330 



THE STUDY OF INSECTS. 



as long as the body ; but in one subfamily it is short and 

 membranous. When not in use it is closely coiled like a 

 watch-spring beneath the head. None of the species have 

 ocelli. 



The venation of the wings (Fig. 407) is quite character- 

 istic ; the most distinctive feature is the presence of what 



ni, in, 



ii 



XI 



VII 



VII 



FIG. 4^.7. Wings of Phlegethontiws ccleits. 



appears to be a cross-vein between subcosta and radius of 

 the hind wing. This apparent cross-vein is due to the fact 

 that veins II and III are grown together for a short distance, 

 and then vein II separates and joins vein I. The obvious 

 presence of vein I in the hind wings is unusual ; but it occurs 

 in the Psychidae, in the Bombycidae, and in the Anthroceridae 

 (a family not represented in our fauna) also. This basal part 

 of vein I is probably preserved in other cases where it appears 

 to be the base of vein II. Thus in Citheronia (Fig. 417) there 

 is a rudiment of the so-called cross-vein, which has entirely 

 disappeared in the more specialized forms of the family to 



