6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



21. Ventral (posterior) muscle of the labium (figs, i, 3). — Arises 

 laterally on the tentorial bridge at the posterior end of the anterior 

 tentorial arm and is inserted laterally on the base of the prementum. 



22. Muscle of the prementum (figs, i, 3). — Arises medially in the 

 posterior region of the submentum and is inserted slightly laterally 

 on the base of the prementum. 



23. Depressor muscle of the labial palpus (figs, i, 3). — Arises 

 centrally on the dorsal wall of the labium at the base of the glossa 

 and is inserted dorsally on the base of the palpus. 



24. Levator muscle of the labial palpus (figs, i, 3). — Arises later- 

 ally at the base of the prementum and is inserted posteriorly on the 

 base of the labial palpus. 



25. Muscle of the labial palpus (figs, i, 3A). — Arises laterally on 

 the prementum and is inserted basally and somewhat dorsally on the 

 second palpal segment. 



26. Muscle of the labial palpus (figs. 3, 3A). — Arises in the middle 

 region of the ventral (posterior) wall of the first palpal segment and 

 is inserted ventrally (posteriorly) in the middle region of the base 

 of the third segment. 



27. Muscle of the labial palpus (figs. 3, 3A). — Arises anteriorly 

 at the base of the first palpal segment, inserted on the third segment 

 basally on the anterior margin. 



28. Flexor muscle of the glossa (fig. 3). — Arises medially at the 

 base of the prementum and is inserted on the ventral wall of the 

 labium at the base of the glossa. 



29. Flexor muscle of the paraglossa (fig. 3). — Arises on the ven- 

 tral wall of the labium at the base of the prementum and is inserted 

 basally on the ventral wall of the paraglossa. 



30. Ventral dilator muscle of the pharynx (fig. i). — Arises on the 

 tentorium and is inserted medially on the pharyngeal region just 

 within the mouth. 



31. Lateral dilator muscles of the pharynx (fig. 2). — Arise later- 

 ally on the dorsal head region adjacent to the inner margin of the 

 compound eye posterior to the muscle of hypo pharyngeal bar Y , 10, 

 branch A, and are inserted on the side of the pharynx ventrad of 

 the dosal dilator muscle of the pharynx, 11 (fig. i), 



32. Dorsal apprcssor muscle group of the cibariuvi (fig. 2). — 

 Arises on the dorsal pharyngeal surface posterior to the frontal 

 ganglion and extends anteriorly beneath the compressor muscle group 

 of the cibarium, 12, to be inserted on the dorsal wall of the cibarium 

 adjacent to the anterior limits of muscle 12. These muscles are found 

 in a well-developed state in the specimens used in this work only in 

 Orthoptera, Dermaptera, and Neuroptera. 



