INSECTA. 803 
never more than one kind of eyes; but many of the other orders, besides 
their compound eyes in facets, possess minute smcoth ones (ocelli) in the 
form of brilliant points, sometimes to the number of two, generally three, 
disposed in a triangular form, on the top of the head. These organs are 
always immoveable. The mouth is composed of six principal pieces, of 
which four are ]1teral, disposed in pairs, and moving transversely ; two other 
parts, opposed to one another, and filling up the space between these, being 
placed, the one above the upper pair, and the other under the lower 
In insects which feed on solid substances, the four lateral pieces are con- 
sidered as jaws, and the other two pieces as lips. The two upper jaws, 
generally horny, or scaly, similar to strong teeth, and without an articulated 
appendage, have been distinguished by Fabricius under the name of mandi- 
bles, (mandibule,) the two lower only preserving the name of jaws, (mazille). 
On the back of these are one or two jointed filarnents, called antennule, but 
oftener palpi —a character which distinguishes them from the mandibles. 
They are generally narrow, elongated, compressed, horny or scaly, till near 
the origin of the palpi, with the upper extremity membranous or coriaceous, 
in the form of a reversed triangle, ciliated or hairy, and accompanied often 
on the internal side, by a smaller piece, named the internal lobe or division. 
The part or lobe forming the upper extremity of the jaw, sometimes appears 
in the form of a small palpus, of two joints, which is termed the internal 
maxillary palpus; in others it forms a vesicular, naked, vaulted appendage, , 
called by Fabricius, from its form, galea. In both these cases, the extremity 
of the jaw, or the portion covered by the internal palpus or galea, is always 
horny, pointed, in the form of a hook or tooth, or armed with dentations or 
spines. These insects are always carnivorous or gnawers. When the jaws 
have neither internal palpus, or galea, are entirely horny, and armed with 
teeth, the insects may be considered as very voracious. The number of the 
exterior maxillary palpi varies from two to six. The two pieces opposite 
to these lateral parts have been termed lips; the upper one being generally 
termed labrum (labium superius). The under one, termed the labiwm, or 
labium inferwus, is formed of two parts; one inferior, generally horny or 
coriaceous, is the chin, (mentum,) the other membranous, sometimes entire, 
sometimes notched, or trifid, and bearmg the palpi, is termed ligula. These 
palpi have from two to four joints, and are called labial. They are general- 
ly shorter than the exterior maxillary palpi. The pharynz is situate between 
the jaws and the lip. The interior of the mouth in the Orthoptera, and 
some other insects, has a fleshy caruncle in the form of a tongue, or epiglot- 
tzs. In the Hymenoptera, the pharynx is formed by a triangular process, 
named epipharynx or epiglossus, by Savigny. In this order, also, the jaws 
form small, compressed valves, and the chin becomes a kind of cylindrical 
or conical tube. 
All these parts, as well as the labium, are often much elongated, and com 
pose together a species of trunk or proboscis, which Illiger names premusets, 
