36 



THE IMAGO 



[CH. 



2. Zygoptera. The males have a pair of superior appendages 

 (sup) homologous with those of the Anisoptera. Likewise, these 

 also form the anal appendages of the female, which are usually 

 extremely reduced cylindrical or conical stumps. The inferior 

 appendages of the Zygoptera are, however, two in number, and 

 have nothing in common with the so-called "inferior appendage" 

 of the Anisoptera. They lie latero-ventrally below the anus, one 

 on either side, and represent the cerci of the larva ; that is, they 

 are outgrowths from the reduced bipartite sternite of the eleventh 

 segment. The laminae anales are placed as in the Anisoptera. 

 The female, as in the Anisoptera, has no inferior appendages, 

 though Heymons has shewn the existence of their rudiments in 

 Calopteryx. The diagram, fig. 12 B, shews the positions of the 

 various parts. 



Fig. 16. Position of the anal appendages of the male in Zygoptera during pairing. 

 A in Austrolestes analis Ramb., B in Pseudagrion aureofrons Tillyard. a ante- 

 rior; b median; c posterior lobe of prothorax; cx 1 procoxa; cx 2 mesocoxa; 

 h hook; inf inferior appendages; ml mesostigmatic lamina; sup superior 

 appendages; 9-10 abdominal segments. Original. 



In the Zygoptera, during the process of pairing (fig. 16), the 

 appendages of the male engage the prothorax and the back of the 

 head of the female, in quite a different manner from that described 

 for the Anisoptera. In this case it is the hind lobe of the pronotum 

 which becomes engaged between the jaws of the vice, the head only 

 being touched when the inferior appendages are long enough to 

 pass forward and press against it from behind (as in some Lestinae). 

 If the superior appendages are forcipate, a simple transverse lock- 

 grip (fig. 16 A) behind the pronotum appears sufficient to hold the 

 female, bearing in mind the fact that the latter always assists by 

 pressing the pronotum backwards against the spiracular dorsum. 



