166 DIPTERA. 
' second joint prominent, with some bristles ; third joint oval, a little longer than the second; arista bare. 
Thorax and hind margin of the scutellum with rather weak bristles. Abdomen convex, broadly ovate, 
composed of four visible segments, a fifth segment being bent close to the venter; on the third and fourth 
segments some hairs, which can scarcely be called macrochete. Legs with weak bristles. Tegule large. 
Wings of the male unusually broad, the coste rounded; auxiliary vein short; first vein ending in a 
slightly elevated callosity almost in the middle of the costa; the second vein at its basal part very near 
the first, close to the costa outwardly but midway enlarged into a callosity just under the costal callosity ; 
the following veins, on the contrary, are pressed downwards ; the third vein is deeply arcuated, in con- 
sequence of which the subcostal cell is unusually broad in the middle; the subcostal cell has a longitudinal 
false vein or fold; the curvature of the fourth vein forms a right angle, and the apical cross-vein is 
slightly concave; the apical and discal cells are oblong and rather narrow, the former narrowly opened 
at or a little before the wing’s tip; the small cross-vein is on the middle of the discal cell, the posterior 
cross-vein on two-thirds of the apical cell. 
In the female the wings are more normal. 
1. Neoptera rufa, sp.n.,¢ 9. (Tab. IV. figg. 11,3; lla, wing; 11 4, head in 
profile; llc, head from in front, ¢: 12, wing; 12a, head from in front, ? .) 
Length 6 millim. 
Ferruginous, including the antenna, legs, and tegule ; the tarsi very slightly infuscated ; the foot-claws and 
pulvilli short in both sexes (but the male is recognizable, apart from its abnormal wings, by the narrower 
front). Wings subhyaline; the veins near the costa (and in the male also the callosities) yellowish ; the 
small cross-vein slightly infuscated. 
Hab. Mzxico, Vera Cruz, Teapa in Tabasco (H. H. Smith). 
A male specimen from the former, a female from the latter locality. 
CENOSOMA, gen. nov.* 
Head nearly hemispherical; front of the male narrower behind, of the female very broad ; frontal bristles 
weak, not descending beneath the root of the antennz ; ocellar knob very conspicuous; face perpendicular, 
- without bristles ; oral margin not prominent; cheeks broad ; eyes bare; no distinct vibrisse, but several 
short bristles at the oral margin. Antenne as in Neoptera. Thorax and hind margin of the scutellum 
with weak bristles. Abdomen convex, elongate-oval, transparent, with marginal macrochete but without 
discal ones on the second and following segments. Legs rather short, with weak bristles ; foot-claws and 
pulvilli not elongate in the male. Tegule large. Wings with a costal spine; apical cell narrowly opened 
at the wing’s tip; second vein at nearly the same distance from the costa and from the third vein ; small 
cross-vein on the middle of the discal cell; posterior cross-vein in the middle between the small cross-vein 
and the curvature of the fourth vein. 
This genus is closely allied to Neoptera; the shape of the head is very similar; the 
abdomen, however, is somewhat more elongate and its macrochete are more normal ; 
moreover, the wings are not dilated in the male, and the second vein is in the usual 
position (not close to the costa). 
* xevos (empty), cdma (body). 
