148 



nient is covered by the wings, therefore it can not be considered as a 

 free segment. In many cases, however, dorsal movement of such seg- 

 ments is possible, which gives the segment freedom of movement in 

 certain directions; as, for instance, in curving the caudal end of the 

 body cephalad on the ventral surface, well illustrated in the movements 

 of most tortricids. Such forms must be considered as more general- 

 ized than those which have lost entire motion of the segment, and thus 

 the Pyralidoidea and Papilionoidea must occupy a lower position than 

 the Yponomeutoidea, whose members have lost dorsal motion of the 

 third abdominal segment, while the other two superfamilies mentioned 

 retain it. There are certain specialized forms in other superfamilies 

 in which motion is lost in all the body segments, notably in the family 

 Elachistidae of the Gelechioidea and in certain genera of the family 

 Nymphalidae in the Papilionoidea. There are also many genera in 

 various families which retain movement in only one segment. 



The appendages of the generalized pupae are entirely free from 

 each other and from the body wall and are often considerably spread 

 out from the surface of the body so that the pupae strongly resemble 

 those of the Trichoptera. In these forms there is but a slight degree 

 of chitinization in any part of the body. The appendages are grad- 

 ually soldered down, however, first to each other, while all remain 

 free from the body wall, and then there takes place a gradual sol- 

 dering down of the appendages to the body wall, beginning first at 

 the cephalic end of the abdomen. In many pupae the appendages are 

 soldered to two, three, or four abdominal segments while the portion 

 of the appendages caudad of these segments remains free and allows 

 freedom of motion of the abdominal segments underneath. Such a 

 condition exists in many genera of the Aegerioidea and Gelechioidea. 

 The pupae with free appendages could only exist successfully in pro- 

 tected situations from which an easy egress was possible, and so they 

 are only found in cocoons, or in mines in leaves and stems of plants. 

 Pupae with any other environment lost the freedom of the appendages 

 much more rapidly, as in the case of the Lyonetiidae and some of the 

 Papilionoidea. 



The number and arrangement of the sutures present on the head 

 has already been discussed under the head of external morphology, 

 pages 23 to 25. These sutures are gradually obliterated, beginning 

 with the clypeo-labral, which is lost among very generalized pupae. 

 The epicranial suture is one of the last to disappear, and its presence 

 indicates the degree of specialization in many of the higher forms, as 

 it is retained in some members of many superfamilies which are high 

 in the series. 



