408 



Records of the Indian Museum. [Vol. XXIV, 



Ki<; 



>o. — Anal appendages of Onycliogomphus] 

 acinaces, sp. nov. <?, side view. 



Ventral surface black, meso and metanotum marked with 

 lemon yellow. Legs entirely black. 



Abdomen longer than wings, swollen at its base and again 

 enlarged from segments 7-9. Black in colour. Segments 1-2 



with mid- dorsal yellow 

 bands. 3-6 with basal 

 rings of yellow occupy- 

 ing about the basal 

 sixth of each; these 

 rings are contracted in 

 the middle line dor- 

 sally. Basal half of 

 seventh segment lemon 

 yellow. First and second segments, including the oreillets, marked 

 with yellow. Eighth segment with basal, lateral spots of the same 

 colour. 



Anal appendages, upper pair as long as ninth and tenth abdo- 

 minal segments together, yellow, darker at apex, internally, and 

 ventrally, tapering, parallel, curving downwards in their distal 

 half. Lower appendage one-quarter as long again, its outer 

 four- fifths bifid. The branches are parallel, closely approximated, 

 and curve upwards for their distal half. Seen in profile the lower 

 appendage is rather scimitar-shaped, and projects well beyond the 

 end of the upper pair. They are entirely black. 



The venation is that characteristic of the genus. The bases 

 of both pairs of wings are distinctly tinged with dark brown, espe- 

 cially in the sub-costal space, where the colouring extends as far 



16 14 , , 10 12 



— — : post nodals — — . 

 11 11 11 12 



as the first cross-nerve. Antenodals 



Length of abdomen 33 mm. +3'75 mm. (lower appendages) 

 of hinder-wing 30 mm. 



Apparently related to 0. biforceps Selys, but with the anal 

 appendages less strongly curved. It differs also in the distinct 

 colouring of the wing-bases, rather unusual in Gomphines, and 

 generally in the great extent of black colouring on the thorax. 



The males of the species of this section may be distinguished 



as follows : — 



A. Dorsal stripe confluent with mesothoracic 

 collar ; anlehumeral stripe absent ; anal append- 

 ages black, segment 8 of abdomen with a pair 

 of dorsal prominences 



B. Dorsal stripes of synthorax isolated. 



1. Antehumeral stripe complete ... 



2. Antehumeral stripes absent 



O, camelus Martin. 

 Tonkin. 



0. biforceps Selys. 



Tonkin ; India. 

 0. acinaces, sp. 1 



W. India. 



The small species, 0. modestus Selys, the hinder-wing of 

 which has a length of 23 mm., would appear to have some right 

 to be included in the present group on account of its generally 

 dark colouration. The synthoracic colour -pattern is in fact very 



