149 



The fronto-clypeal suture is visible for a part of its length in most 

 pupae, and is especially distinct for its entire length in some of the 

 Gelechioidea ; but dehiscence often showed the presence of this suture 

 when it was impossible to locate it on the pupa. The part of this su- 

 ture adjacent to the proximal end of each antenna is the last head su- 

 ture to be obliterated, and it is lacking only in the Saturnioidea. 



The segments of the body are more nearly of equal length in gen- 

 eralized than in specialized forms, especially in the abdomen. The 

 prothorax is short in the Micropterygoidea and becomes gradually 

 longer in the specialized superfamilies. The metathorax is long in 

 generalized forms and nearly equals the mesothorax in length. As 

 specialization proceeds, the mesothorax becomes longer and the meta- 

 thorax much shorter, so that the comparative length of these two seg- 

 ments furnishes another means of determining the position of a super- 

 family in the series. The abdominal segments also become consoli- 

 dated, first at the caudal end of the body, where they gradually be- 

 come shorter than the cephalic segments. After motion is lost in the 

 cephalic segments, they, too, gradually shorten, until the movable seg- 

 ments are much longer than any of the others. 



The presence of visible maxillary and labial palpi also furnishes 

 an easy means for the identification of generalized forms. The labial 

 palpi are retained throughout the series, but are gradually overlaid and 

 concealed by the maxillae. The presence or absence of visible labial 

 palpi, however, indicates the degree to which specialization has pro- 

 ceeded along a given line. Labial palpi are visible to some extent in 

 some members of all superfamilies except the Saturnioidea. The 

 maxillary palpi are usually the first to disappear, but these palpi are 

 often present in the pupa, when lacking in the imago. The maxillary 

 palpi in generalized forms reach the proximo-lateral angles of the 

 maxillae, but gradually decrease in length until they are visible only 

 as a small triangular area caudad of the sculptured eye-piece. 



When the appendages are free their position is considerably laterad 

 of that which they gradually assume as they become soldered to each 

 other. The legs are folded in such a way that in generalized forms 

 almost the entire femur of the prothoracic leg is exposed. Later the 

 tibia and tarsus of this leg are folded so that their position is nearer 

 the meson than formerly and the femur is entirely concealed. The 

 presence of an exposed portion of the prothoracic femur is a general- 

 ized condition which is retained by forms exceedingly specialized in 

 other respects, and is found in some genera of Sphingidae. 



As to the method of dehiscence, there are several things to be 

 noted, although all too little is known of this interesting phase of pupal 



