INDIAN DRAGONFLIES. 



255 



split into two leaf-like, triangular processes ; 9tli ventral plate prolonged as 

 a tongue-like process, extending to the end of the 10th segment. This 

 process strongly carinated and furnished at its base with two small hooks, 



Eab. — Throughout India, Ceylon, Burma, Thibet, Indo-Malaysia and 

 Indo-China. 



This insect is one of our few night-flying dragonfiies. Occasionally it 

 may be seen flying in the day-time in shady groves or dark jungles, but 

 usually it prefers to wait for sundown, at which time it quite suddenly 

 appears in great numbers, flying low over water. Of great interest is the 

 opalesceno patch on the hindwings of the male which serves the purpose of 

 a recognition mark for the females. After it has become too dark to 

 distinguish the insect, the pale, lambent glow of this patch may be seen 

 flitting like a Will-o-the-Wisp over the surface of the waters, where the 

 insect is busily engaged hunting mosquitoes, whilst keeping one eye open 

 for a chance female. 



Genus — Zyxomma, Rambur. 



Zyxomma, Eambur, Neur. pp 26, 30 (1842)— Hagen, Stett, Ent. Ztg., 

 10, p. 171 (1849)— Brauer, Zool. bot. A^'ien. 18, pp. 364 712 

 (1868)— Kirby, Trans. Zool. Soc. Lond. 12, pp. 258, 301 ,889) 

 — Foerster, Kahr. Mannheim, 71-72 (p. 3 sep.) (1906). 



Fig. 59. — Wings of male Zyxomma jjetiolatum showing neuration (x3). 



Head relatively large and globular, eyes contiguous for a very long 

 distance and resembling those of an Anax, occiput very small, vesicle 

 rounded above and overhanging the central ocellus so that this is invisible 

 when viewed from above, forehead prominent and deeply notched in 

 front of the ocellus, as if to give a free field of vision to the latter. 



Prothorax slightly arched, very small, its posterior lobe fringed with 

 short hairs. 



Thorax small, cubical, short, coated thickly with short hairs. 



Legs : hind femora with a row of verj^ small, closely-set spines and one 

 much larger spine at the distal end, mid femora with similar armature, 

 tibial spines slim and numerous, claw-hooks robust, situated near the 

 midelle of the claws. Armature of the female very similar. 



Abdomen very long and slim. The first 3 segments markedly tumid from 

 side to side and ventro-dorsally, the remainder cylindrical, very slim and 

 parallel-sided to the end. The joints of the segments markedly swollen. 



Anal appendages very long and slim, nearly as long as the two last 

 abdominal segments. 



Wings long and moderately broad, reticulation close. Trigone of the 

 f ore wing shghtly distal to the line of that of the hind, its relation to the 

 hypertrigone about a right angle, traversed once, very narrow, trigone of 



