162 DIPTERA. 
broader than the lateral portions ; frontal bristles descending to a little beneath the root of the antenne ; 
cheeks narrow; eyes densely clothed with a whitish pile. Antenne black, descending to the vibrisse ; 
second joint with short bristles; third joint four or five times as long as the second ; arista thickened to 
its proximal third. Proboscis and palpi black, the palpi with a clearer, somewhat rufous tip. Thorax 
black, before the transverse suture with some grey tomentum and four black stripes, which, however, are 
not always distinct. Abdomen conical, black, with the front borders of the second and following segments 
white ; on the second and third segments the white colour is interrupted by a black dorsal stripe; the 
macrocheete are very short, the discal ones sometimes inconspicuous. Legs black ; front tibie outwardly 
with a row of short bristles; middle tibie with some long bristles; hind tibie outwardly nearly fringe- 
like with bristles; foot-claws and pulvilli short in both sexes. Tegule whitish. Wings nearly hyaline , 
small cross-vein on the middle or just before the middle of the discal cell; apical cross-vein straight ; 
posterior cross-vein very slightly curved. 
Hab. Mexico, Venta de Zopilote 2800 feet, Amula 6000 feet, both in Guerrero 
(H. H. Smith). 
A male and two female specimens. 
11. Didyma pullula, sp. n., 2. 
Blackish ; thorax cinereous, with black stripes; abdomen with whitish reflecting spots and with discal and 
marginal macrochete ; palpi rufous. 
Length 4°5 millim. 
Front cinereous, slightly prominent, much broader than the eyes; frontal band a little narrower than the 
lateral portions; frontal bristles descending as far as the end of the second antennal joint; face and 
cheeks whitish ; eyes distinctly pilose. Antenne black, shorter than the face; second joint bristly ; 
third joint rather broad, four times as long as the second; arista thickened to its proximal half. Pro- 
boscis black; palpi pale rufous. Thorax greyish-cinereous, with four black stripes, the intermediate 
stripes very distinct before the transverse suture ; scutellum black, its hind margin slightly testaceous. 
Abdomen ovate, shining black, with whitish reflecting spots, chiefly on the front borders of the second 
and following segments ; discal and marginal macrocheete are present, but the marginal ones are longer 
than the others. Legs black ; middle tibiz with some long bristles; hind tibie outwardly with bristles 
of unequal length. Tegule whitish. Wings with a brownish-grey tint, which is more intense towards 
the base ; the veins strong; small cross-vein slightly infuscated, inserted before the middle of the discal 
cell; curvature of the fourth vein angular ; apical cross-vein curved ; posterior cross-vein nearly straight, 
inserted much nearer to the curvature of the fourth vein than to the small cross-vein. 
Hab. Mexico, Sierra de las Aguas Escondidas in Guerrero 9500 feet (H. H. Smith). 
A single female specimen. 
12. Didyma albomicans, sp. n.,¢ ¢. 
Black ; thorax grey, with four black stripes; abdomen with white reflecting spots and with discal and 
marginal macrochete ; palpi rufous. 
Length 3°5-5 millim. 
Head whitish-grey ; front as broad as the eyes; frontal band black, a little narrower than the lateral portions ; 
frontal bristles descending as far as the end of the second antennal joint; facial bristles mounting to the 
same point. Eyes with a weak pile, and descending as far as the tip of the antenne. Vibrisse inserted 
a little above the oral margin. Antenne shorter than the face; third joint four times as long as the 
second ; arista thickened to the proximal half. Thorax with grey tomentum, which appears chiefly on 
the sides and anteriorly ; four black stripes are rather distinct before the transverse suture. Abdomen 
shining black, conical in the male, ovate in the female ; the whitish reflecting spots chiefly on the front 
borders of the second and following segments; the macrochete of moderate length. Legs black, bristly ; 
