3OO ARTHUR D. WHEDON. 



PLATE II. 



FIG. 8. Right half of the head and flexed labium of the larva as viewed from 

 the inner aspect. Parts of the tracheal branches which lie between the adductor 

 muscles are omitted. X 9. 



FIG. 9. Left half of the labium shown in Fig. 8, so placed as to illustrate, 

 together with Fig. 8, the complete labium opened like a book. In Fig. 9 the 

 adductor muscle has been dissected away to give a complete view of the mechanism 

 for extension and flexion. Chitinized processes are stippled. X 9. 



FIG. 10. Left half of the extended larval labium as seen from the interior. 

 A large portion of the base of the adductor muscle is dissected away to uncover 

 the extensor and flexor muscles. The primary and secondary flexors should be 

 especially noted. X 9. 



FIG. ii. The flexed larval labium viewed from the exterior right side, the 

 muscles showing through the transparent skeleton. X 9. 



FIG. 12. Ventral view of the mentum and the main hinge of the larval labium 

 when flexed. All internal parts seen through the skeleton. X 9. 



FIG. 13. Dorsal view (with labium flexed, ventral when extended) of the 

 submentum of the specimen shown in Fig. 12, illustrating the attachments of 

 muscles. X 9. 



