DIDYMA. 16] 
8. Didyma timida, sp. n.,¢ 2. 
Blackish ; thorax anteriorly whitish-grey, with black lines; abdominal segments with narrow white front 
borders ; posterior cross-vein in the middle between the small cross-vein and the curvature of the fourth 
vein. 
Length 5°25 millim. 
Front cinereous, as broad as the eyes, in the male scarcely narrowed behind; frontal band black, nearly as 
broad as the lateral portions; frontal bristles descending as far as the end of the second antennal joint ; 
face and cheeks blackish, the cheeks narrow and with a whitish reflection; eyes thinly pilose. Antenne 
black ; third joint four times as long as the second; arista thickened to near the middle. Proboscis 
black ; palpi black or dark rufous. Thorax and scutellum black; thoracic dorsum before the transverse 
suture with a whitish tomentum and four black lines. Abdomen conical, black ; second and following 
segments with narrow white front borders, which in the middle are interrupted by a black dorsal line ; 
discal and marginal macrochetz present, the marginal ones longer than the others. Legs black; middle 
tibie with some long bristles; hind tibia outwardly with bristles of unequal length; foot-claws and 
pulvilli short in both sexes. Tegule white. Wings greyish-hyaline ; small cross-vein on the middle of 
the discal cell; third vein nearly straight ; apical cell very narrowly opened just before the wing’s tip ; 
apical cross-vein oblique and straight ; posterior cross-vein less oblique, nearly straight, inserted in the 
middle between the small cross-vein and the curvature of the fourth vein. 
Hab. Mexico, Amula in Guerrero 6000 feet (H. H. Smith). 
Two males and one female. 
9. Didyma vagabunda, sp. n., 2. 
Black ; thorax anteriorly grey, with four black stripes; abdomen with whitish front borders to the segments 
and with discal and marginal macrochetee. 
Length 7:5 millim. 
Front with whitish reflections, slightly prominent and a little broader than the eyes, narrowed behind ; frontal 
band black, attenuated towards the vertex; frontal bristles on each side forming a nearly continuous row 
with the bristles on the facial ridges ; on the sides of the front several other bristles close to the orbits of 
the eyes; face and cheeks with white and blackish reflections; eyes thinly pilose. Antenne black, 
distinctly shorter than the face; second joint bristly ; third joint four times as long as the second, 
truncate at the tip; arista thickened to its proximal half. Proboscis and palpi black; the palpi cylin- 
drical and longer than in the other species of the genus. Thorax and scutellum black, the shoulders and 
the thoracic dorsum before the transverse suture whitish-grey, with four black stripes, the outer stripes 
much broader than the others. Abdomen short-conical, black; second and following segments with 
’ whitish front borders and with long marginal and somewhat shorter discal macrochetz. Legs black ; 
middle tibis with some long bristles; hind tibie outwardly with several bristles of unequal length. 
Tegule whitish. Wings greyish-hyaline ; small cross-vein a little before the middle of the discal cell; 
curvature of the fourth vein with a rounded angle; apical cell attenuated near its end and narrowly 
opened just before the wing’s tip; apical cross-vein straight, only a little concave at its end; posterior 
cross-vein curved outwards at its lower part. 
Hab. Mexico, Omilteme in Guerrero 8000 feet (H. H. Smith). 
A single female specimen. 
10. Didyma prompta, sp. n., ¢ 9. 
Blackish ; thorax anteriorly greyish, with indistinct stripes; abdominal segments with white front borders 
and short macrocheete. 
Length 5-5°5 millim. 
Head blackish; front in both sexes scarcely as broad as the eyes, with parallel sides; frontal band black, 
BIOL. CENTR.-AMER., Dipt., Vol. II., June 1890. y 
