n] 



EXTERNAL FEATURES AND SKELETON 



33 



positions of appendages and vestigial structures are indicated in 

 the diagram (fig. 12 A). 



The function of the anal appendages in the male is to grasp the 

 female firmly during pairing. In the Anisoptera, the inferior 

 appendage is always pressed down upon the occiput of the female, 



s.up 



Fig. 12. Diagram to shew the position of the anal appendages of the male, viewed 

 from behind. A in Anisoptera, B in Zygoptera. a anus ; inf inferior appendage ; 

 la lamina supra-analis ; la' laminae sub-anales ; st i:l bipartite eleventh sternite ; 

 sup superior appendages; t n eleventh tergite. Original. 



while the superior appendages become engaged between the pro- 

 thorax and the back of the head, and most usually press forward 

 against the latter. Thus the head is held as it were between the 

 jaws of a vice (fig. 13 A). In the Petalurinae, however, the broad 

 leaf-like superior appendages (fig. 13 B) fit closely upon the mesepi- 

 sterna, while the wide inferior appendage, placed upon the occiput, 

 presses the head back so as to hold the superiors in position. In 

 a number of forms with long or forcipate superior appendages, a 

 similar kind of grip seems to be 

 the rule, though undoubtedly the 

 chief pressure is on the head. 

 In the Gomphinae the inferior 

 appendage is strongly bifid, en- 

 gaging the broad occiput in two 

 depressions; while the superiors, 

 which are too short to be of much 

 direct use, are generally held in 

 place by tubercles or other out- 

 growths from the back of the 

 occiput. In the Petaliini (fig. 14) 

 the inferior appendage is trifid 

 and very long ; the superiors very 



short. The method of pairing has not yet been observed. 

 T. D.-F. 



A 



Fig. 13. Position of the anal ap- 

 pendages of the male in Anisoptera 

 during pairing. A in Aeschna, B in 

 Petalura. e eye; inf inferior ap- 

 pendage ; ml mesostigmatic lamina ; 

 sup superior appendages ; 810 ab- 

 dominal segments. A from E. M. 

 Walker, B original. 



