1919] Walker: Structure of Orthopteroid Insects 291 



The fact that the valvifers are well chitinized and bear the 

 usual ridges for rnuscular attachment seems to indicate, how- 

 ever, that the muscles in question are probably present and yet 

 no sclerite for their inner attachment was found, unless it be 

 the bilobed prominence. As compared with Ceuthophilus 

 this prominence would appear to belong to the pons, but in 

 any case it seems probable that the pons was primitively not 

 distinct from the superior intervalvula, as is indeed the case 

 in such forms as the Mantids where no distinct intervalvular 

 membrane is developed. With the great development of this 

 membrane in the Tettigoniidas, however, the pons became 

 differentiated, retaining its connection with the superior 

 intervalvula in some forms (e. g., Tettigonia) while becoming 

 entirely separated from it in others, such as Ceuthophilus. 

 Although the matter requires further investigation, it may be 

 considered probable that the superior intervalvula is at least 

 partly represented by the bilobed prominence beneath the 

 pons. If this is the case, Grylloblatta differs from all the other 

 forms studied in which the superior intervalvula is present in 

 that this sclerite does not connect the bases of the dorsal 

 valvules, but lies beneath them. 



The rami of the inner valvule are fused with the inferior 

 apophyses which, as stated above, is not distinct from the 

 inferior intervalvula. This firm union of the dorsal and inner 

 valves, together with the manner in which the latter fit closely 

 within the former, would seem to prohibit any independent 

 movements of the inner valvulae. 



A short distance behind the united inferior apophyses is 

 the opening of the receptaculum seminis, a small, thick-walled 

 rounded pouch. 



The female nymph — (Figs. 36-38). The only known speci- 

 men of the female nymph was recently described by the writer 

 ('19)^^ and is nearly full grown. The eighth sternum is similar 

 to that of the adult, except that it is uniformly, though feebly, 

 chitinized. The ventral valvulas arise just behind the sternal 

 margin and are straight, subcylindrical processes, bluntly 

 pointed at the apices. The basivalvulae are clearly defined by 

 a transverse groove. The sternal region of segment nine still 

 has its primitive horizontal position in line with that of segment 



18 Walker, E. M., Can. Ent., Vol. LI, 11. pp. 131-139. 1919. 



