of the labium, and frequently 
attached to its lateral margin, there projects an ar- 
ticulated feeler, similar to those borne by the max- 
ill®. These are called the labial palpi. They ge- 
nerally consist of three moveable articulations, at- 
tached to a fourth which is adherent and forms a 
support to the others. They seldom equal the ex- 
ternal maxillary palpi in length, and the terminal 
joint does not exhibit such a variety of form, being 
most commonly somewhat clavate, or nearly of equal 
breadth throughout its whole length. 
The most conspicuous appendages of the head 
are two jointed organs, which stand out like horns 
from the forehead, and are named antenna . These 
never exceed two in number in genuine insects, and 
are situated anterior to and rather beneath the re- 
gion of the eyes : occasionally they are placed close 
to the margin of the eyes, afnd in some instances the 
latter have a sinuosity for their reception, and par- 
tially encompass their base. They are generally 
composed of eleven obconical or tubular joints, lia- 
ble to great variation in their relative proportions. 
Occasionally, however, the joints do not exceed 
