40 



erably elevated. The legs are scarcely developed, being represented 

 by transverse chitinized elevations on the venter of the thoracic seg- 

 ments. The abdominal segments are much as in the male. They 

 show on the venter the proleg scars, on the dorsum the rows of 

 toothed chitinized ridges and setae, but the body setae are much 

 smaller and difficult to distinguish and are not represented in the 

 figure. A single genital opening is found in the female, on the eighth 

 abdominal segment. No hooks are present at the caudal end of the 

 body. The abdominal spiracles are present on the first eight abdom- 

 inal segments, but there is no visible opening for the mesothoracic 

 spiracle in either sex. The only genera available for study were 

 Thyridopteryx and Oiketicus. These resemble each other very closely 

 and the difference between the pupae can hardly be considered as 

 generic. The pupae of Oiketicus are larger and stouter, the males 

 examined averaging 18 mm. in length, while those of Thyridopteryx 

 were slenderer and only 15 mm. in length. The two genera may be 

 separated thus : 



a. Abdominal segments 2-G with a caudal row of setae, the row on the 

 the sixth interrupted and shorter than the other rows ; caudal spines 

 stout and simple ; spiracles scarcely produced beyond the surface 

 of the body except at their cephalic margins. 



Thyridopteryx Stephens. 

 aa. Abdominal segments 2-5 with a caudal row of setae, no row on the 

 sixth ever present ; caudal spines slender and with a distinct tooth ; 

 spiracles distinctly produced beyond the surface of the body. 



Oiketicus Guilding. 

 The following species were examined : 

 Thyridopteryx ephemeraeformis Haworth 

 Oiketicus abbotii Grote 



Family Cossidae 



The Cossidae are borers in the larval stage and seem to be very 

 closely related to the Hepialidae, although they resemble them less 

 than do the Psychidae. This family has segments 3-7 of the abdomen 

 free in the male and 3-6 in the female. There is another sexual dif- 

 ference to be noted, viz., the presence of an extra row of spines on 

 the abdomen of the male. In this sex the seventh segment has two 

 rows of spines and the succeeding segments one row ; in the female 

 the sixth is the last segment with two rows, the remaining caudal seg- 

 ments having but one row. The epicranial suture is not distinct in 

 any species, but at dehiscence Prionoxystus robiniae shows a small 

 piece of the vertex on each side of the meson, and this with the con- 

 junctiva bears the eye-pieces. The lateral part of the fronto-clypeal 

 suture is distinct and the clypco-labral suture is always visible. 



