Atislralian Ternule, MasioLcnucs daru/tucntus. 145 



the Protoblattodea (wliicli he considers as the forms ancestral 

 to the cockroaches, termites, etc.) from Plaeodictyopterous 

 forebears, while I am incUned to consider the Plecoptera 

 as more closely related to the forms givin*^ rise to the ter- 

 mites and their allies which constitute the superorder 

 Panisoptera {i. e. the Protoblattodea, Blattodea, Mantodea, 

 Isoptera, Zorapteja, etc.). The evidence for the grouping 

 given above, will be presented in a series of articles (of 

 which the present paper is one) dealing with the external 

 anatomy of the head, thoracic and terminal abdominal 

 regions of the insects in question. 



Explanation of Plate JV. 



Fig. 1. — Lateral view of terminal abdominal structures of alate 



female of Mastotermes darwinensis Froggatt. 

 Fig. 2. — Lateral view of terminal structures of alate male of same. 

 Fig. 3. — Ventral view of terminal structure of alate female of 



Fig. 4. — Ventral view of terminal structures of alate male of same. 



ABBREVIATIONS 



In all figures, the letter " t " affixed to the numerals denotes 

 the tergal plate of the segment indicated by the numerals, while 

 the letter " s " denotes the corresponding sternal plate of the 

 segment in question. 



c = cerci, or their point of attachment. 



dv = dorsal valvulae of ovipositor, composed of tlie styli and 



their basal portions, 

 ha = hypandrium, or stmnite below the genital a})j)aratus of 



the male. It is usually formed by the sternite of the 



ninth abdominal segment, 

 hg — hypogynium, or sternite below the genital apparatus of 



the female. It is usually formed by the sternite of the 



seventh or eighth abdominal segment, 

 iv — intermediate valvulae of the ovipositor. 

 pa =: paraprocts, or cerci-bearing plates of the eleventh segment 



of the abdomen. 

 s — styli. 



sg = styligers, or coxites, the basal structures bearing the styli. 

 vv == ventral valvulae of the ovipositor, or appendages of the 



sternite of the eighth abdominal segment. 

 TKANS. ENT. SOG. LOND. J<J20. — PARTS I, II. (JULY) L 



