THE CANADIAN ENTOMOLOGIST 135 



The 9th segment (Fig. 5) is relatively much smaller than in the adult. 

 Its sternal region is clearly di\i(led into sternite and stylus-bearing coxites. 

 The asymmetry is noticeable but far less marked than in the adult, the base 

 of the left coxite being only about 1.5 times as broad as that of the right. Both 

 are ventral in position and triangular in form, with relatively large styli. There 

 is as yet no indication of the spur borne by the right coxite in the adult. 



The 10th segment is relatively larger than in the adult and consists chiefly 

 of the tergite, which forms a ring broken only by a small sternal area (st lOj. 

 The latter is quite distinct but membranous. There is as yet no distinct ap- 

 pearance of asymmetry in the 10th segment. 



In the intersternal membrane between segs. 9 and 10 two slight ventro- lateral 

 raised areas are visible, the rudiments of the two lobes of the phallus (Fig. 10). 



The cerci are quite similar to those of the adult except that they are relatively 

 stouter, and the constriction between the first two joints is less clearly defined. 



The supra-anal plate and the paraprocts are much more prominent than 

 in the adult, the form.er being slightly chitinized above, the latter membranous 

 but pubescent. 



The two specim.ens belonging to the older nymphal stage (stage B) measure 

 11 mm. and 12.5 mm., respectively, the abdomen of the former being con- 

 tracted. The hind tibiae in each are about 3.1 mm. long, and measurements 

 of other parts are also closely comparable. The form of the 9th sternum has 

 changed very little from stage A, though the asymmetry of the coxites is a trifle 

 more marked. The principal change is the greater contrast in size between seg- 

 m.ents 9 and 10. The former is relatively considerably larger, the latter smaller 

 and almost entirely concealed in a direct ventral view (Fig. 6). The ventral 

 edges of the 10th tergite nearly meet one another, there being no longer a dis- 

 tinct 10th sternum. The supra-anal plate and paraprocts are also greatly 

 reduced, almost as much so as in the adult. 



Owing to the increased depth of segment 9, the intersegmental membrane 

 on which the phallus develops is now nearly vertical instead of horizontal in 

 position. The two lobes of the phallus (Fig. 7) are much larger, asymmetrical 

 and separated by a fissure having a obliquity similar to that of the adult but less 

 marked. No chitinized areas are as yet present. 



The difiference in size between these two nymphal stages is so slight that 

 it is almost certain that they represent successive instars. 



The Female Nymph. 

 Th-e single immature female is somewhat larger than any of the male nymphs, 

 measuring 15 mm. in length, the hind tibiae 3.25 mm. The antennae have 24 

 to 25 segments. The 8th abdominal sternum is similar to that of the adult, 

 except that it lacks the pale median area present in the latter, and is less firmly 

 chitinized. The ventral valv^es of the ovipositor or valvulae (anterior gona- 

 pophyses) arise from the hind margin of the 8th sternum and extend back a 

 little beyond the hind margin of seg. 10. They are straight, subcylindrical, 

 broadest at base, and taper to bluntly pointed apices. The basal segments 

 (basivalvulae) are well marked off by a distinct constriction. The sternal 

 region of seg. 9 is clearly defined and still has its primitive horizontal position, 

 in line with that of seg. 10; whereas in the adult it becomes vertical, so that the 

 bases of the dorsal and inner valvulae are directly above those of the ventral 

 valvulee (not including the basivalvulae). 



