172 CYRTIDJK. 



yellowish-grey pubescence, which extends over the upper pleurae 

 and the scutellum ; the large posterior calli reddish brown, as is 

 the posterior margin of the scutellum wholly (type) or in part 

 (cotype) ; a similarly coloured spot on pleurae about halfway 

 between base of wing and middle coxa? : lower part of pleura? 

 blackish grey, bare of pubescence, but with microscopic grey dust. 

 Abdomen with ground-colour black, surface slightly roughened ; 

 the very short 1st segment with an extremely narrow bone- white 

 hind margin ; remainder of segments with similarly coloured hind 

 margins, narrowest on 2nd segment, especially in the middle, 

 broadest on 3rd, 4th, and 5th segments ; the white margin does 

 not reach the actual sides of the dorsal plates (except on oth and 

 perhaps 6th segments), though a fiue pale yellowish-white line 

 does actually continue right through to the extreme edge. The 

 side-margin of the dorsal plate is occupied by a moderately broad 

 black baud, which practically dies away just beyond middle of 

 5th segment. Venter mainly bone-white ; base of most segments 

 blackish brown, narrowly in middle and broadly towards sides, 

 leaving a whitish stripe below the black side-margins of the dorsal 

 plates ; towards each side of the 2nd, 3rd, 4th, and 5th segments 

 is a rather large reddish-brown spot, fairly well demarcated from 

 the black and bone-white parts. Legs with coxae and about basal 

 two-thirds of anterior femora and three-fourths of hind pair 

 shining black, remainder reddish brown ; tibiae reddish brown, 

 about middle half of bind pair blackish ; all tarsi black. Wings 

 absolutely clear and transparent practically to the extreme base ; 

 veins yellow, costa dark brown ; thoracic squamae pale dirty 

 white, with whitish microscopic pubescence and a very narrow 

 pale yellowish border; halteres brownish yellow. 



Length, type 6 mm., cotype 4| mm. 



Described from two specimens in the British Museum from 

 Nuwara Eliya, Ceylon, 18. v. 1891 {type), and 14. viii. 1891 

 (Yerbury). 



In the cotype the reddish-brown spots towards the sides of the 

 abdomen are less well delimited; the general ground-colour of 

 the abdomen is more nearly very dark brown than black ; the 

 pale hind border on the 2nd segment is broader than in the type; 

 and the red on the scutellar hind border is confined to the central 

 part. This specimen bears a label: " rare, seated on grass stalks." 



On comparing the present form with the very lengthy description 

 of O. gibbosus given by Verrall, the agreement is certainly striking ; 

 but, though that author says he examined a large number of speci- 

 mens, he makes no mention of the very conspicuous reddish- 

 brown posterior calli and hind margin to the scutellum. It seems 

 justifiable, therefore, to regard the present form as a distinct 

 species. 



