INSECTS. 249 
antenne. Their relative size is very different. Sometimes as in 
Locuste, they exceed the length of the body, in others again they 
are very short and almost concealed beneath the eyes. The form 
likewise is different: the antenne are said to be filiform when they 
are thin and of the same thickness throughout: clavate when they 
have a knob at the end formed of thicker joints, as in butterflies 
(Papiliones), &e. 
The eyes (ocul’) are either simple or compound. The simple 
eyes are named eye-points (ocell’, stemmata): they look like smooth 
shining points placed usually. in a triangle behind the larger eyes ; 
they are seen in Bees, Wasps, &c. The larger eyes are composed 
of numerous six-sided facettes, and are occasionally of such magni- 
tude (as in Diptera, Libellule), as to meet, the head seeming to 
consist almost entirely of these two eyes. In some instances the 
number of facettes is surprisingly great: LEEUWENHOECK counted 
8000 in the eye of a fly, STRAUS nearly 8820 in that of a cockchafer}, 
The oral apparatus (organa ctbaria, Trophi) consist of six 
principal parts, of which four are in pairs and move transversely, 
whilst two face each other above and below. Of these last the 
uppermost is the upper lip (labrum): it is horny and fixed by a 
joint transversely to the most anterior part of the head. The part 
of the head to which the upper lip is fastened is named head-shield 
(clypeus, in French chaperon). The undermost part, facing the other, 
is named the under lip (labéwm): it closes the mouth below: is 
composed of two parts of which the inferior and more rigid is named 
chin (mentum), and the superior, generally membraneous, tongue 
(ligula). Sometimes the ligula has two lateral lobes (paraglosse). 
The remaining four parts are known as upper and under jaws. The 
upper jaws (mandibule) are two, placed immediately beneath the 
upper lip: they move transversely from within outwards, and are 
often very hard. The wnder jaws (maxilla) are ordinarily softer: 
are placed beneath the mandibles, and also move laterally, but are 
less serviceable for cutting the food small than for holding it in the 
mouth and conveying it to the gullet to be swallowed. In the 
Orthoptera there is a membraneous valve which is fastened to the 
maxilla. It is called the helmet (galea) of the lower jaw. 
In addition to these principal parts there are also feelers (palpi, 
1 See plate xx. of SWAMMERDAM’S Bijbel der natuur, where the simple and com- 
pound eyes of a bee are figured. 
