298 Annals Entomological Society of America [Vol. XII, 



• The ventral valvulae, like those of the Mantids, are irregular, 

 only partly chitinized and spread apart towards their bases. 

 But here a strange modification is seen. The bases are suddenly 

 enormously expanded and connected with one another by an 

 arcuate, chitinous band, which narrows at the sides and, 

 passing around behind the base, joins a broader plate in this 

 situation. This arcuate band, or its equivalent, varies greatly 

 in form in different Blattids and is clearly the homologue of 

 the transverse sclerite (ar) or chitinous edge of the fold in the 

 Mantids which bears the opening of the spermatheca. It 

 appears to be a special characteristic of these two nearly allied 

 orders. The posterior plates referred to are the basivalvulae, 

 which have reached this position by the spreading apart of the 

 bases accompanied by an outward rotation. A similar shifting 

 of the valve bases is noticeable in the Mantidas, but is much less 

 pronounced. In the immature Parcohlatta, up to the last instar, 

 no such peculiarities are seen, the ventral valvulse being close 

 together with typical basivalvulae, and this simple condition is 

 retained in the adult of Cryptocercus punctulatus Scudd. (Fig. 59) , 

 the ovipositor in this form having been apparently arrested in 

 development, in a manner closely comparable to that of the 

 Phasmid Timema calif ornica (see pp. 292-3). 



Immediately behind each basivalvula is the large valvifer, 

 which, as usual, connects the bases of the dorsal and ventral 

 valvulae and is continuous at its antero-lateral angle with a strong 

 apodeme, which follows the constriction between segments 

 eight and nine to the tergal margins of these segments and is 

 in every way comparable to the similar apodeme in the Mantids, 

 The valvifer is thus widely separated from the tergal margins 

 by a membranous area, which is crossed by the intersegmental 

 apodeme, their relations being essentially the same as in the 

 Mantidae, and but little different from those which are typical 

 of the Orthoptera, in which the ninth tergal apodeme is really 

 the homologue of the intersegmental apodeme. The longi- 

 tudinal groove of the apodeme is plainly seen and marks the 

 constriction between the two segments. 



Between the valvifers are two large plates which are con- 

 tinuous with the shafts of the dorsal valvulae, from which they 

 are strongly bent outwards and downwards. These are simply 

 the bases of the dorsal valvulae, and are not unlike the expanded 

 bases of these structures in Gryllus. The dorsal valvulae are 



