THE EXTERNAL MORPHOLOGY OF THE LEPIDOPTEROUS PUPA. 41 



cease to have any morphological significance, and this is also rendered 

 probable by the fact that closely allied pupa; are altogether without it, 

 &c." For the upper (cremastral) portion of the 10th abdominal pupal 

 segment, Poulton has suggested the term " rostral," restricting the 

 term " anal " to the lower portion, the analogue of the anal prolegs. 



The head of the lepidopterous pupa consists essentially of the 

 clypeus (or face-piece), the dorsal head-piece (the segment of the head 

 in contact with the front edge of the pro thorax), and a separate piece 

 (only existent in some of the most generalised forms) placed between 

 the clypeus and the dorsal head-piece, and which Chapman says is 

 probably " a portion of the anterior head-cover or face-piece." It does 

 not, he says, " divide in the middle line on dehiscence, but remains in 

 one piece ; it is probably the dorsal-plate belonging to the antennal 

 section of the head, as distinguished from the face-piece proper which 

 is the anterior plate (or plates) belonging to the mouthparts." The 

 eyes occupy a large portion of the lateral area of the clypeus, the 

 glazed eye being generally conspicuous, and stretching from the base 

 of the antennas to the base of the first pair of legs. It may be that it 

 is more correct to describe the eye as occupying the whole of the side- 

 pieces of the head, as usually seen, the dorsal head-piece, when present, 

 including the remainder. 



The thoracic segments of the lepidopterous pupa are generally well 

 marked, clearly defined, and separated from each other by distinct 

 sutures. The prothorax is attached in front to the head segments, the 

 mesothorax carries the pupal fore-wings, and the metathorax the pupal 

 hind-wings. The prothoracic spiracle is usually buried well in the 

 suture between the prothorax and mesothorax, more or less dorso- 

 laterally. The abdominal segments are usually clearly defined and 

 separate, and the segmental incisions well-marked, movable on each 

 other in the pupa-libera, variable as to the number of movable inci- 

 sions in the pupa-incompleta and pupa-obtecta, segments 8, 9 and 10, 

 however, being always united into one mass. Chapman notes that the 

 abdominal segments of the pupa of Eriocrania are all " free." In 

 the Cochlidids, segments 1-6 are free, i.e., none of them are soldered 

 to the wings and appendages, and they appear to be capable of inde- 

 pendent movement on each other. It may be here noted that the 

 abdominal segments 1-2 are so closely applied to the appendages, and 

 that the soldering is so delicate in the pupa? of Nepticulids, Adelids, 

 &c, that it is almost impossible to say whether they are actually free 

 or not. Packard says that in the Prodoxidae the abdominal segments 2-9 

 are free, and armed with enormous dorsal spines. In all lepidopterous 

 pupa? each of the abdominal segments 1-8 bears spiracles ; strangely 

 enough the pair on segment 8 are completely aborted and function- 

 less, although their larval homologues are especially well-developed. 

 There are also certain superficial marks on the abdominal segments 

 of some pupa?, which have, so far as is known, no functional value and 

 are, apparently of no morphological value. They are remnants of the 

 larval structures, and constitute depressions in the position of the pro- 

 legs, as well as in the positions of the more pronounced larval tubercles, 

 and sometimes, even, occupy the place of the hairs (the latter them- 

 selves being also present in many pupa?), and being homologous both 

 in nature and position with those of the larva. Colours, characterising 

 the adult larva and observable in the early pupal stage, Poulton 



