Bombyliadae (Diptera) from Central Africa. 615 
8. Petrorossia, Bezzi (1908). 
This genus was ereeted by me for the well-known 
Mediterranean Argyramoeba hesperus, and is included in 
the monograph of Dr. Sack (1909), with this species alone. 
I am uow very glad to find that it is well represented in 
Africa, as the collection comprises no fewer than four 
distinct species. 
The genus is easily distinguishable from any of its allies ; 
it most closely resembles Chionamoeba, Sack, from which 
it differs chiefly in the form of the discal cell and in the 
origin of the second longitudinal vein. 
The species before me can be distinguished as follows :— 
1 (4). Species more robust and of greater size, without golden 
tomentum on thorax, scutellum and abdomen ; frons 
opaque ; abdomen wholly brown, or with a small yellow- 
ish marking on the sides only. 
2 (3). Frons with black hairs; abdomen wholly brown, or with 
only a small yellowish patch at the extreme base, with 
black bristles on the sides ; upper branch of third vein 
normally with a recurrent veinlet . hesperus, Rossi. 
3 (2). Frons with white hairs; abdomen with a narrow yellowish 
lateral stripe along its whole length and without black 
bristles on the sides ; upper branch without appendix 
letho, Wied. 
4 (1). Smaller and delicate species, clothed with golden tomentum ; 
abdomen orange-red, with or without a median longi- 
tudinal dark stripe ; frons shining black. 
(6). Face with white hairs ; abdomen with a broad median black 
stripe ; second longitudinal vein strongly bent near the 
apex ; upper branch of the third vein bent at an angle 
and_here with an appendix ; anal cell narrowly open 
fulvipes, Loew. 
6 (5). Face with black hairs; abdomen without median stripe ; 
- second vein slightly curved, as also the upper branch of 
the third, which is without appendix ; anal cell widely 
open A 5 : : . : . gratiosa, sp. n. 
16. Petrorossia hesperus, Rossi (1790). 
A single female of great size (length 10 mm.), from N, 
Nyasa, on the road from Karonga to Fort Hill, near 
Kaseye, June 1, 1909 (Dr. J. B. Davey), which agrees very 
well with our Italian specimens. The femora are wholly 
yellow, and there is no appendix to the upper branch of 
the third vein; the wings are hyaline, and only slightly 
infuscated toward the fore margin. 
or 
SS 2 
