ENTOMOLOGY IN OUTLINE STRUCTURE OF INSECTS. 



17 



for masticating the food torn off by the mandibles. These organs are 

 known as the maxillae. To these are usually attached one or two pairs 

 of jointed organs, called palpi, or feelers. One pair of these is attached 

 to the lower jaw or maxilla, and are termed the maxillary palpi, and 

 the others are attached to the lower lip, and are designated the labial 

 palpi. Their office seems to be somewhat like that of the tongue in 



E BCD 



FIG. 14. Various forms of mandibles. A, Melanoplus ; B, Cicindela; C, Apis; 

 D, Onthophagns; E, Chrysopa; F-I, soldier termites. (After Hagen.) 



the higher animals. Third, an upper lip, or labrum, attached to the 

 lower portion of the head; and, fourth, the lower lip, or labium, with 

 its attached palpi. The labium is usually composed of two or more 

 parts, the mentum or chin, which is a broad, horny plate, varying in 

 size in different species, and the ligula, or tongue, which lies on its 

 inner surface. This is usually a membranous or fleshy organ, some- 

 times supported by a horny plate when it 

 projects beyond the mentum. 



Antennas. The antennae are organs found 

 in all insects, and are situated near the com- 

 pound eyes and usually between them. These 

 organs vary greatly in different insects and 

 frequently even in the two sexes of one species. 

 In some cases they are mere knobs, as in the 

 ladybirds; in others they are much longer 

 than the entire insect. They are sometimes 

 feathered; sometimes branched, knobbed, or 

 composed of a series of spherical joints joined 

 together like a string of beads. In some cases 

 they connect by a number of plates, and, 

 throughout the whole class, they vary in 

 structure almost as much as the species them- 

 selves differ one from the other. What the 

 object of these organs is, has not been defin- 

 itely determined. They are commonly called feelers, and certainly 

 appear to possess a tactile sense. They may, in some cases, be organs of 

 hearing, and sometimes seem to have auditory qualities. Experiments 



2-E 



FIG. 15. Head of butterfly 

 (Vanessa), p, labial palpus; 

 a, antennae ; I, proboscis. 



