150 



life. There is a tendency for the generalized forms to emerge from 

 the mine, cocoon, burrow, or other place of protection, as a pupa, and 

 consequently the body is provided with some structure which assists 

 in its progress. The appendages and body segments are usually sep- 

 arated from each other at dehiscence and the body splits along the 

 median line of the vertex and thoracic segments, the vertex carrying 

 the sculptured eye-pieces with it. The front, with the antennae, is com- 

 pletely separated from the rest of the head parts in some forms, by a 

 splitting along the epicranial suture on the dorsum, and along the 

 fronto-clypeal suture on the ventral surface. When the fronto-clypeal 

 suture is not entire it usually splits for a part of its length, thus al- 

 lowing it to be considerably elevated. In specialized forms it is usually 

 the imago which emerges, the pupal skin being left behind in the 

 cocoon or other place of protection. The appendages and body seg- 

 ments remain firmly soldered together and the imago escapes through 

 the opening made by the splitting of the vertex, when present, the pro- 

 thorax, and the mesothorax; or, if this is not sufficient, an irregular 

 opening which does not follow the line of any suture is made in the 

 cephalic end of the body. In these forms the eye-pieces remain at- 

 tached to the other face-parts. 



The phylogeny of any group is usually determined by the devel- 

 opment of a single character. Many workers have used the venation 

 of the wings to arrange a series of genera or species in phylogenetic 

 order. Others have used the genitalia, or the arrangement of setae. 

 The pupae present many and varied characters which may be used to 

 arrange such a series. In this investigation a series was arranged for 

 each of the characters previously mentioned and the results of these 

 series were combined. These characters have the advantage over 

 those used by previous authors in that they comprise practically all of 

 the important structures of the body and are all present in the same 

 individual. It is quite probable that other characters might be used 

 to indicate the development of the order, such as the number and ar- 

 rangement of the genital apertures, the form of the spiracles, and the 

 arrangement of setae, none of which have been investigated sufficiently 

 to admit of their use in this paper. 



Acknowledgments 



The subject for this investigation was suggested by Professor A. 

 D. MacGillivray in September, 1912. Since that time many species of 

 Lepidoptera have been collected, both in the larval and pupal stage, 

 and reared to maturity. The Graduate School of the University of 



