208 DIPTERA. 
and a little beyond the middle of the discal cell; posterior cross-vein straight, in the middle between the 
small cross-vein and the curvature of the fourth vein. 
Hab. Mexico, Medellin near Vera Cruz (1. H. Smith). 
A single specimen, apparently a female. 
MYOTHYRIA, gen. nov.* 
Front scarcely prominent, moderately broad ; frontal bristles descending on each side in a single row nearly as 
far as the second antennal joint ; face perpendicular or slightly inclined; facial ridges without bristles ; 
cheeks rather narrow. Eyes bare. Antenne shorter than the face; third joint at least twice as long.as 
the second; arista bare. Abdomen elliptical or elongate-oval; first segment shorter than the second ; 
second and third segments in one species with discal and marginal, in the others only with marginal, 
macrochete. Legs rather elongate and bristly. Wings longer than the abdomen, sometimes with a very 
small costal spine; curvature of the fourth vein angular or arcuated ; apical cell closed at or a little before 
the tip of the wing; posterior cross-vein in or beyond the middle, between the small cross-vein and 
the curvature of the fourth vein. 
If attention is paid to the relative length of the antennal joints and to the position 
of the posterior cross-vein, Myothyria cannot be confounded with other genera having 
bare eyes and the apical cell closed at the wing’s margin. In Frivaldskyia the third 
antennal joint is much longer than in Myothyria; in Microsoma and Clista the third 
antennal joint is not longer than the second ; in Petagnia the posterior cross-vein is 
nearer to the small cross-vein. From Degeeria (some species of which have a closed or 
nearly closed apical cell) the present genus differs by the absence of bristles on the 
facial ridges. 
In this genus I include the following three species :— 
1. Second and third abdominal segments with discal and 
marginal macrochete; curvature of the fourth vein 
arcuated . . . . we we ww ee Ctrichosoma, v. d. Wulp. 
Second and third abdominal segments with marginal 
macrochetze only; curvature of the fourth vein 
angular . . 1. ww ee eee ee 
2. Posterior cross-vein curved; larger species (5°5-7 aan / 
millim.) . . ......., . . ‘ . . majorina, v. d. Wulp. Ty io [Cow Alo] 
Posterior cross-vein straight; smaller species (3 : s 
millim.) . . 2... 2. es ee se.) . «68. degeerioides, v. d. Wulp. 
1. Myothyria trichosoma, sp. n.,¢. 
Yellowish-grey ; frontal band, four thoracic stripes, hind borders of the abdominal segments, antenne, and 
legs black ; palpi rufous; abdomen with discal and marginal macrochete. 
Length 3-5 millim. 
Front yellowish, a little broader than the eyes; frontal band narrower than the lateral portions ; frontal bristles 
descending as far as the end of the second antennal joint; face and cheeks whitish. Antenne nearly as 
* pva (to close); Oupés (cell). 
