HEAD, MOUTH-PARTS, ORTHOPTERA EUPLEXOPTERA 283 



and extends toward the rectotendon of the mandible. The 

 prominent X-shaped sclerite cephalad of each parahngua is the 

 hngula, the lateral aspect of which is concave and is produced 

 into a strongly chitinized caudal arm and a narrow arm which 

 is reflected ventrocephalad. The transverse arm of each lingula 

 apparently fuses on the meson with the one on the other side. 

 A narrow^ semicircular projection, extending caudad from the 

 mesal end of each transverse arm, touches the cephalic end of 

 the paralingua and a prominent mesal spinulate ridge caudad of 

 the lingulae. The subgusta is concave and carinate as noted 

 above. The distal end of the hypopharynx is trilobed. The 

 median lobe is large, symmetrically triangular, and its apex is 

 pointed. Each lateral lobe is concave on its mesal aspect and 

 overlaps the lateral margin of the proximal part of the median 

 lobe. On the ventral two-thirds of each lateral aspect of the 

 hypopharynx is a large, moderately chitinized, convex sclerite, 

 the salivia. Its caudal angle is produced into a mesal arm sup- 

 porting the salivos on the ventromeson. The ventral aspect of 

 the hypopharynx is deeply concave near the proximal portion, 

 but the median third is notably convex, while the distal third is 

 membranous. A narrow chitinized area extends cephalad along 

 the lateral margin of the hypopharynx and supports the ventro- 

 mesal part of the lateral lobe. The mesal arms of the saliviae 

 form on the ventromeson a cone-shaped structure whose apex is 

 directed caudad and whose cephalic margin is arched over by a 

 narrow transverse bar which is provided with a small median 

 notch. The cone is fused solidly to the strongly chitinized 

 V-shaped vertical frame which arises from the keel-like ental 

 ridge at the base of the mesarima of the labium. The salivary 

 duct is moderately large and attached to the caudal end of the 

 cone and its opening is at the median notch of the transverse 

 bar. There is a distinct asymmetry of parts on the dorsal 

 aspect of the hypopharynx. The dextral ligula is straighter 

 and narrower than the sinistral, but its cephalic process on the 

 meson is very much larger than the sinistral; the right paralingua 

 is slightly in advance of the left, and the sinistral lateral lobe of 

 the hypopharynx is smaller and overlaps the median lobe to a 



