JKHI] COLORATION 255 



two-thirds of the wing is of a glorious metallic blue colour. This 

 latter species has forsaken still waters, and competes with the 

 gaudy Calopterygidae upon the broad flowing rivers of Papua and 

 North Queensland. 



3. The Caloplerygidae. This family, so well named the 

 "beautiful- winged" Dragonflies, shews us the development of 

 metallic coloration carried to perfection. The colours are 

 practically confined to the males alone. These are, indeed, the 

 Birds of Paradise amongst Odonata. In a number of forms, e.g. 

 Anisopleura, Diphlebia, only black pigment is laid down. In the 

 beautiful genus Hetaerina and its allies, a lovely transparent red 

 pigment (apparently the same as in the Petaliini) more or less 

 overspreads the wing. In a few forms (e.g. Diphlebia lestmdes] 

 a transverse milky-white band appears (cf . Tholymis in the Libellu- 

 linae). In advance of these, we note the glorious effect of the 

 superimposed interference coloration in such cases as Pseudophaea, 

 Matronoides and Neurobasis (PI. I, figs. 6, 7), where either part 

 or all of the pigmented portion of the wing scintillates in radiant 

 blue or green. Finally, in Rhinocypha (PI. I, figs. 4, 5) the play 

 of metallic colours, in a combination of flashing reds, mauves, 

 purples, bronzes and greens, utterly baffles description. The 

 .development of small clear areas or "windows" in such a wing as 

 that of R. quadrimaculata, or R. fenestrella, only serves to heighten 

 the effect of these radiant rainbow hues. 



Larval Coloration and Colour Changes. 



The coloration of Odonate larvae is very uniform, but may 

 be divided into two classes : (a) those shewing no definite pattern, 

 (6) those with a pattern. All larvae which live hidden in sand or 

 mud, or under debris, need no colour-pattern, and most of them 

 have none. The few that have owe it apparently to the fact that 

 they have only recently taken to hiding away. Larvae that live 

 either on the river bottom, or amongst water-weed, shew a definite 

 pattern, which helps to render them inconspicuous to enemies and 

 prey alike. In bottom-dwellers, the pattern is a beautiful mottling 

 of pale brown or straw with dark brown or olive (e.g. most 

 Eucorduliini and Libettulinae) In weed-dwellers, a ground colour 

 of semi-transparent green, yellow, or olive, is overlaid with darker 



