244 DIPTERA. 
light grey. Legs black, the femora with whitish tomentum ; the tip of the front cox, the middle and 
hind coxe entirely, the tip of the femora, and the inner side of the tibiz rufous; bristles of the legs long, 
but not numerous. Tegule and wings brownish; a dark shadow covers the mediastinal cell and is 
extended over the small cross-vein ; a similar shadow borders the posterior cross-vein ; the apical half of 
the costa and the whole tip of the wing are somewhat obscure; the costa, from the base to the costal 
spine (at the end of the auxiliary vein), is beset with short bristles; apical cross-vein distinctly concave, 
its end parallel with the third vein ; posterior cross-vein straight. 
Hab. Costa Rica, Volcan de Irazu (Rogers). 
A single female specimen. 
DEXIOSOMA. 
Dexiosoma, Rondani, Dipt. Ital. Prodr. i. p. 85 (1856). 
Front broad; face perpendicular, not carinated in the middle; cheeks moderately large, with weak hairs ; 
in the femate, close to the frontal bristles, two orbital bristles ; oral margin retracted ; vibrissal swellings 
nearly parallel; vibrisse inserted at a considerable distance above the oral margin and some other 
bristles just at the margin. Antenne inserted above a line drawn through the centre of the eyes; third 
joint longer than the second ; arista plumose. Proboscis short and thick, retractile, with distinct terminal 
lips ; palpislender. Abdomen elongate-oval or elliptical, with only marginal macrochecte. Legs elongate ; 
hind tibiee with bristles of unequal length. Wings with a costal spine ; curvature of the fourth vein angular, 
with an appendage ; apical cell opened at a short distance before the wing’s tip; posterior cross-vein 
beyond the middle between the small cross-vein and the curvature of the fourth vein. 
1. Dexiosoma vibrissatum, sp. n., \. (Tab. V. figg. 13; 18 a, head.) 
Cinereous ; thoracic stripes, first abdominal segment, hind borders of the other segments, and legs black ; 
antenna, palpi, and terminal lips of the proboscis rufous. 
Length 10°5 millim. 
Front broader than the eyes, greyish; frontal band brown, as broad as the lateral portions ; frontal bristles 
rather strong; face and cheeks with white and rufous reflections; cheeks under the eyes nearly 
equalling the longitudinal diameter of the eyes; vibrisse much above the oral margin, two other 
bristles just at the margin, and some long bristly hairs along the lower part of the head. Antenne 
rufous, much shorter than the face; third joint three times as long as the second; arista rufous, rather 
thick, and densely plumose. Proboscis short, its large terminal lips and the small palpi rufous. Thorax 
and scutellum cinereous ; thoracic dorsum with four black stripes—the intermediate ones very distinct, 
convergent in front, and continued somewhat behind the transverse suture, the lateral stripes broader, 
less defined and reaching the base of the thorax ; scutellum flattened. Abdomen elliptical, the segments 
of nearly equal length; first segment black, the following segments greyish, with well-defined black 
hind borders; the grey colour on the sides has white reflections; the black borders occupy nearly 
half the length of the segments; strong macrochete are on the hind margins of all the segments. 
Legs black ; front femora with a row of bristles on the upper- and undersides; middle and hind femora 
with bristles on the underside only ; all the tibize with several long bristles; tarsi a little longer than 
the tibie; foot-claws and pulvilli slightly elongate, the pulvilli yellowish. Tegule whitish. Wings 
brownish-grey ; small cross-vein under the centre of the mediastinal cell and before the middle of the 
discal cell; apical cell narrowly opened at a short distance before the wing’s tip; curvature of the fourth 
vein rectangular and with a small appendage ; apical cross-vein concave ; posterior cross-vein nearly 
‘straight. 
Hab. Mexico, Teapa in Tabasco (H. H. Smith). 
A single male specimen. 
