1919] Walker: Structure of OrtJiopteroid Insects 299 



decidedly folded and irregular on the dorsal side and bilobed 

 at the apices, though ventrally smooth. There is a prominent 

 sub-basal process on the dorsal side (pvd) but it is unchitinized. 

 It is perhaps represented in the Mantids by a minute lateral 

 lobe, which is present in this situation. The expanded bases 

 are united behind by a narrow strip of chitin, in front of which, 

 closely connected with the bases, is the peculiarly shaped 

 superior intervalvula. There is also a pair of short spurs (sap) 

 which [may represent the superior apophyses (not present in all 

 Blattidae) and a pair of slender rods with thin, anterior expan- 

 sions, (iap), which surround the bases of the inner valves and 

 meet in a somewhat heavier median portion (iv), just behind 

 the ventral valve bases. These rods evidently represent the 

 inferior apophyses, while the thicker median piece is the inferior 

 intervalvula. The spermatheca opens a little behind this plate; 

 in other forms, such as Blatta, directly upon it. 



The inner valvulce have much the same form as in Stagmo- 

 mantis and as in this genus they are slender, close together, and 

 lie in the hollow of the dorsal valvule, close to the latter and 

 engage the ventral valvulae very feebly. In their slightly 

 expanded, flexible apices, the lack of a true intervalvular 

 membrane, and the presence of a pair of ventral basal lobes, 

 they also recall the Mantids. They are not fused with the 

 superior intervalvula, however, but are connected with the 

 latter by a peculiar ball and socket joint, the dorsal surface 

 of the fused valve bases bearing a knob, which fits into a socket 

 in the transverse part of the superior intervalvula. In front 

 of the knob the fused valve-bases form a thin plate which is 

 curved upwards (him). This plate is similar in position to 

 the plate (him) in Stagmomantis (Figs. 45, 49) and is doubtless 

 its homologue, as in Stagmomantis this plate is likewise con- 

 tinuous with the bases of the inner valvulae, as well as the 

 superior intervalvula, of which it appears to form a part. 



It will be seen from the foregoing description that, in spite 

 of wide differences in the form and proportions of the various 

 parts they are essentially similar in the Blattids and Mantids, 

 the differences being of small weight, as compared with the 

 many points of resemblance. 



In addition to the structures described, there is a rather 

 large, though ill-defined chitinized area behind the bases of the 

 dorsal valves (ca), and serving for the attachment of muscles. 



