LAMB—DIPTERA: HETERONEURIDA, ORTALIDA, TRYPETIDA, SEPSIDAM, ETC. 349 
‘exceptionally large bristles ; 3rd joint small, darkened, somewhat silky ; arista darkened 
except for basal one-fourth; 3 or 4 upper, 3 lower, terminal, and a few fine inner rays. 
The yellow face is very slightly concave; large vibrissa, the following bristles just on 
mouth margin, they are 4 in number and very stout, nearly as big as the vibrisse ; hind 
jowls yellow with two spines: a long one on back of mouth. Post-orb. row evident, two 
long ones behind v. b. 
Thorax. Shining orange, a slightly darkened spot just behind humeri, entirely 
covered with fine bristles which form some 8 irregular acr. rows. Two d.c., the front the 
shorter, h., n. p., presut., 3 over wings. Scutelluim as thorax but bare, tip rather obtusely 
rounded ; two sub-basal bristles, two long terminal, slightly converging towards tips. 
Wings, Fig. 32, tip white, costa darkened up to this tip; all the veins pale. Halters 
whitish yellow. Legs: front coxee pale, femora and tibiz black, -except at base, Ist 
tarsal joint black, the others yellow. Mid and hind legs all yellow. 

Fig. 32. Chymomyza bicolor, n. sp. x 50. 
Abdomen. Entirely shining black, covered with short dark bristles, which show up 
light in oblique illumination. 
Size, over 2 mm. ; wings, about 13 mm. 
Locality. Seychelles. Mahé: Cascade Estate, about 1000 feet, I. 1909. 
é 
DETTOPSOMYIA, n. g. 
There are 5 somewhat badly preserved specimens of a very remarkable Drosophilid 
of quite unusual facies, which must be referred to a new genus (Plate 20, fig. 36). 
Head. Top view (Plate 20, fig. 37) :—head wider across eyes than long, the eyes are 
covered. with short bristly hairs, they project backwards. F rons broader than wide, 
roughly rectangular in form with a well-marked sutural fold over the antenne. Eye- 
margins very wide. Ocelli nearly in the middle of the frons. The cheetotaxy is abnormal : 
in front over antennze are two f. o., the smaller forward inner one being slightly bent 
forward, the neighbouring backward outer one being longer, and slightly bent back. On 
the swollen hind eye-margins are two more bristles, which can best be looked on as the 
vertical pairs: the front bristle (corresponding to inner vertical) is nearly upright, the hind 
(or outer vertical) bends outwards. The p. v. pair are strongly crossed and are low down 
on back of head; the oc. are divergent and are situated almost on the ocellar area, but 
the bases are outside the line joining the front to the side ocellus. Front view (Plate 20, 
45—2 
