42 



superfamily. The opening is on the dorsum in the normal position, 

 and is very large, with a strongly arched cephalic margin; but the 

 spiracle is on the ventral surface directly under the sculptured eye- 

 piece in Megalopygidae and Eucleidae, and a little farther laterad in 

 Pyromorphidae so that it comes partly under the antennae. The 

 spiracle, with the adjoining parts slightly pushed aside to show their 

 relation, is seen in Figure 21. The family Pyromorphidae being more 

 specialized than the other two families differs from them considerably, 

 but its relationship to them is evident. The three families included 

 here may be separated as follows : 



a. Dorsum of abdominal segments with spines on the cephalic part and 

 a covering of coarse setae on each caudo-lateral part which does not 

 usually extend to the meson; maxillae simple quadrangular pieces, 

 without any lateral prolongations; a large conical tubercle caudad 

 of each abdominal spiracle on segments 2-6 ; mesothorax never ex- 

 tending caudad to the first abdominal segment Megalopygidae. 



aa. Dorsum of abdominal segments with short spines, but never with a 



covering of coarse setae on any part ; tubercles never present caudad 



of any of the abdominal spiracles. 



b. Labial palpi present; mesothorax with a long mesal lobe reaching 



on to the first abdominal segment ; maxillae always less than half 



the length of the wings " Pyromorphidae. 



bb. Labial palpi absent; mesothorax never with a long mesal lobe 

 reaching on to the first abdominal segment ; maxillae more than 

 half the length of the wings Pyromorphidae. 



Family Megalopygidae 



The Megalopygidae have the head and thoracic segments free, also 

 abdominal segments 1-7 in the male and 1-6 in the female. The ap- 

 pendages are entirely free from each other and from the body wall. 

 The body is soft and covered with a thin, delicate, transparent cuticle 

 which is slightly chitinized. There are always setae on the dorsum 

 of the abdominal segments as well as spines. The setae are found on 

 each side of the meson on the caudal half of all the segments. The epi- 

 cranial suture is distinct but all the other head sutures are obliterated. 

 The front has a distinct projection and the mandibles show as dis- 

 tinctly elevated tubercles. The size and arrangement of the parts 

 may be seen in Figures 17 and 18. This family together with the 

 Eucleidae possesses a very peculiar eye-piece. Chapman ('94, p. 349) 

 called attention to this structure and spoke of it as the "eye-flange". 

 This eye-piece, in reality the sculptured portion, is free along its 

 lateral and caudal margins and extends well out on to the antennae. 



