330 BRITISH LEPIDOPTERA. 



without armature, strongly impressed ventral grooves on 8 and 10. 

 Face-parts very much as in the $ , except that cheeks project far down- 

 ward laterally, like those of an exaggerated $ M. crassiorella, but larger 

 and more pointed outwardly, and the maxillae more pointed andappressed 

 to labium, as in P. betulina $ , very nearly as long as labium, division 

 between labium and maxilla? to base, and nearly longitudinal in direc- 

 tion, making labium of equal width throughout ; sides of labrum not 

 incurved at top as in $ ; legs and antennae very short (compared 

 with those of $ ), hindwings very distinct at posterior margin of fore- 

 wings. 



Dehiscence of female pupa of F. casta. — The mesothorax splits 

 dorsally, and separates from the metathorax, but remains firmly 

 attached to the wing-cases and assumes a sloping position, its dorsal 

 end being just outside the sack, its other extremity firmly fixed to the 

 wings. These pieces, therefore, one on each side (or rather more 

 dorsally), are all of the exposed pupal parts that occupy the narrow 

 neck of the sack, and, by their elasticity, taking a firm basis by their 

 attachment to the wings, maintain the opening. Outside the sack the 

 prothoracic piece is attached to the anterior margin of the dorsal end 

 of the mesothoracic piece in such a way that it lies along the edge of 

 the opening of the sack, its inner surface sloping outwards so as to 

 make the opening funnel-shaped where it is, and form the dorsal portion 

 of the outer member of what I have compared (vide, post. p. 332) with a 

 rivet. It carries at its anterior margin the dorsal head-piece, which has 

 no other function than to slightly extend the slopes of the funnel. Bound 

 the rest of the opening of the sack, i.e., opposite the venter of the 

 pupa, extend from the ventral ends of the prothoracic pieces, two 

 filmy but very tough shreds, united to the portion that includes the 

 head-piece. This portion consists of the head, antenna- and mouth- 

 parts, and the anterior legs. These filmy shreds are, in fact, the pupal 

 investment of that part of the prothorax that is covered by the append- 

 ages in the pupa, as well as the basal portion of the leg-cases. It 

 takes its attachment ventrally (one is apt to fall into familiar, but 

 inaccurate, language and say in front, though front is opposed to back, 

 and is so far correct, but is also synonymous with anterior, which 

 would be wrong) to the points of the femoral pieces, the pieces that in 

 these pupae look so like maxillae or labial palpi. The front piece thus 

 tethered leans outwards, and forms the slope of the funnel-shaped 

 aperture in front (as opposed to back). To the same point the second 

 leg-pieces remain fixed by one end, the other ends slope outwards and 

 form sides to the funnel. From this point also extends directly back- 

 wards (as opposed to forwards) another cable of filmy chitin, which is 

 attached by its other extremity to the end of the wings where they 

 form part of the solid pupal mass. This is no doubt the pupal covering 

 of both the mesothoracic femora, and it fastens these face-pieces down 

 solidly in position against the opening of the sack. We have, then, 

 within the sack, the undivided mass of the pupa-case as far forwards 

 as the 3rd thoracic and the anterior wing-cases of the 2nd thoracic, 

 outside the sack, but closely appressed to its mouth, a ring formed of 

 the 1st thoracic parts, both the dorsal portion that is exposed and the 

 ventral portion that is covered, in the pupa. This ring carries other 

 parts, so as to make a funnel-shaped opening, viz., the head- and face- 

 parts, the leg-cases of its own segment and of the 2nd thoracic. Its 



