1922] Walker: Structure of Orthopteroid Insects 39 



Grylloblattoidea. 



The sole member of this order is Grylloblatta campodeiformis 

 Walk., the male genitalia of which have been described in 

 detail by the writer ('19). 



In the adult male the ninth segment, particularly the 

 sternum, is large, while the tenth is small, though prominent. 

 The intersternal area on which the genitalia are situated is thus 

 vertical, as in the Orthoptera, Blattoidea and Mantoidea. 



Viewed from above (Fig. 62) the terminal segments appear 

 symmetrical or nearly so, but from below (Fig. 63) or behind 

 (Fig. 64) a pronounced degree of asymmetry is apparent. This 

 asymmetry involves the ninth sternum, the tenth tergite and 

 the genitalia. 



The ninth sternum is remarkable for the retention of the 

 primitive division into sternite and coxites. The sternite is of 

 about the same size and form as the tergite, from which it is 

 separated only by a suture. It is nearly symmetrical, although 

 the left side is slightly shorter than the right. The coxites, 

 although of equal length, are very different in size and form. 

 The left coxite is broadly triangular and strongly convex. 

 Its base extends from the tergo-sternal suture to a point well 

 to the left of the middle line. The right coxite is confined to 

 the right side, having a much narrow^er base. It is also tri- 

 angular, but bears a strong spur from its upper margin, directed 

 meso-caudo-dorsad. Both coxites are moveably articulated 

 with the sternite and bear well-developed styli upon their 

 apices. 



The tenth tergum is narrowed beyond the bases of the cerci 

 to a truncated apex, but does not form a freely projecting plate. 

 It is continued ventrad around the bases of the cerci, terminating 

 below in a pair of free, unequal arms, which nearly meet one 

 another in the middle line. The left arm is the longer and is 

 wholly chitinized, except at the apex, which is slightly expanded 

 into a little disc or pad. The right arm is chitinized only at the 

 base and is without the terminal pad. It has the appearance 

 of a functionless structure. The tenth sternum is obsolete 

 in the adult. 



The cerci are exactly like those of the female, being long and 

 cylindrical and divided into eight distinct segments. There is 

 a small, ventro-mesial, cereal basipodite. The supra-anal 



