NO. 4 FEEDING MECHANISM OF LEPIDOPTERA — SCHMITT 



15 



large muscle. This is illustrated in figure 7 B, showing the muscula- 

 ture of Pieris rapae. The migrant is marked atp2, and it really passes 

 laterad of the posterior tentorial proboscis extensor, its strands insert- 

 ing with those of the anterior tentorial proboscis extensor which origi- 

 nate on the anterior arm. Papilio polyxenes, P. troilus, and P. inar- 

 ccllus show similar conditions. Sometimes there is a continuous band 

 of muscle from the clypeus to the anterior arm of the tentorium. 



PoR 



PoR 



atp — 



s^^""C 



Fig. 7. — Proboscis extensor musculature. 



A, right half of head, mesal view, of Bornbyx niori, as exposed by median 

 sagittal cut. B, same of Pieris rapae. C, left half of head of Pieris rapae, 

 showing interior by removal of eye. D, right half of head, mesal view, of 

 Epargyreus tityrus, as exposed by median sagittal cut. 



In the Pieridae this modification is more complete, with the " mi- 

 grant " atp2 originating higher on the clypeus than in the Papilionidae. 

 In Pieris protodice, the checkered white, this muscle originates just 

 anterior of the antennal socket. The musculature of Pieris rapae is 

 illustrated in figure 7 B. Other pier ids examined included Colias eury- 

 theme and Anthocharis genutia. 



By eliminating the cranial proboscis extensor, the Papilionidae and 

 Pieridae seem to have considerably narrowed the parietal area, or per- 



