JOUKNAL OF ENTOMOLOGY AND ZOOLOGY 101 



the invaginations for the anterior arms of the tentorium (Fig. 12, 

 at) are larger and more prominent than in the forms previously 

 considered and located along the lateral margin of the clypeus. The 

 mandibles are four-toothed and heavily chitinized. Mesad of these 

 are the maxillae (Fig. 12, mx) which are shorter than the head, 

 rather broad at base, with a distinct projection on each lateral mar- 

 gin but showing no traces of maxillary palpi. The labial palpi 

 (Fig. 12, Ip) show on each side the meson between the two halves 

 of the maxillae, the proximal segments larger than the distal ones, 

 which are globular in the pupa, but ovoid in the preimago. 



Following these a study was made of the mouth-parts of six 

 genera of the superfamily Saturnioidea. These showed little varia- 

 tion and were very similar to the mouth-parts of Sthenopis thule 

 and Hemerocampa leucostigma for, like these species, the mouth- 

 parts are functionless in the adult. It was noticed in all these forms 

 that the appendages were much more ciistinct in pupae than in the 

 preimagos. The mandibles, which in the adult seem but projec- 

 tions from the genae, are plainly appendages in the pupa with the 

 proximal suture distinct and also the articulation with the clypeus. 

 The latter can not be seen in the preimago, but the proximal suture 

 is usually distinct, the mandible being more heavily chitinized and 

 more plate-like in this stage. The maxills show much difference 

 in the stages of their development, being larger at first and usually 

 more closely approximated in the younger stages, gradually becom- 

 ing contracted and farther apart in the preimago. The maxillae 

 show varying degrees of development in the different genera. Max- 

 illary palpi were not found in all the genera studied, but lack of ma- 

 terial prevented a study of the earlier stages of some forms and it 

 may be that further study would show them to be always present. 

 In every case there is a projection at the base of each maxilla, where 

 the palpi are located when present. 



The labial palpi are always present and show about the same de- 

 gree of development, although the number of segments varies in 

 different species. 



The six genera of Saturnioidea studied are as follows: Citheronia 

 recalls, Dryocampa ruhicunda, Automeris io, Telea polyphemtis, 

 Callosamia promethea and Samia cecropia. 



