56 DIPTERA. 
7. Mystacella tessellata, sp.n.,¢ 9. 
Greyish-cinereous ; antenne, legs, frontal band, and four stripes on the thorax black; palpi pale rufous ; 
scutellum testaceous ; abdomen with blackish reflecting spots, in the male laterally testaceous ; anal 
segment rufous. 
Length 7:5 millim. 
Head yellowish-grey with brown reflections ; front in the male much narrowed behind (more than in the 
preceding species), in the female broader than the diameter of the eyes; frontal band over its whole 
length of equal breadth; frontal bristles short, descending to the number of four beneath the root of the 
antenne: cheeks bare; eyes densely pilose. Antenne much shorter than the face; third joint rather 
broad, twice as long as the second. Thorax whitish-grey, with four black stripes; in the male usually 
with a conspicuous fifth or median stripe; the portion before the scutellum bluish in tint. Abdomen 
grey (laterally testaceous or rufous in the male), with irregular dark brown or blackish reflecting spots 
and an interrupted black dorsal line; third segment with a narrow white front margin ; anal segment 
rufous, with grey or yellowish reflecting spots, and densely beset with black hairs; in the female two long 
macrochsete on the hind margin of the second segment ; in both sexes there is a row of similar macrochate 
on the hind margin of the third segment. Legs black; femora with many bristles, which are regularly 
arranged on the front pair; front tibia outwardly with a row of bristles; middle tibia with some long 
and robust bristles; hind tibie with the outer bristles almost fringe-like, in the female with a longer 
bristle beneath the middle; foot-claws and pulvilli elongate in the male; pulvilli greyish. Tegule 
whitish. Wings greyish-hyaline ; small cross-vein before the middle of the discal cell; apical cross-vein 
very slightly concave ; posterior cross-vein distinctly curved. 
Hab. Mexico, Amula 6000 feet, Xucumanatlan 7000 feet, and Omilteme 8000 feet, 
all in Guerrero, Cuernavaca in Morelos (H. H. Smith). 
Several male and two female specimens. 
A male example, captured by Mr. Smith at Venta de Zopilote (Guerrero, 2800 feet), 
is of a much larger size (13 millim. in length), but agrees very closely with the descrip- 
tion given above; it has, however, the frontal bristles still shorter than in the normal 
specimens, and the outside of the hind tibie more densely fringed. Perhaps it may 
belong to a distinct species. 
The males of MW. tessellata bear a striking resemblance to W. rubriventris, but are recag- 
nizable by their more prominent front and the eyes not descending beneath the vibrisse. 
8. Mystacella postera, sp. n., 2. 
Yellowish-grey ; head and anal segment ochraceous; thorax with four black stripes; hind margin of the 
scutellum rufous; abdomen with blackish reflecting spots; antenne and legs black, the posterior tibie 
dark rufous ; palpi rufous. 
Length 8°5 miliim. 
Head bright ochraceous, partly with brown reflections ; front slightly prominent, notably broader than the 
eyes ; frontal band blackish, broad, but sometimes evanescent; frontal bristles widely remote from each 
other, on both sides descending in a curved row to beneath the second antennal joint ; above the vibrisse 
four shorter bristles which mount on to the facial ridges; eyes short-haired. Antennx black ; second 
joint bristly ; third joint two and a half times longer than the second; arista thickened on the proximal 
half. Proboscis black; palpi rufous. Thorax grey, with four distinct broad black stripes; scutellum 
cinereous, with the hind margin pale rufous. Abdomen ovate, grey, with irregular blackish reflecting 
spots; the sides yellowish; anal segment bright ochraceous; two dorsal macrochetz on the hind 
margin of the first and second segments; a row of macrochete on that of the third segment; anal 
segment with several macrochete. Legs black, the femora with grey reflections; middle and hind tibia 
dark rufous ; middle tibie outwardly with three long bristles; hind tibie with several bristles of unequal 
