382 DIPTERA. 
4. Cross-bands very broad, the first three contiguous at the hind margin, 
the third and fourth united at the costa. . . . . ee Conjuncta, Low. 
Cross-bands of moderate breadth or narrow. . . . . 5. 
5. The second cross-band in the middle largely united with the first . . connecta, v.d. W. 
The second cross-band over its whole length separated from the first, or 
(in R. pilosula) united with it only inferiorly . . . 6. 
6. The blackish pattern at the base forming with the first cross- band a lar ge, 
curved spot, which is not interrupted by hyaline portions . . . flexuosa, v. d. W. 
The blackish pattern at the base, in connection with the first cross- band, 
interrupted by hyaline spots . . . . . | . . Woe 
7. The first cross-band much broader than the others and connected j in the 
discal cell with the second cross-band. . . . . pilosula, v. d. W. 
The cross-bands equal in breadth, the first not connected “with ‘the 
second . 2. we ee ee ee ee ee ee ee Longicornis, v. d. W. 
1. Rivellia occulta, sp.n., ¢ @. (Tab. X. fig. 8, wing.) 
Black ; head, antennew, and legs rufous; wings hyaline, with three linear cross-bands and a blackish apical 
spot. 
Length 2 millim. 
Head rufous ; front as broad as the eyes, with parallel sides ; occiput blackish. Antenne rufous, usually a 
little infuscated towards the tip; shorter than in the allied species. Proboscis black. Thorax, scutellum, 
and abdomen black ; thoracic dorsum with some cinereoas dust ; scutellum with two rather long bristles ; 
abdomen elliptical, in the female more elongate; first joint of the ovipositor flattened, brown; the second 
cylindrical, pale rufous. Legs yellowish-rufous, the terminal tarsal joints slightly infuscated. Halteres 
yellow. Wings hyaline; three narrow brownish cross-bands extending from the costa to the fifth vein— 
the first and second oblique, the second bordering the small cross-vein, the third perpendicular, bordering 
the posterior cross-vein, the first and second sometimes interrupted at the fourth vein; a more or less 
extended brownish spot at the tip of the wing. : 
Hab. Mexico, Chilpancingo 4600 feet, and Omilteme 8000 feet, both j in Guerrero 
(H. H. Smith). 
Six males and one female. One of the males is a little larger in size (length nearly 
3 millim.), and has the front and face more brownish ; it is probably a variety. 
2. Rivellia micans, (Tab. X. fig. 9, wing.) 
Rivellia micans, Low, Monogr. Dipt. N. Amer. iii. p. 94°. 
Hab. Nortu America; Texas '.—Mexico, Northern Sonora (Morrison). 
A single male specimen, agreeing with Low’s description ; it is of a bright metallic 
coloration ; the reddish cross-band on the abdomen is road, and occupies a large 
portion of the second and third segments. 
3. Rivellia submetallica, sp.n. 3. (‘Iab. X. fig. 10, wing.) 
Black, slightly metallic; front and legs rufous; tibia brown ; the first cross-band angular. 
Length 4 millim. 
Front dark rufous, a little broader than the eyes, with parallel sides ; face distinctly excavated, greyish ; the 
clypeus and the cheeks pale rufous ; inferior portion of the cheeks larger than in the other species of the 
