HEAD, MOUTH-PARTS, ORTHOPTERA EUPLEXOPTERA 257 



connected with the flexible membrane which is attached to the 

 scape of the antenna. There is a narrow pointed projection, 

 antacoila (aa), extending caudad from the cephaUc margin of 

 the antennaria (fig. 54). This is the 'chitinized pin' of Miall 

 and Denny ('89). Another fine slender bar is attached to the 

 caudal margin of the scape. These two projections, together 

 with the antatendons (at) control the movements of the antenna. 

 The minute chitinized spots (ch) in the antacoria mark the at- 

 tachment of these tendons. The antennariae are always pres- 

 ent. The articulation of the antennae is either like that of the 

 cockroach, as in Mantis (fig. 56) and Anisolabis (fig. 61) ; by means 

 of less definite projections, as in Gryllus (fig. 60), Stenopelmatus 

 and Melanoplus, or by means of the triangular projection of the 

 scape which fits into the emargination of the antennaria (fig. 62) . 

 There are two antatendons, and their points of attachement can 

 be identified in all the genera. 



The pretentorina (pn) in Blatta (figs. 1 and 2) is the linear, 

 transverse furrow along the caudomesal margin of each man- 

 dibularia. In all the genera studied, with a possible exception of 

 Anisolabis, the pretentorinae are distinct and definite in their 

 location and afford excellent dependable landmarks in orienting 

 other structures. Although they are always associated with the 

 front, mandibularia, frontogenal and mandogenal sutures, they 

 differ somewhat in their extent and appearance. The lateral or 

 caudal portion of each pretentorina terminates either on the fron- 

 togenal suture, more or less remote from the mandibularia, as 

 in Blatta, Mantis, and Anisolabis, or on the mandogenal suture 

 beyond the cephalic end of the frontogenal suture, as in Gryllus, 

 Melanoplus, and others. 



The suture forming the caudal margin of each mandibularia 

 and separating it from the vertex or gena and front is the mando- 

 genal suture {mgs) . This suture is present, except in Anisolabis, 

 but varies in length and direction on account of the differences 

 in size, shape, and position of the mandibularia. 



The mandibularia {mb) in Blatta (fig. 2) is the small triangular 

 area extending from the precoila to the cephalic end of the occip- 

 ital suture and, on its cephalic margin, which is often submem- 



