24 



Tentorium. — The invaginations for the anterior arms of the ten- 

 torium are very distinct and are either small pores or slit-like openings. 

 They are associated with the lateral margins of the clypeus and are 

 distinct in most pupae (Figs, i, 14, 19, 30; at). 



Labrum. — The labrum is usually distinct along its lateral and dis- 

 tal margins, but seldom separated from the clypeus by a distinct su- 

 ture. Like the clypeus it usually bears setae which are especially con- 

 spicuous in the Eriocraniidae (Figs, i and 2, lb). A peculiar de- 

 velopment occurs in the Heliozelidae and some other families where 

 the labrum extends caudad over the appendages (Fig. 50). 



Pilifers. — This term is applied to the caudo-lateral projections of 

 the labrum, which are so well developed in many Lepidoptera. They 

 are very large in certain superfamilies, notably the Pyralidoidea and 

 the Papilionoidea, and their presence is easily detected by the lobes 

 which are adjacent to the caudo-lateral angles of the labrum and often 

 approximate, or meet on the meson caudad of it, or are separated by 

 a narrow piece of the labial palpi (Figs. 70, 72, 74, 76, 78, 79; pf). 

 The mandibles figured by Scudder ('89, Vol. 3, PI. 87, Fig. 25) are 

 the pilifers. There are often well-developed pilifers present, how- 

 ever, when there are no external indications of their presence. 



Mandibles. — The mandibles are always located adjacent to the 

 caudo-lateral angles of the labrum. They are not functional except 

 in the Micropterygoidea. In this superfamily, as shown in a pupa 

 of the Eriocraniidae (Fig. i, md), the mandibles are very large and 

 used by the pupa to cut its way out of its cocoon and in working its 

 way to the surface of the ground. In the Hepialidae (Fig. 8, md) 

 and in some other families (Fig. 11, md) the mandibular area is def- 

 initely bounded. In still other families the area is distinctly elevated 

 and usually rugose, as in the Eucleidae and Aegeriidae (Figs. 19 and 

 36, md). This type of mandibular area is observed in many of the 

 Sphingidae. In the majority of pupae, however, the mandibles are 

 represented by a smooth area situated in the position indicated above. 

 Bye-pieces. — These are situated laterad of the genae and mesad of 

 the antennae. There are always two regions to be noted : a smooth 

 mesal portion, sometimes only a narrow band but often a wider lunate 

 piece, called the glazed eye-piece; and the larger lateral portion, the 

 sculptured eye-piece. The latter is so called bcause it is always sculp- 

 tured like the adjacent parts of the thorax. The sculpturing on the 

 head is seldom like that found on the thorax and abdomen, but, 

 strange to say, that on the sculptured eye-piece is always like that on 

 the thorax, although the eye-piece is probably an extension of the ver- 

 tex. On the dehiscence of most generalized pupae the eye-pieces are 



