322 PERCY SLADEN TRUST EXPEDITION 
Thorax. In good specimens the colour is pale grey all over except that the sides are 
a little darker. When this grey pollination is rubbed off or otherwise spoiled, the ground 
colour is black with the humeri and a patch between them and the wing bases distinctly — 
orange. The dorsum is rather irregularly clothed with small bristles of type § arising 
from scattered tiny irregularly distributed black dots. These small bristles are larger on 
the prothorax and a pair just on edge behind head is very distinct. The ground colour 
shows to a more or less extent through the orangish grey pollen, and one may often dis- 
tinguish it to form indistinct thoracic lines, e.g. one from the above mentioned pair of small 
bristles in front down to the level of the first d. c. pair. The macrochetes stand on dark 
spots; these are: 2 pair d. c., the front just behind cross suture, h., n. p., presut., 3s. a., also 
st. p.andmesop. All these are of type a. Scutellum as thorax with two large div. discal 
bristles on blackened spots, a small black crossed terminal pair not on spots: sometimes 
there are in addition one or two small scattered bristles of type 8. The outline of the 
scutellum is a shallow rounded triangle. The metanotum is large, two ridged, grey on 
top and blackened beneath. 
Wings as in Fig. 13. They have the remarkable “bulle” characteristic of 
this and the related genera, the position of these being shown in the figure. The 
general scheme of colour is as shown in the figure, and is black. The venation 
is not typical. In de Meijere’s description and figure the distances on the costa 
between the end of the second vein and that of the 3rd is about equal to that between 
the 3rd and 4th. In this species, the second vein meets the costa roughly midway 
between 1 and 3, and is curved up; also, the 4th vein is not straight, but is remarkably 
undulate as shown. The dotted line in Fig. 13 just below the third vein shows where 
a fold occurs (the “sulcus cubitalis” of Girschner, see Kertész, Ann. Mus. Nat. Hung., 
1903, p. 358); when viewed from beneath this appears as a well chitinized extra vein. 
Unlike de Meijere’s figure and description (where no discal cross vein is shown or 
mentioned) that vein is here well developed. The coxal nick and its two bristles are 
very well developed. The rest of the venation is readily seen from the figure. No bristles 
occur on any veins. The halters are clear orange-yellow. 
The legs are yellow except for two incomplete darkened rings at the ends of front 
femora, the whole of mid and hind femora are darkened except at the tips, and there is 
a dark ring near the base of the middle and hind tibize. Two upper rows of bristles on 
front femora all weakly developed, black, and with 4 bristles each: a lower row of 3 
stouter bristles, the first black, the next two white ; terminal spine to mid-tibize, no other 
well-marked bristles. 
Abdomen. ¢ darkish grey with silvery hairs; the hypopygium very projecting 
from below base: last segment bordered with stout black bristles. ¢, last segment 
forming a flattened sheath about as long as rest of abdomen. 
Size g, over 25 mm. ; wing, about 3 mm. 
Localities. Seychelles. Silhouette; from near Mont Pot-i-eau, ca. 1500 feet, VIII. 
1908. Mahé: from near Morne Blanc, X.—XI. 1908; Cascade Estate, ca. 800 feet, 
1908—9. This species was swept from grass in forest-clearings &c. 
