136 THE CANADIAN liNTOMOLOGIST 



The dorsal and inner valvulae (outer and posterior gonapophyses) arise in 

 the same transverse plane across the middle of the sternum. The former are 

 subcylindrical and terminate in well-developed styli like those of the male, which 

 reach just beyond the tips of the paraprocts, and are about half as long as the 

 valvula itself. The apices of the ventral valvulae reach to about the ends of 

 the dorsal valvulae, without the styli, and as the dorsal valves in the adult are 

 distinctly longer than the ventral valves, it is evident that the styli are not 

 cast off at ecdysis, but go to form the apices of the dorsal valves. 



The inner valvulae occupy the space between the outer or dorsal pair, and 

 are contiguous with the latter and with each other at base. They are simple, 

 styliform processes, falling a little short of the dorsal valvulae without the styli. 

 A comparison between the structure of the immature and mature ovi- 

 positor of Grylloblatta, and the remaining parts of the 9th sternum will be made 

 in my later paper. It may be mentioned here, however, that the lateral parts 

 of the 9th segment, shown in Fig. 10 (vf) become the small triangular plates 

 which Crampton has termed the 'Valvifers." 



Concluding Remarks. 

 It is not my intention to discuss here in detail the phylogenetic relations of 

 Grylloblatta, but attention may be drawn to a few points which have a bearing 

 on the problem. 



One of the most significant features possessed by the male is the remarkably 

 primitive structure of the 9th abdominal sternum. In no other Pterygote 

 insect, so far as I am aware, is there to be found an abdominal sternum con- 

 sisting of sternite and separate, undivided coxites, each bearing a simple stylus. 

 In some Ephemerids, such as Blasturus nebidosus, the 9th sternum of the male 

 consists of sternite and separate coxites with styli, but either the styli or the 

 apical part of the coxites are secondarily segmented, and even this condition 

 is unusual, as the coxites in the Ephemerida are generally united to form a 

 single plate. 



It is in the Thysanura that we find abdominal sterna most nearly compar- 

 able to the 9th sternum of the male Grylloblatta in respect of the features men- 

 tioned. In certain genera of Lepismoidea (Nicoletia and Atelura) the 9th 

 sternum of the female possesses, in addition to the stylus-bearing coxites (present 

 in both sexes), a sternite overlapping the bases of the coxites.^ In most of the 

 genera of this order and of the Machiloidea, however, the sternite is absent from 

 the 9th segment, but in the latter group the other abdominal sterna, or most of 

 them, show all these parts, although the coxites are separate from the sternite, 

 and basally from one another, only by sutures. 



In this connection it may be added that Grylloblatta is interesting as giving 

 additional support, if such be necessary, to the view that the lateral gonapo- 

 physes of the female are prolongations of the coxites of segment 9. 



Thus in the structure of the 9th sternum of the male, Grylloblatta is not 

 only more primitive than any other Orthopteroid insect, but also more so than 

 the Plecoptera, Embiidina and Dermaptera (together constituting the '"Pan- 

 plecoptera" of Crampton) in all of which the division into sternite and coxites, 

 and the styli, have been lost. It is also more primitive than any of the true 

 Orthoptera in the absence of a subgenital plate in the female other than the 

 5. Escherich, K., Das System der Lepismatiden, Zoologica, 1905, Bd. 18, Heft 43, p. 25. 



