10 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I23 



of the cockroach that go from the hypopharyngeal fulcrum to the 

 prementum. The hypopharyngeal apodeme of the dragonfly larva is 

 clearly a special development functionally correlated with the speciali- 

 zation of the labium ; it is either greatly reduced in the adult (fig. 

 6 G, hAp), or represented by a ligament. 



dicb cb <'':'="sr 



Fig. 4. — Anax Junius (Drury), hypopharyiix and cibarium of larva. 



A, longitudinal section of head to left of hypopharynx and cibarium. B, hypo- 

 pharynx, anterior. C, transverse section through cibarium and hypopharynx, 

 anterior. D, hypopharyngeal apodeme and salivary duct, dorsal. E, hypopharyn- 

 geal apodeme, ventral. 



Cb, cibarium ; Clp, clypeus ; dlcb, dilator muscles of cibarium ; jrGng, frontal 

 ganglion; hAp, hypopharyngeal apodeme; Hphy, hypopharynx; Lni, labrum; 

 Mth", functional mouth ; slDct, salivary duct ; slO, opening of salivary duct ; 

 Stom, stomodaeum ; tmcls, constrictor muscles of cibarium; zv, transverse bar 

 of hypopharyngeal suspensorium ; y, oral arm of same. 



13, frontal muscle of hypopharyngeal suspensorium ; 16, tentorial muscle of 

 hypopharyngeal apodeme ; 29, hypopharyngeal muscle of mandible. 



The anterior surface of the hypopharynx is continued upward into 

 the floor of a long, preoral cibarial pouch (fig. 4 A, Cb), the dorsal 

 wall of which is covered by strong, transverse constrictor muscles. 

 Paired dilator muscles (dlcb) arising on the clypeus penetrate between 

 the transverse fibers to be inserted on the cibarial roof (C), which 



