LAMB—DIPTERA: HETERONEURIDA, ORTALIDA, TRYPETIDA, SEPSIDA, ETC. 369 
vibrissa on the mouth angle is followed along the edge by 4 or 5 extra ones progressively 
diminishing in size, and pointing away from vertical plane of head. 
Thorax. Orange with a minute orange-grey granulation, dorsum all bristly with 
fine bristles which form very irregular acrostichal rows of some 6 bristles wide between 
the d. c.’s. There are (1+8) d.c., the last somewhat outside the line of the first three ; 
prescutellars, one large humeral and two other smaller ones on the humeral callus ; two 
not. ; presut., mesopleura with bristles, of which three are practically macrochetes, a stout 
bristle and smaller one on prothorax over cox. Scutellum flattened, same colour as 
thorax, the dorsum with a few scattered bristly hairs, a basal and crossed terminal pair. 
Wings, as Fig. 48, glassy with pale yellow veins, no distinct variation in costal bristles, 
though they are stouter from 2nd vein to base than from 4th to 2nd. Halters all yellow. 
Legs all yellow, no very outstanding bristles, except upper and lower row on front femora ; 
the mid tibia with terminal spines. 

Fig. 48. Rhicnoessa aurisetulosa, n. sp. x 30. 
Abdomen. In male each segment (2nd to last) has its basal half orange, sometimes 
getting black from internal discolouration, and the distal half greyish orange: the line of 
demarcation is very sharp ; bristles on dorsum, longer along hind margins, somewhat tufted 
bristles (in top view) at upper side of 2nd segment. There is a rounded knobby genital 
segment at end, not bent beneath, with small scale-like appendages ; the ? abdomen is all 
orange, segments subequal, with a soft ovipositor. 
Size, just over 24 mm. ; wing, just over 2 mm. 
Localities. Seychelles. Mahé: from seaweed on beach, Anonyme Island, I. 1909, 
a considerable number ; from seaweed, Long Island, VII. 1908, 6 specimens. 
