MYOBIA. 137 
Greyish-cinereous. Head whitish; front slightly prominent, distinctly broader than the eyes; frontal band 
dark brown, narrower than the lateral portions ; frontal bristles few in number, two or three of them 
beneath the root of the antenne; face a little inclined; cheeks broad; eyes not descending to the 
vibrissee, which are inserted on the oral margin. Antenne rufous, much shorter than the face; second 
joint elongate, bristly; third joint as long as the second, somewhat infuscated towards the tip; arista 
black, thickened in its proximal half. (The proboscis and palpi are retracted in the oral cavity, the 
former is apparently black and the latter seem to be rufous.) The stripes on the thoracic dorsum are 
interrupted at the transverse suture; the intermediate ones are linear and the outer ones in the form of 
small trigonal spots. Abdomen conical ; first segment a little shorter than the second; the black hind 
borders are rather narrow, those of the second and third segments being interrupted at the middle; the 
anus is slightly rufous; long macrochete are on the hind margin of the second and following segments. 
Legs brown, the coxe and part of the femora with grey tomentum; the knees and the underside of the 
femora towards the tip rufous; front tibise with short, the middle and hind tibie with longer bristles. 
Tegule whitish. Wings greyish-hyaline, somewhat brownish along the costa; small cross-vein on the 
middle of the discal cell; curvation of the fourth vein with a right angle; apical cross-vein concave ; 
posterior cross-vein slightly curved. 
Hab. Mexico, Chilpancingo in Guerrero 4600 feet (H. H. Smith). 
A single female specimen. 
9. Myobia diadema. (Tab. IV. fig. 2.) 
Dexia diadema, Wiedem. Aussereur. zweifl. Ins. ii. p. 882. no. 24°. 
Head yellowish-white ; front in the male not so broad as the eyes and still narrower behind, in the female 
somewhat broader ; frontal band narrow, black or brownish-black ; frontal bristles weak, not descending 
beneath the root of the antenne ; vibrissee inserted at a little distance above the oral margin, which is 
very slightly prominent. Antenne rather slender; basal joints rufous; third joint not fully three times 
as long as the second, brown or blackish, with a rufous base, sometimes almost wholly of the latter 
colour ; arista pubescent, thin, scarcely thicker in its proximal half. Proboscis long and slender, shining 
black, rufous towards the tip; palpi pale rufous, slightly thickened, sometimes a little infuscated at the 
tip. Thorax covered with a greyish or yellow tomentum, sometimes with indications of dark lines; 
pleurs whitish-grey ; scutellum rufous. Abdomen—of the male elongate-conical, yellowish-rufous, slightly 
transparent ; on the hind margin of the second and third segments a small trigonal black dorsal spot; in 
most specimens the third and anal segments have laterally a similar spot, in others the third segment has 
a narrow black hind margin ; the black markings are more or less distinct, but seldom totally absent ; 
sometimes a white reflection appears on the front margins of the segments ; the macrochete are few in 
‘number and only on the hind margin of the second and following segments ;—of the female more 
elliptical, of the same colour, but usually less transparent, and with similar black markings and macro- 
chete. Legs rufous, the tarsi black, the hind tibie brown; the front tarsi in the male twice, in the 
female one and a half times as long as the tibie ; bristles proportionately short and weak ; foot-claws and 
pulvilli elongate in the male, very short in the female, the pulvilli yellow. Tegule yellowish. Wings in 
the male in most examples much longer than the abdomen, greyish-hyaline, usually with a dilute brownish 
tint at the end of the second vein; curvation of the fourth vein with a blunt angle; apical cross-vein a 
little concave, sometimes nearly straight ; posterior cross-vein sinuous.( ¢ ) or very slightly curved (9 ). 
The specimens are very variable in size (5-9 millim. in length); the males are usually larger (6°5 millim. or 
more) than the females (5-6 millim.), but this is not a general rule. 
Hab. Mexico, Amula 6000 feet and Xucumanatlan 7000 feet, both in Guerrero, 
Cuernavaca in Morelos, Atoyac and Medellin in Vera Cruz, Teapa in Tabasco (#. 4. 
Smith), Temax in North Yucatan (Gaumer) ; Costa Rica, Cache (Rogers).—Braziu !. 
This species seems to be very common in Central America, whence we have received 
BIOL. CENTR.-AMER., Dipt., Vol. II., May 1890. t 
