164 JOURNAL, BOMBAY NATURAL HIST. SOCIETY, Vol XXVI. 



Abdomen : moderately dilated at the base, then cylindrical and parallel- 

 sided to the anal end ; very variable in colouring, either all black and more 

 or less frosted with blue or else the anterior segments a greenish yellow 

 (usually the 1st to 3rd) ; the autures fir.ely mapped out in black, a diffuse, 

 sub-dorsal, brown stripe. The rest of the abdomen obscurely greenish 

 yellow and bordered on either side, broadly with black. 'Jhe whole of the 

 segments, 4 to 10 usually frosted with blue through which the markings 

 show morrt or less faintly. 



Genital organs of the male : lamina wide and procumbent, covered to a 

 variable extent with long, coarse hairs, its sides laterally curling or 

 thickened and the apex notched. Internal tentacula foliate and membran- 

 ous, ending in a small, outwardly directed hook; external tentacula 

 broadly triangular and capped on the outer surface ; the lobe not project- 

 ing, sloping weU back, broad, shaUowly arched and coated with stiff, coarse 

 hairs. 



Female : very similar to the male but rather brighter coloured. 

 Haad : eyes are paler, the labrum and the face a brighter green. 

 Thorax : always a light yellowish green laterally and with practically no 

 markings. 



Abdomen : similar to the male but the black bordering narrower and con- 

 sequently the greenish yellow more extensive. No blue frosting as in the 

 male. Much stouter than in the male and cylindrical. 

 Anal appendages small and black. 



Wings hyaline, often with a marked smokiness. With or without a basal 

 marking, which, if present, extends in the forewing as far as the l&t 

 antenodal nervure and the cubital nervure ; in the hindwing it extends as 

 far as the 2nd antenodal, nearly as far as the trigone and into the border of 

 the loop. 



Genital organs of female: S\h. abdominal segment markedly dilated; 

 vulvar scale small, deeply notched and semi-bipartite ; 9th ventral plate 

 tumid. 



Remarkable polymorphism and polychroism is found in this species and 

 gives rise to much confusion in classification. The blue frosting of the 

 male is extremely variable, some specimens being densely frosted whilst 

 others have the merest trace. The thoracic markings vary widely, Kis 

 describing specimens from the Nilgiris, gives the markings as very exten- 

 sive, whilst in the specimens that I possess from the same locality, 

 save for the humeral stripe, the markings are almost or entirely 

 obsolete. 



The dark, basal line on the forehead seems to be constant, being present 

 m specimens from Ceylon, Nilgiris, Burma and Malabar. Specimens from 

 Deesa agree with my Nilgiri ones. The labium varies in its colouration 

 considerably ; thus His f''e scribes a pair from Burma, where the labium of 

 the male is completely black, and in the fen^ale, only the middle lobe 

 similarly coloured. In Nilgiri specimens the labium is usually completely 

 yellow. Burma specimens possess 1 row of cells between 5 and 5a, as do 

 also those from Gilgit, whilst, others from the Nilgiris, Deesa, and Ceylon 

 may have either 1 or 2 rows of cells. 



Hab. Throughout India except the desert tracts, Nilgiris, Ceylon 

 and Burma. 



23. Orthetrum triangulare triangulare, Kirby. 



Lihella trinm/ularis, Selys. 

 Lihella delesfrli, Kirby. 

 Orthetrum dele-ferfi, Kirby. 

 Orthetrum cai-naticum, Kirby. 



