1922.] F. F. Laidlmv : Indian Dragonflies. 409 



similar to that of 0. acinaces. De Selys regarded it as'fallied 

 closley to 0. saundersi. I have not seen a specimen but am in- 

 clined to refer it here, rather than to the geometricns group. 



Onychogompbus, sp. 



i?. Garo Hills, Assam, 1200-1500 ft., June-July, 1917. S. Kemp, 

 (7979/H1). 



This specimen is apparently quite distinct from any yet des- 

 cribed, its exact position is doubtful, but it seems to me possibly 

 allied to 0. biforceps hence I describe it briefly here. 



Head: upper lip black, base of mandibles yellow, ante-clypeus 

 yellow. Post-clypeus black, frons black with narrow yellow band 

 across its crest, head otherwise black. Posterior margin of occiput 

 slightly elevated in the middle line. 



Prothorax black above, yellow below. 



Synthorax with a black dorsum, marked with a yellow meso- 

 thoracic collar, which is continuous across the mid-dorsal carina, 

 and a pair of narrow, isolated dorsal bands. No trace of ante- 

 humeral bands. Sides of synthorax yellow, with a broad black 

 band on the first lateral suture, and a narrower band of grayish 

 brown along the position of the second suture. 



Legs black, anterior femora yellow internally, posterior pair 

 yellow extero-laterally. 



Abdomen black, sides of first and second segments yellow. 

 Dorsum of first segment yellow, of second segment marked with a 

 longitudinal trilobed band of the same colour. Segments 3-6 with 

 basal ring of yellow, interrupted mid-dorsally, occupying about 

 the first sixth of each segment. In addition segments 3-5 have a 

 median longitudinal mark of yellow on the dorsum. The basal 

 half of 7 is yellow; 8, 9 and 10 are black, but 8 has a small basal 

 lateral mark of yellow on either side. Anal appendages small, 

 brownish-white. Apical half of seventh segment dilated from side 

 to side, the succeeding segments progressively narrower. The 

 sternite of the eighth segment is produced apically in a downward 

 direction, so that it is visible in profile. The vulvar scale, pro- 

 tected by this projection is small, bifid apically. 



A similar development of the sternite of the eighth segment of 

 the abdomen occurs in certain species belonging to the Gomphns 

 series (e g. Gomphus melampus Selys), but I do not know of any 

 other Onychogomphus which shows a similar development. Vena- 

 tionally and in colouration, however, I do not doubt but that this 

 specimen is a true Onychogomphus. 



Length of abdomen 37*5 mm., of hinder-wing 35 mm. 



The following species, known only from female examples, 

 resembles this specimen to some extent in the colouring of the 

 synthorax. 



0. frontalis Selys, Moolai, <c between Burma and Tenasserim." 



Dorsal stripes of synthorax isolated, vestige of a juxta-humer- 

 al band present. T-shaped mark on dorsum of frons. Occiput 



