INDIAN DRAGONFLIES. 603 



38. Diplacodes trivialis, Karsch, Ent. Nach. 17, p. 246. (1891). Sumatra. 



Kirby, Ann. Mag. Nat. Hist. (7). 15. p. 271. (1905). 

 Lihellula braminea, Fabr. Suppl. Ent. Syst. p. 284. (1798). 

 Idhellula trivialis, Ramb. Neor. p. 115. 1842. 

 Diplax trivialis, Brauer. Novara. p. 104, 1866. Batavia. 



Id., Zool. hot. Wien. 17, p. 289, 1867. New Guinea. 

 Trithemis trivialis, Kirby. Trans. Zool. Soc. Lond. 12, p. 278. (1889). 

 Id. Cat. p. 18, 1890. 

 Expanse 45 mm. Length 26 mm. 



Male and female very similar. 



Head ; eyes very pale blue, capped above with a small greenish zone which 

 shows brown in certain lights ; vesicle pale blue or tinged with yellowish green ; 

 occiput brown; forehead, epistome, labrum and labium very pale blue. A 

 black, basal line to the forehead in front of the vesicle. 



Prothorax pale greenish yellow with the humeral stripe of the thorax continu- 

 ed on to it. 



Thorax the same colour but fading to pale blue on the sides and almost to 

 white on the underneath. A brownish humeral strijje, finely bordered on the 

 inner and outer sides with black. Laterally, tl^e sutures finely mapped out in 

 black and often a small black spot lying between them. 



Legs greenish yellow, the femorae ringed with black at the distal ends ; flexor 

 surfaces of the tibise black. 



Wings hyaline, with a small basal, saffronated spot in the hind wings, more 

 noticeable in the female and extending out as far as the cubital nervure, not 

 quite to the inner border of the loop and about half-way or less to the tornus ; 

 Ih antecubital nervures ; stigma pale brown ; membrane grey ; costa yellow. 



Abdomen black, marked variably w'ith pale, greenish-yellow, the first 3 seg- 

 ments with broad spots on the sides which almost obscure the ground colour, 

 the sutures on these 3 mapped out finely in black ; long, narrow, oval spots on 

 the 4th to 7th segments, the distal 3 entirely black. (In the female and juve- 

 nile males, these last 3 segments bear small, similar spots to those on the 4th 

 to 7th). Beneath, pale blue. 



Very adult specimens of the male tend to lose most or all of the yellow mark- 

 ings, the abdomen especially, being entirely black with a frosting of blue. In 

 some specimens which I took on the Katraj Lake, Poona, the frosting extended 

 over the whole of the thorax, legs and abdomen and the markings were entirely 

 obsolete. In these specimens the eyes were a beautiful topaz blue and the 

 stigma in all wings was a light azure blue. 



Sexual organs of the male ; lamina moderately large and projecting and split 

 by a deep, broad, triangular cleft into 2 somewhat diverging lobes ; external 

 tentaculse broadly triangular ; internal small but robust and shaped as an 

 outwardly bent hook. Lobe projecting rather more than the tentaculee. 



Anal appendages pale yelloAv. 



D. trivialis is a species of the plains and usually frequents low, dry situations. 

 Numbers may often be seen settling or hovering over roadsides and bye-paths 

 or bare waste lands. It is comparatively rarely seen over water and then onl}' 

 at certain seasons when very adult specimens appear to betake themselves to 

 the neighbourhood of lakes and tanks for purposes of breeding. In this respect 

 it contrasts strikingly with nebulosa which is rarely seen away from water. 



In Madras where both species are moderately common, the two are rarely 

 taken in company. 



Hab. The whole of Continental India except in the hilly regions. Ceylon, 

 Singapore, Java, New Guinea, Lower MesojKJtamia. 



