384 | DIPTERA. 
Head black; front in the middle brownish, immediately before the antenne with two small, rufous 
protuberances ; face slightly concave; occiput shining black. Antenne rufous, on the outer side 
brownish. Thorax, scutellum, and abdomen shining black ; scutellum with two long bristles ; abdomen 
elliptical. Legs black, the tarsi, save the last two or three joints, yellowish-rufous ; the femora somewhat 
elongate; the hind tibie slightly curved. Halteres brown. Wings hyaline, with a blackish pattern ; 
the first cross-band broad, completely united with the blackish base, on the outer side convex, inferiorly 
reaching to beyond the fifth vein; the other cross-bands narrower ; the second issuing from the costa at 
the termination of the first vein and in an oblique direction reaching the small cross-vein, where it is 
angularly curved and goes more perpendicularly to the hind margin of the wing; the third cross-band 
straight, at the hind margin connected with the second and at the costa with the fourth, which borders 
the tip of the wing. 
Hab. Mexico, Omilteme in Guerrero 8000 feet (fH. H. Smith). 
A single male specimen. 
7. Rivellia pilosula, sp.n.,¢. (Tab. X. fig. 14, wing.) 
Blackish, with grey pilosity ; first cross-band broad, connected with the blackish base of the wing and 
inferiorly with the much narrower second cross-band, the third and fourth bands united at the costa, 
Length 2°5 millim. 
Front brownish-rufous, as broad as the eyes, with parallel sides; face greyish, very slightly excavated ; inner 
orbits of the eyes white. Antenne rufous; the third joint more obscure, somewhat pointed towards the 
tip, reaching to near the oral margin. Proboscis black, thick. Thorax, scutellum, and abdomen black, - 
covered with short greyish hairs ; the abdomen ovate, posteriorly pointed; second joint of the ovipositor 
pale rufous. Legs piceous, somewhat dark rufous, the tarsi clearer. Wings hyaline; the first cross- 
band much broader than the others, connected with the blackish base, the separation being only indicated 
by one or two small, elongate, hyaline spots ; the second cross-band united with the first just before the 
small cross-vein, the two prolonged together in a less intense infuscation in the middle of the discal cell ; 
the third cross-band united with the fourth and with it forming a narrow border round the tip of the 
wing. 
Hab. Mexico, Teapa in Tabasco (H. H. Smith). 
A single female specimen. 
8. Rivellia longicornis, sp.n., ¢ ¢. (Tab. X. fig. 15, wing.) 
Shining black ; head and antenne rufous; legs piceous, partly dark rufous ; cross-bands of equal breadth, the 
third and fourth narrowly united on the costa. 
Length 3°5-4°5 millim. 
Front dark rufous, a little broader than the eyes, with parallel sides; face clearer rufous, perpendicular ; 
inner orbits white. Antenne rufous, longer than in most other species of the genus, reaching the oral 
margin. Proboscis thick, black; palpi rufous. Thorax, scutellum, and abdomen shining black; the 
abdomen ovate, pointed towards the tip, covered with greyish hairs, but less densely so than in the 
preceding species (f. pilosula); male genitalia with two filiform appendages on the ventral side ; 
ovipositor of the female rather narrow, three-jointed, the first two joints flattened and black, the third 
cylindrical, pale rufous. Halteres black. Wings hyaline, with blackish cross-bands; the first cross-band 
not broader than the others and connected with the blackish base, the second isolated, the third prolonged 
and forming a border along the end of the costa and the tip of the wing. 
Hab. Mexico, Omilteme in Guerrero 8000 feet (H. H. Smith). 
A single specimen of each sex. 
