260 HACHIRO YUASA 



coilae are always present and distinct. They are not well differ- 

 entiated in Diapheromera, but are prominent mesocaudal pro- 

 jections in Tettix. 



The maxillariae {my) in Blatta (fig. 23) are narrow plates sur- 

 rounding the lateral and caudal margins of the occipital foramen. 

 The ectal surface of each maxillaria is closely applied to the 

 ectal surface of the postgena and the occiput. The lateral mar- 

 gins are folded, forming a roll. The caudal part of each roll is 

 produced into a cone-shaped projection, an odontoidea {od). 

 The microcoria {ma) is attached to the ventral margin of the 

 maxillariae. The caudal side of each maxillaria is reduced to a 

 narrow band, the cephalic part of each lateral portion is expanded 

 and produced to form a distinct paracoila, and the cephalomes'al 

 margin is fused with the corpotentorium. The maxillariae are 

 simple in Orchelimum, Melanoplus, and Tettix. In other gen- 

 era they vary in size and shape, are very complicated and have, 

 besides odontoideae, many projections, some of which bear ten- 

 dons (figs. 27 and 31). 



The odontoideae {od) are not well differentiated in Orcheli- 

 mum and Melanoplus, but are distinct in the other genera. In 

 Blatta, Stenopelmatus, and Anisolabis they occur on the caudal 

 third of the lateral parts of the maxillariae; in other genera near 

 the cephalic part of the maxillariae and extend ventrad or caudo- 

 ventrad of the corpotentorium. 



The clypeus (c) in Blatta (fig. 1) is the convex sclerite attached 

 to the cephalic margin of the front. The caudolateral angles are 

 produced into thickened, transverse lobes, and each bears a dis- 

 tinct precoila. The lateral margins are rounded and the ce- 

 phalic boundary is the distinct clypeolabral suture. The clypeus 

 is transverse, the lateral margins are entire and converge cephalad. 

 In Gryllus (fig. 5) and Melanoplus (fig. 10) there are oblique 

 furrows extending from the middle of the lateral margins, which 

 may represent the incomplete clypeal suture {cs) dividing the 

 clypeus into preclypeus and postclypeus. In Diapheromera (fig. 

 8) the mesal part of the clypeus is dilated and produced, forming 

 a prominent elevation. 



