pair of biting jaws (mandibles, ok) (3) a pair of grasping jaws (maxillæ, A, B), and (4) a lower lip (labium, m, a, b). The grasping jaws bear two pairs of jointed jaw fingers (maxillary palpi, D, C), and the lower lip bears a pair of similar lip fingers (labial palpi, d). The biting jaws move sideways; they usually have several pointed notches which serve as teeth. Why should the grasping jaws be beneath the chewing jaws? Why is it better for the lower lip to have fingers than the upper lip? Why are the fingers (or palpi) jointed? (Watch a grasshopper or beetle eating.) Why does an insect need grasping jaws?
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Fig. 123.—Mouth Parts of Beetle.
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Fig. 124.—External Parts of a Beetle.
The chest, or thorax, consists of three rings (Fig. 124) called the front thorax (prothorax), middle thorax (mesothorax) and hind thorax (metathorax), or first, second, and third rings. The first ring bears the first pair of legs, the second ring bears the second pair of legs and the upper or front wings, and the third ring bears the third pair of legs and the under or hind wings.
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Fig. 125.—Leg of Insect.
The six feet of insects are characteristic of them, since no other animals have that number, the spider having eight, the crawfish and crabs having ten, the centipedes still more, while the birds and beasts have less than six. Hence the insects
