EXTERNAL ANATOMY OP THE COLEOPTEliA. 
31 
tional eyes, small, and not composed of facets, on tlie 
back of the head ; these are especially noticeable in 
Eomalium, a genus of the Brachelytra. The antennae 
are long flexible instruments, through which the insect 
certainly receives a considerable amount of sensation, 
either by actual contact or atmospheric influence. 
They are nearly always composed of eleven joints, 
though some of them are often indistinct, being clubbed 
together, and in a few species the absolute number varies 
in the sexes ; for instance, in the male of Ischnomera 
melanura there are twelve joints, though the normal 
number is found in the female. They are inserted into a 
cup-like socket in the head, and have often the first or 
basal joint long, and the second short ; but their 
variations in structure are too numerous to be specified 
here. 
Fig. 4 shows the 
under side of the 
head ; a , />, and c 
forming the labium 
or lower lip, where- 
of a is the mentum 
or chin, b the ligula 
or tongue, and c c 
the labial palpi or 
lip feelers ; d d are 
the maxilla) or 
lower jaws (which 
are dissected out. 
Fig- 4- are dissected out. 
composed of the following pieces :—<l\ the galea or 
palpiform lobe; d", the maxillary palpus or jaw feeler ; 
