1922] Walker: Structure of Orthopteroid Insects 37 



On this part we find the genitalia, so that it must be considered 

 as belonging properly to the intersternal membrane between 

 segments 9 and 10, although it underlies the 9th tergum. 



This area in its distal part may be more or less chitinized 

 (the "post-sternite" of Crampton) or may bear a projecting 

 plate, the subanal vomer ("vomer sous-anal" of Pantel), (Fig. 

 71, vo). Pantel considered the vomer to belong to the 10th 

 sternum, but it appears to me to arise from the membrane 

 just in front of this segment. 



The elongation of the 9th tergum without a corresponding 

 development of the true sternum has a parallel in the Odonata, 

 in which the genitalia likewise have the appearance of belonging 

 to the sternum itself, rather than the intersternal membrane. 



The large size of the 10th sternum is likewise probably due 

 to secondary elongation of the segment, and the primitive 

 10th sternum may be almost entirely absorbed in the bases of 

 the paraprocts (vide p). Sometimes the cleft between the 

 paraprocts is continued cephalad as a more or less distinct 

 groove almost or quite to the base of the 10th sternal region. 



The male genitalia of the Phasmoidea form an irregular, 

 asymmetrical mass, suggestive in a general way of the Blat- 

 toidea, Mantoidea and Grylloblattoidea. I have studied the 

 male genitalia of only two species, Diapheromera femorata Say 

 and Aiiisomorpha huprestoides (Stoll.). 



In the former (Figs. 74, 75) the genitalia form a prominent, 

 asymmetrical structure slightly divided, especially on the 

 ventral face, by an oblique groove, on the left side of which the 

 ejaculatory duct opens. This duct is directed slightly dextrad, 

 and opens directly on the ventral surface, there being no 

 invaginated pouch as in the Orthoptera, and no virga. The 

 dorsal surface of the genitalia is covered by a chitinous plate 

 (dpi) from which a blunt cornu (possibly the paramere) arises 

 on the left side (pm?). There is no such process on the right 

 side, but on the postero-ventral surface, next to the median 

 groove, there is a pair of plates, which apparently form a sort 

 of clasper (cl), and from which an apophysis (ap) for the 

 attachment of muscles projects inwards. The presence of 

 this clasper on the left side is suggestive of the Mantids, certain 

 Blattids and Grylloblatta. The left lobe is ventrally thin- 

 walled, a feature which is also somewhat suggestive of 

 Grylloblatta. 



