BY R. J. TILLYARD. 453 



Hah. — Cooktown, N. Queensland; taken by myself, De- 

 cember, 1907, and January, 1908. Banks' Island, Torres 

 Straits (H. Elgner) ; February, 1910. 



Types: cf $ , Coll. Tillyard. 



This species was found flying on a small billabong or back- 

 water of the Annam River, in company with rrosagrion 

 pruinescens (see below). The two species are very similar 

 in habits, but easily separated at a glance while flying, 

 owing to their very different colouration. The males of /. 

 torresiana shew no signs of pruinescence, and their blue parts 

 ■ are conspicuous ; the females appear very similar to the 

 males. On the other hand, the pruinescence of the males of 

 Frosayrion prumescens is very noticeable, while the orange 

 females of that species are very distinct. /. torresiana is 

 very closely related to /. heterosticta Burm., to which it 

 seems to bear exactly the same relationship that A usfrolesfes 

 insularis does to A. analis Bamb. 



24. IsCHNURA PRUINESCENS Tillyard. 



Agriocnemis prtiinescens Tillyard, loc. cit. 1906, p.l91(J' only); 

 loc. cit. 1907, p.385((J$). 



In spite of the position of the second antenodal in this species 

 (placed well before the arculus), it seems inadvisable to separate 

 it from its evidently close allies, Ischmira heterosticta Burm., and 

 /. senegalensis Ramb., which it resembles in every other character 

 of the genus except the one mentioned. Dr. Ris informs me that 

 he has examined many species of Ischnura, from all parts of the 

 world, and, in many species, he has found "slight degrees of pro- 

 cession of the arculus distally from the second antenodal cross- 

 vein to be a common variety all over the genus." This species 

 may, however, be fairly considered to be a link in the chain con- 

 necting the more typical Ischnura species with Agriocnemis. 

 These two genera are closely allied, and are remarkable in both 

 possessing dimorphic female forms. The peculiar Ischnura-iorm 

 of the male appendages can also be traced down into Agriociiemis 

 (see Agr. hyacinthus, Plate xlviii., fig. 16). 



