BY R. J. TILLYARD. 715 



The following are the chief differences between the new species 

 and N. eludens Tillyard: — N. risi is considerably larger (hindwing 

 of ^ 22-5 as against 18-5 mm. in N. eludens); the pterostigma is 

 considerably larger (1-8 against 14 mm.) ; the vertex is pale yellow 

 (brown in N. eludens). The thoracic pattern is much bolder and 

 more intricate in N. risi, the bands being black, while those of N. 

 eludens are brown, and the second and third bands of the sides 

 practically joining in two places so as to isolate a large yellow 

 oval spot, whereas in N. eludens these bands are short and sepa- 

 rated (Figs. 7-8). The number of yellow spots, and bands on the 

 abdomen is much greater in N. risi than in N. eludens, there being 

 two yellow areas on each of segments 4-8 in N. risi ^, while JV. 

 eludens $ has one only on 4-G and none on 7-8 (Figs. 5-6). The 

 anal appendages of the males of the two species are very different; 

 those of iV. risi being long, straight, and parallel when seen from 

 above, while those of N. eludens appear short and incurved, almost 

 forcipate; seen in profile, the differences are quite as striking 

 (Plate Ixxiv., figs. 9-1 2). The genitalia of segment 2 of the male 

 are not quite similar, the hamule being more prominent in N. 

 eludens {Plate Ixxiv., Figs. 14-15). 



There is, besides, a well-marked difference in flight and habits. 

 N. risi flies very swiftly in and out along the edges of the creeks 

 and rivers, while N. eludens indulges in fantastic gyrations and 

 evolutions, often rising in a complicated spiral to settle high up on 

 a near-by tree. I did not notice this habit in N. risi, though I 

 watched carefully for it. In resting also, N. eludens depresses its 

 wings much more than N. risi does. 



In my opinion, it is impossible to consider these two species as 

 parts of one geographical whole, because their areas of distribu- 

 tion overlap, both being found in North Queensland in the same 

 localities. N. eludens is on the wing from January to May, while 

 A'', risi is only represented in December and January by a few old 

 and battered females. I have no doubt that males of iT. risi could 

 be taken in North Queensland by collecting in September or 

 October, the latter of which is the month during which it appears 

 further south. The supposition that they might be two broods 



