no 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



median surface (fig. 42 B, C) is a ridge, bordered by long hairs di- 

 rected inward and upward, that continues dorsally from the narrowed 

 end of the hypopharynx, and which is excavated by a median channel 

 where it enters the mouth. At each side of this channel is an oval 

 group of sense organs. Flanking the ridge are two chitinous bars 

 (HS), the ventral ends of which articulate with the anterior extrem- 

 ities of the lateral basal rods of the hypopharynx (w). Dorsally 

 each bar forks into two arms, of which one (x) goes posteriorly to 



Fig. 42. — The epipharyngeal surface, and the hypopharynx of Dissosteira 

 Carolina. 



A, epipharyngeal surface of clypeus and labrum, and ventral extremity of 

 pharynx. B, lateral view of mouth opening, and of suspensorial apparatus of 

 hypopharynx. C, antero-ventral view of hypopharynx and its suspensory rods. 



9Ap, apodeme of adductor muscle of mandible ; Clp, clypeus ; Hphy, hypo- 

 pharynx ; HS, suspensorial bar of hypopharynx ; Lm, labrum ; in, Y-shaped ridge 

 in epipharyngeal wall of labrum ; Mth, mouth ; Phy, pharynx ; Pnt, small lobe 

 behind angle of mouth, possibly rudiment of tritocerebral appendage; Tor, 

 torma ; iv, lateral basal bar of hypopharynx ; x, mandibular branch of sus- 

 pensorial bar (HS) of hypopharynx; y, oral branch of same. 



the base of the adductor apodeme of the mandible (pAp), and the 

 other (y) goes anteriorly, laterally, and dorsally into the angle of the 

 mouth, where it forms a support for the insertion of the retractor 

 muscle of the mouth angle (A, B, ^8). 



The two lateral bars (fig. 42 B, HS) in the space between the hypo- 

 pharynx and the mouth, with their posterior dorsal arms (x) braced 

 against the bases of the mandibular apodemes. and their ventral 

 ends articulated with the basal rods (zv) of the hypopharynx, consti- 

 tute a movable suspensorial apparatus of the hypopharynx. It is 

 evident that a contraction of the mouth angle muscles (38) inserted 



