1914] Knab—Review of our Species of Trigonometopus 125 
In this species the ocular margins converge slightly anteriorly 
while in the two species which follow they are distinctly divergent; 
beyond the bulging eyes the frons is not markedly broadened, as 
is the case in the other species. The head is also slightly shorter 
in the portion beyond the eyes. In the single specimen the head 
is somewhat distorted, nevertheless the differences from 7. albi- 
frons, the species it most resembles, are obvious and abundant. 
Trigonometopus albifrons sp. nov. 
Male and female: Frons creamy white, very broad, widening anteriorly, a large 
dark. brown spot densely clothed with black hairs laterally before eyes, scattered 
black hairs anteriorly diminishing to behind the middle; occiput dark brown along 
posterior margins of eyes to the cheeks, a dark streak from the eye along the lower 
margin of the cheek, face white, nearly flat. Antenne whitish, the third joint 
tinged with ferruginous, compressed beyond its base, in profile broad and rounded; 
arista very long, pale near base, black beyond. Thorax narrow; mesonotum broadly 
blackish brown at the sides, a median yellowish zone occupying nearly half its 
width and divided by two ill-defined dark stripes into three pale longitudinal stripes. 
Seutellum blackish brown, with a narrow median and less distinct lateral yellowish 
stripes. Pleurz pale yellowish, infuscated on the mesosternum. Abdomen dor- 
sally black, with pale lateral incisions and a median yellowish stripe extending its 
entire length; venter pale. Legs pale yellowish, the bristles black; tarsi very 
slightly infuscated. Wings rather broad, the costal region to the middle of the 
submarginal cell pale yellow, semi-opaque and with the veins pale; posterior portion 
of wing tinged with grey and with all the veins behind the second black, a darker 
shade about the cross-veins and broadly along the third vein, particularly distally 
where it is abruptly produced to the anterior margin at the tip of the second vein. 
Halteres pale, with infuscated knobs. Length: Body about 4.2 mm., wing 
3.5 mm. 
San Marcos, Nicaragua, 2 specimens (C. F. Baker); Cacao, 
Trece Aguas, Alta Vera Paz, Guatemala, 30 March, 1906, one 
specimen (Schwarz and Barber). 
Type: Cat. No 18481, U.S. Nat. Mus. 
The specimen from Guatemala differs in some respects. On 
the wings the anterior expansion of the dark shade reaches the 
costa before the end of the second vein, thus involving the tip of 
the marginal cell; the portion of the second vein within the dark 
shade is black. I attribute no significance to this difference, as 
the two specimens from Nicaragua, which are surely conspecific, 
show variation in this respect. In one the dark shade reaches 
the costa at the tip of the second vein, in the other the pale costal 
zone extends a short distance beyond the end of the second vein. 
