INSECTA. 803 



never more than one kind of eyes ; but many of the other orders, besides 

 their compound eyes in facets, possess minute smooth 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 lateral, 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, [mandihula.,) the two lower only preserving the name o{ jaws, (maxilla). 

 On the back of these are one or two jointed filaments, called antennulce, 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 

 spiaes. 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 lahrum (labium superius). The under one, termed the labium, or 

 labium tnferius, 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 bearing 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 pharynx 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- 

 tis. 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 lUiger names promuscis. 



