ANATOMY OF INSECTS. 



285 



The antenna (Fig. 5), which are attached to the head either in front of or between the eyes, are 

 jointed organs of the most various development; sometimes excessively long, and many-jointed; some- 

 times very short, and composed of but few pieces; sometimes thread-like or necklace-like, and composed of 

 joints of nearly equal thickness throughout, or tapering more or less towards the extremity; sometimes 

 clubbed at the end by the enlargement of a certain number of the terminal joints, or gradually swelling 

 from the base to near the extremity ; sometimes serrated or feathered on one or both sides by the 

 emission of more or less fine processes from the joints, or foliated by the widening of such processes 

 into leaves, which may be more or less separated or pressed together, like the leaves of a book. In 

 many cases, the first joint is longer and more robust than those which follow it ; and sometimes the 

 latter are attached to the first joints at an angle, instead of being continuous with it ; such antennae 



Fig 6. ORGANS OF THE MOUTH. 

 1, Labrum, or Upper Lip ; 2, Mandibles; 3, Maxillae ; 4, Labium, or Lower Lip; 5, Tongue. 



are called kneed, or geniculate, and may be well seen in the common Ants. The differences of the 

 antennae furnish characters of great systematic importance. 



The organs of the mouth (Fig. 6) must now receive our attention. The labrum, or upper lip, has 

 already been mentioned. It is a small plate, usually of horny texture, articulated to the clypeus, but 

 sometimes amalgamated with it, and really belonging to the head, although functionally forming part of 

 the mouth. Immediately behind the labrum, in the mouth of a biting insect, we find a pair of solid 

 horny organs, articulated to the head by a hinge-joint. They are often of considerable size, pointed at 

 the apex, and armed with teeth, rendering them formidable weapons ; at other times, shorter, and 

 adapted rather to the gnawing of vegetable substances ; but in all cases they are simple organs with 

 no jointed appendages of any kind. This first pair of jaws is called the mandibles. 



The jaws of the second pair, or the maxUlcK, are by no means so simple, and in them we may 

 trace some homology with the limbs attached to the thoracic segments. Thus the first joint of these 

 jaws, the hinge-joint (cardo), which is placed transversely to the head, represents the hip-joint (coica), 

 and this is followed by a stem-joint (stipes), attached to it at a right angle, and corresponding to the 

 thigh. On the outside of the latter is a separate piece, known as the scale (sqitama), which bears a 



