1919] Walker: Structure of Orthopteroid Insects 295 



segments, so that they are separated from their sterna by a 

 wider extent of pleural membrane. The tenth tergite is also 

 laterally reduced, but is prolonged backwards over the supra- 

 anal plate, taking the place of the latter, which is greatly 

 reduced and feebly chitinized, as are also the larger paraprocts. 

 The spiracles are all situated on the tergites, near their lateral 

 margin. The cerci consist of about 15 short segments, which 

 are but little flattened. 



The ovipositor is of considerable size, but almost entirely 

 concealed by a huge hood-like structure, which is the seventh 

 sternum and is therefore not the homologue of the subgenital 

 plate of the groups thus far discussed. Under cover of this hood 

 and adherent to it is a bifid plate (Fig. 44), which overlaps the 

 vulva. This is part of the eighth sternum and apparently the 

 homologue of the subgenital plate of the Orthoptera and Phas- 

 moidea. The vulva lies between a pair of median shelf-hke valves. 

 Extending forward from between the base of the valves is a 

 thick fold with a chitinized edge (ar), upon which is a small 

 opening of the spermatheca. In the natural position of the 

 parts this orifice lies just above the vulva. The valvulae are large, 

 but of irregular shape and only partly chitinized. The dorsal 

 pair overlaps the ventral and both are distally decurved and 

 peculiarly lobed at their blunt apices. The ventral valvulse 

 are widely separated for some distance from their bases, this 

 space apparently serving for the exit of the ova and secretions 

 which form the ootheca. The basivalvulas are usually distinct 

 and heavily chitinized, being the firmest parts of the valvulae. 

 Just above the basivalvula is a small, but well-chitinized valvifer 

 connecting the dorsal and ventral valvulas in the usual way. In 

 Crampton's figure of the ovipositor of Stagniomantis^^ this plate 

 is incorrectly labeled "basivalvula" (i. e., of the dorsal valvulae). 

 It bears only one apodeme, parallel to the antero-ventral margin 

 and continued as a strong ridge across the pleural membrane 

 to the tergites of segments eight and nine, opposite the inter- 

 segmental groove, where it is expanded into a short broad 

 spur (pap), and is thence continuous with the short tergal 

 apodemes of these two segments. (Fig. 48). The pleural 

 apodeme is a thickening of the intersegmental furrow, and is 

 marked externally by a distinct groove. 



13 Jour. N. Y. Ent. Soc, Vol. XXV, PL XVI, Fig. 7, 1917. 



