446 ON THE GENUS NANNODYTHEM1S, 



beginnings of a fourth side in one or two specimens. This 

 extreme variability of the hindwing triangle causes it to lose 

 absolutely its generic value, and the only course open to us is to 

 suppress Nannodythemis Brauer, in favour of the older genus 

 Nannophya Rambur. If the name Nannodythemis is to be retained 

 at all, it must be used only as indicating a geographical subgroup 

 of the principal genus Nannophya, to include the three Austra- 

 lian species which are so closely allied. And in this sense only 

 I will retain the name in this paper, as I prefer that Dr. Ris 

 should deal more fully with the two names in his great work on 

 the " Libellulines " which will shortly be published..* 



I propose to name the Western Australian form N. occidentalism 

 and to give to the third species (that from Wentworth Falls) the 

 name of N. Dalei in memory of de Selys' great friend, the well- 

 known British entomologist Mr. Dale; this name having already 

 been applied by de Selys to this species on the label in his cabinet. 

 In order to understand fully the differences between these three 

 closely allied species, I will include a careful description of N. 

 ausiralis Br., taken from my own series. 



1. N. australis Brauer. (Plate vi. fig. 1). 



(J. Total length 20-21 mm.; abdomen 13-13-5 mm.; forewing 

 14-14-5, hindwing 13-5-14 mm. Wings well rounded, neuration 

 black, bases very slightly or not at all saffroned in mature speci- 

 mens; in some less mature specimens there is saffroning up to 

 arculus of forewing and from base to behind nodus of hindwing. 

 Pterostigma 1 mm., dark brown between the black nervures, 

 outer portion just whitish. Sectors of arculus arising together 

 at or near its base. Triangle of forewings abnormal, the two 

 portions of the upper side being practically equal; triangle of 



* I have to thank Dr. Kis for showing me the generic difference; I myself 

 did not possess the published definitions of the two genera until recently. 

 Hence while I must put on record the two new species for inclusion in 

 Dr. Ris' great work, I feel I should leave the full discussion of the generic 

 differences to him who first discovered them. 



