HEAD, MOUTH-PARTS, ORTHOPTERA EUPLEXOPTERA 273 



is smaller than the distal one, except in Mantis and Anisolabis. 

 The distal segment is long, cylindrical, clavate, and its hemi- 

 spherical tip is covered with minute conical setae in Gryllus, 

 Orchelimum, Stenopelmatus, and Melanoplus, and is more or 

 less depressed in Diapheromera and Tettix. In Anisolabis the 

 last segment is clavate and smaller than the second and its tip 

 bears a small, cuticular papilla (fig. 137). The labial palpi are 

 nearly straight in Mantis, but are more or less geniculate in 

 other genera. * 



The prepharynx of generalized biting insects consists of a well- 

 differentiated propharynx (prx), parapharynx (ppx), and ambi- 

 pharynx (ax). The propharynx is dorsal in position and in- 

 cludes the epipharynx (ex), a pair of tormae {tm), and the 

 epigusta (eg). The parapharynx is ventral in position, is lingui- 

 form, and consists of two parts, the proximal basipharynx (bx) 

 and the distal hypopharynx (hx). The former includes the 

 pharyngeae (prg), the paralinguae (pin) with the linguacutae 

 (Ig) which bears the linguatendons (Ig), the lingulae (In), and 

 the subgusta (su); while the latter includes a pair of saliviae 

 (si), which support the salivos {so), and the ventral membranous 

 oscula (ox). That part of the pharynx caudad of the pre- 

 pharynx is the postpharynx (pox). It is well to remember 

 that the parapharynx corresponds approximately to the 'hypo- 

 pharynx' of most writers. 



The prepharynx of Blatta (figs. 151, 152, 153, and 154) in- 

 cludes all the parts enumerated above. The epipharynx is the 

 same in size and shape as the labrum and the surface is concave 

 near the cephalic margin. The tormae are the distinct, brown- 

 ish, X-shaped sclerites. One arm of the X extends to the 

 laterocaudal angle of the labrum, forming on the dorsal aspect, a 

 distinct landmark for the lateral end of the clypeolabral suture 

 and another arm extends caudad for a short distance, where it 

 disappears from the surface, becoming an ental bar to which 

 the principal retractor muscles of the labrum are attached. The 

 other two arms of each torma extend mesad and enclose a clear 

 membranous circular area which is provided with minute sen- 

 sory pits. A brownish claw-shaped chitinized area, extending 



