Scrape the hairs from the face and examine the horny shell with three fourths inch power. The surface is full of little pits. In the upper part of the face there is a groove, in the middle of which is one of the simple eyes. Just below the antennae sockets is a groove which extends crosswise a short distance on either side and then bends downwards to the mouth. The portion of the face bounded by this groove is called the clypeus. At its lower part is hinged a little oblong piece (labium) which may be moved up and down with a needle. Melt a piece of sealing wax on the centre of a slip of glass (taking care not to break the glass by too sudden heating) and before the wax hardens press the head into it face downwards. Examine with one inch power. The hole near the top of the head shows the position of the neck. The portion of the head around this hole is destitute of hairs and is hollowed in, to make room for the rounded front part of the thorax. Below this one there is another cavity which contains a portion of the mouth parts when they are retracted. At each side of the mouth in front of the base of the sucking organs, are the two jaws (mandibles) each with a little tuft of hair on the outer side. The jaws move freely to and from each other, sideways instead of up and down as do the jaws of the higher animals. The sucking apparatus consists of five pieces viz: two outermost pieces each tapering to a fine point, two, each of which ends in three little joints and one in the centre which projects beyond the others. It may be necessary to spread these out with the needle, to see them well. Separate the thorax from the rest of the body. Scrape off the hairs on the back. Two principal grooves extend across the back, one near the front and one near the hind margin. The thorax is composed of three divisions and these grooves show where they are joined together. The hind division bears the hind wings and the hind pair of legs; the middle division, much the largest division of the three, bears the fore wings and the middle pair of legs; and the foremost division is quite small and bears only the front pair of legs. Remove the wings of one side and examine in a drop of water with one and one half inch power. The wings consist of a shining transparent membrane strengthened by numerous horny veins running through it. Examine with one half inch power. The membrane is seen to be covered with minute hairs and little dots. On the front edge of the hind wing a short distance from the outer end is a row of hooks. At a corresponding place on the hind edge of the fore wing there is a thickening or ridge. When flying, the hooks catch onto the ridge and thus the wings are held together and act as one large wing.