Introductiox. ill 



the last pair of legs beneath. There is another small plate above, between the mcso-thorax and 

 the meta-thorax, which is called the saitdlniii (Fig. \,sc). 



The abdomen (Fig. 2, ///) is cylindrical, and consists of nine movable segments ; the first pair 

 of which, and often the last pair also, are united. The segments are arranged in such a 

 manner that the hinder margin of every segment covers the base of the next. Each segment 

 consists of two separate plates, joined at the sides. The last segment contains the anus and 

 the sexual organs (Fig. 5). The male organ is enclosed by two small folds, and the oviduct in 

 the female is sometimes produced into a conspicuous ovipositor. 



The whole body is densely clothed with hair or scales, so that its structure cannot be 

 examined until this covering is removed. There are many other peculiaiities connected with 

 this clothing which we shall notice in their place. 



PECULIARITIES OF THE DIFFERENT PARTS OF THE BODY. 



The Jicad is large or small, and has sometimes a horn-like projection on the forehead. 

 This is cone-shaped, or smooth and truncated, or furnished with either one or three projecting 

 points (Fig. 10), but is generally hidden by the scales. Its covering is hairy or scaly, either 

 raised or flattened, and is sometimes divided by one or several furrows. At other times it 

 forms a pointed and prominent frontal crest above the palpi (Figs. 9 and 13). 



The eyes are prominent, and are either globular (Figs. 14 and 15), or form a rather long 



■ segment of a circle (Fig. 8). They are constructed of many small facets, each of which forms a 



small eye by itself, and this gives the surface a reticulated appearance. The entire surface is 



either covered with short hairs (Fig. 14), or is naked (Fig. 11). In the latter case, the borders 



of the eyes are often furnished with overhanging bristly eyelashes (Fig. 15). 



The antenncE consist of a great number of small joints articulated together. There are gene- 

 rally from forty to sixty, but there are sometimes less than thirty, and in other cases more than 

 a hundred. Their length varies from one-third to three-fourths of the length of the body, but in 

 some cases they are longer or shorter than this. For example, the antennce are scarcely one-sixth 

 of the length of the body in the genus Hepialiis, while in some genera of Tincina the antennae may 

 be six times the length of the whole body. They vary much in shape, and are of great importance 

 in classification. Those which are thread-like, and of equal thickness throughout, are called filiform 

 (Fig. I,/). Those which taper gradually at the end are called setiform (Fig. 2,/). In other species 

 the antennae are gradually thickened towards the end into a club-shape, and are then called clavate 

 (Fig. 16); and in others, again, they thicken suddenly into a knob at the end, which is generally 

 more or less round, and often flattened: these are called capitate antennae (Fig. 17). Those 

 which are thickest near the middle, and taper again towards the end like a spindle, are called 

 fusiform (Fig. 19) ; and their club-shaped extremity is sometimes bent round like a hook (Fig. 18). 

 The separate joints are either cylindrical, or round on one side and flat on the other, or with two 

 or three angles, and the antenna consequently receives a round, half-rounded, or angulated form. 

 The first joint is called the basal joint, and is generally (except in the butterflies and Sphinges) 

 considerably longer and thicker than the succeeding joints. In some genera of Tineina the basal 

 joint is expanded into a scale, which more or less covers the eye when at rest, and is called the 

 eye-cap. The separate joints of the antennae are longer than broad in the butterflies, the Psychida, 

 and in many Micro-Lepidoptera, at least till towards the end of the antennse. In the other groups 

 they are broader than they are long, and often diminish in length towards the extremities. They 

 have many additional peculiarities. They often form short angles at their ends, and widen into 

 conspicuous projections either on one side or on both. The processes on the antenna; can be 



