BY R. J. TILLYARD. 421 



Besides development of the wings, there is a gradual develop- 

 ment of the abdomen, by elongation. The wings at their full 

 length are about 2-3 mm. longer than the undeveloped abdomen. 

 Later on the abdomen gradually becomes narrowed and elongated, 

 until it reaches some 5 mm. beyond the wings. The development 

 is somewhat slow, occupying about half-an-hour. 



The newly developed imago is a very colourless insect, the head 

 parts being greenish and transparent, with a bluish tinge above, 

 underside almost colourless. Thorax and abdomen colourless 

 below, pale greyish-blue above, the abdomen having rings of dark 

 purplish-red at the base of each segment. The only conspicuous 

 markings are a black spot near each wing-join; these afterwards 

 extend to form the dark lateral rays of the thorax. Some time 

 elapses before the true colouration of the insect becomes apparent. 

 For the first few days the brilliant blue colours of the mature 

 insect do not appear, but are replaced by a bright orange-pink, 

 somewhat similar to the colouration seen in Lestes analis. I 

 kept one specimen alive for nearly a week, and by that time only 

 the slightest bluish tinge was beginning to show itself. How- 

 ever, it is probable that in a state of nature, and especially with 

 abundant food, the blue colour would assert itself much earlier. 



Imago: The following is a description of the mature 

 insect : — £. Total length 37-40 mm.; abdomen 30-31 mm.; wings, 

 fore 21 mm., hind 20 mm. 



Wings: Neuration black; pterostigma almost black, oblong, 

 1*5 mm. Nodal Indicator \ 2 9-10 



1 2 8-10 



Head: Eyes violet-blue above, whitish below; ocelli black, in 

 a triangle; antennce black, basal joint somewhat swollen. Post- 

 clypeus jet-black; anteclypeus bright blue. Labrum bronzy- 

 black, slightly bluish at sides; labium, whitish, bordered with 

 black along the outer edge; mandibles pale dirty brownish. 



Thorax: Prothorax black above, paler beneath. Meso- and 

 metathorax deep bronzy-black, with a narrow light blue dorsal 

 ridge and three broad bright blue bands on either side, the first 



