264 HACHIRO YUASA 



lateral angles of the antennariae; in Tettix (fig. 52) they are 

 attached on the front cephalolaterad of the antacoriae; and in 

 Anisolabis (fig. 53) near the caudomesal margins of the com- 

 pound eyes. In others they are directed laterodorsad or latero- 

 dorso-caudad toward the antacoriae or points near them and are 

 apparently unattached. 



B. Movable parts of the head 



The antennae (a) of Blatta'(figs. 54 and 55) are long, slender, 

 setaceous, and multisegmented. The scape (sc), pedicel (p), and 

 the segments of the flagellum (fl) are cylindrical and setigerous. 

 The proximal margin of the scape is emarginate, forming an 

 antartis (ad), and articulates with the antacoila (aa). Two 

 antatendons (at) are attached to the scape near the emargina- 

 tion. The first segment of the flagellum is longer than the pedi- 

 cel in the female and shorter in the male. The antennae of 

 other species are either filiform or setaceous and articulate with 

 the antennaria. The scape is quadrate and flattened in Gryllus 

 (figs. 59 and 60) and elongated in Anisolabis (fig. 61). 



The mandibles (md) in Blatta (figs. 70, 72, and 73) are convex 

 on the dorsal aspect and concave on the ventral. The preartis 

 (py) is a combination of condyle and acetabulum, and is located 

 on the dorsal aspect, while the postartis (ptc) is globular, prom- 

 inent, and situated near the lateral margin of the ventral aspect. 

 The small spatulate extensotendon (et) is attached near the post- 

 artis and the large branched rectotendon (rt) to the proximal 

 part of the mesal margin on the ventral aspect. The acia (ac) 

 is well differentiated and the mola (ml) is the triangular tooth 

 cephalad of the acia. The dentes (d) are sharp and three in 

 number in the dextral mandible and five in the sinistral. The 

 mandibles are always strongly chitinized and fitted for cutting 

 and grinding. They are so constructed that they interlock when 

 at rest. Asymmetry of various degrees exists between the dentes 

 and concavities. Aside from such differences, the mandibles are 

 similar in form on both sides and more or less similar in both 

 sexes. They usually differ, in different species, in size, shape, 

 and manner of interlocking, but most of the structures in the 



