become gradually defined, until one bright day the last evolution is completed, and with a few convulsive movements the perfect insect bursts out of its enveloping swaddling clothes and appears in all its beauty and perfection. Some groups, however, undergo a much more simple or incomplete metamorphosis; emerging from the egg a baby insect ready to eat, (like the grasshopper,) the same food as its mother; it undergoes a series of moults, and after casting its skin every time, becomes more nearly perfect without any true pupal stage, and finally after the last moult comes forth with well-developed wings, a perfect insect. The typical insect is furnished with a large compound eye on either side of the head composed of a number of small sections called facets, varying in number from sixteen to several thousands in some of the more highly developed families, and two or three simple eyes forming bright shining dots between the compound pair called ocelli. In some groups these ocelli are wanting; in others both eyes and ocelli, so the insects are therefore blind. The mouth parts are composed of several hard plates; in chewing or biting (mandibulate) insects, they consist of a pair of stout jaws, in front of which lies the labrum, and behind the maxillae; again behind the maxillae follows a second pair fused together to form the labium. Both labium and maxillae are provided with a pair of slender jointed appendages known as labial and maxillary palpi; these are used as fingers to assist in drawing food into the mouth. In those groups with sucking (haustellate) mouths these various parts are coalesced into a simple sucking tube ending in a sharp style-like tip, which is buried in the tissue of the plant when the insect is feeding. The antennae when well developed consist of a number of distinct rings or segments, standing out on either side of the head, and generally attached to the front of the head between the eyes; they serve as organs of touch, smell, and probably hearing. The legs contain five distinct joints; first, the coxae or hips; next, the trochanters, small joints with a ball and socket-like action from which the femora or thighs move backward and forward; to these are attached the tibiae or shanks terminating in the tarsi or feet at the extremity. Most insects are also furnished with a pair of tarsal claws, between which may be a small pad, called the pulvillus or empodium.