12 DIPTERA. 
11. Abdomen with black dorsal spots, which are sometimes united 
to a longitudinal band; anus (besides the black spines) with 
red pilosity . . . 2... . ee ee ee dorsalis, v. d. Wulp. 
Abdomen without dorsal spots, but only the last segment black, 
with pilosity of the same colour. . . ..... . . . pyrrhaspis, Wiedem. 
1. Hystricia albiceps, sp.n. ¢. (Tab. I. fig. 6.) 
Bluish-black ; abdomen light grey ; head whitish; antenna, palpi, and legs black ; third joint of the antenne 
a little longer than the second ; wings infuscated. 
Length 14 millim. 
Face and cheeks white, with blackish reflections; face a little declivous, with the oral margin projecting; the 
cheeks beset with weak hairs; above the vibrissae are some short bristles ; a few bristles also at the lower 
borders of the cheeks; beard white. Front narrowed near the vertex, blackish-grey, with a piceous 
median band and a weak and dark pilosity ; frontal bristles abundant, descending to a little beneath the 
root of the antennz ; occiput with grey-and-black mixed pile. Eyes densely clothed with yellowish hairs. 
Second joint of the antenne with many bristles; third joint a little longer and broader than the second, 
rounded at the apex. Proboscis black; the palpi broad, prominent, clothed with greyish tomentum, and 
beset with black bristles. Thorax and scutellum with a grey tomentum, the front part of the thorax 
with four longitudinal black stripes and more distinct tomentum; macrochezte of the thorax long and 
robust, those of the scutellum ranged in two rows and more in the form of spines. Abdomen broader 
than the thorax, with light bluish-grey tomentum, the tomentum covering the ground-colour; second 
segment in the middle and at the sides, and the third segment over its entire breadth, densely beset with 
black spines; fourth segment, except its front border, with numerous black bristles and spines ; venter 
with spines in the middle. Legs rather slender; front femora outwardly with grey tomentum ; bristles 
of the legs moderately long and stout, those at the outside of the middle tibie longer; claws and pulvilli 
yellow, the former with black tips. Tegule and wings brown; the small cross-vein of the latter placed 
somewhat before the middle of the discal cell; the apical cross-vein incurved at its base; the posterior 
cross-vein like a straight line, slightly waved. 
Hab. Costa Rica, Rio Sucio (Rogers). 
A single male specimen. 
2. Hystricia infuscata, sp.n., 2. 
Black ; thorax and scutellum with cinereous tomentum ; head yellowish; basal joints of the antenne rufous, 
the third joint black and a little longer than the second; palpi pale rufous; abdomen piceous, with 
scattered spines ; legs black ; wings dark grey, fuscous at the base and along the costa. 
Length 9:5 millim. 
Head pale yellow ; face vertical, prominent towards the oral margin ; front yellowish-grey, a little narrowed 
behind, but even on the vertex broader than the diameter of the eyes; frontal bristles descending to the 
number of three or four beneath the root’ of the antennew, the outward bristles and those on the vertex 
stouter ; vibrisse robust, with a few shorter bristles near them ; beard and a rather dense pilosity on the 
cheeks yellowish. Basal joints of the antenne rufous; second joint elongate, broader towards the end, 
with several black dorsal bristles; third joint black, broader and a little longer than the second, convex 
at the front side, rounded at the apex ; arista black, indistinctly jointed. Proboscis shining black ; palpi 
pale rufous, enlarged towards the end, with short black bristles. Thorax and scutellum black, with 
cinereous tomentum—this before the transverse suture is more compact, and shows four black longi- 
tudinal stripes, the two median of which are linear. Abdomen convex, shining, piceous, with black pile ; 
the spines not numerous and regularly arranged, the dorsal ones as well in the middle as on the hind 
borders of the segments. Legs black; the front femora outwardly with grey tomentum ; bristles of the legs 
long and stout, especially those of the outside of the middle tibie ; foot-claws black, the pulvilli yellow. 
