276 HACHIRO YUASA 



The epipharynx is setiferous, membranous, and usually con- 

 cave and is similar in size and shape to the labrum. The sur- 

 face bears setae and spinulae which are local in their distribu- 

 tion in Gryllus and others. There are often chitinized structures 

 which are usually more distinct on the ental than on the ectal 

 surface and which may be Y-shaped as in Melanoplus or wedge- 

 shaped as in Gryllus. 



The tormae are always present, distinct, well chitinized, and 

 twisted, and bear definite relation to the clypeolabral suture. 

 The dorsal arm of the twisted body is attached to the lateral 

 angle of the suture and the ventral arm to the caudolateral angle 

 of the epipharynx, while the body of each torma connects the 

 two arms. There is a variation in size, shape, and complexity 

 from the simple type found in Stenopelmatus to the many- 

 branched type of Gryllus. The mesal ends of the tormae are 

 sometimes connected by a thickening (fig. 159). 



The epigusta is membranous and often includes a few tendinous 

 thickenings. It is frequently spinulate and bears thickenings 

 and sensory pits. It gradually merges with the postpharynx 

 and ambipharynx; there is never a sharp line of demarcation 

 between them. The epigusta is never extensive. 



The ambipharynx is membranous and not well differentiated. 

 It is usually restricted by the encroachment of the mandibles. 

 In Gryllus it is spinulate near the entrance to the postpharynx 

 and bears a small chitinized area cephalad of each mandible. 



The parapharynx is well developed and, since it is complex in 

 organization, and since there is no adequate description published, 

 it will be described with more or less detail. The distribution 

 and localization of the setae and spinulae on the chitinized and 

 membranous portions of the parapharynx differ considerably. 

 The asymmetry of the surface structures observed in many 

 genera (Gryllus, Tettix, Anisolabis, and others) is due to the 

 adjustment necessary to secure the close fitting of different 

 elements of the mouth-parts, both when in repose and in use. 



In Mantis (fig. 161) the parapharynx resembles that of the 

 cockroach. The pharyngea is distinct, slightly chitinized, and 

 extends caudad along the ventrolateral margin of the subgusta 



