1952] 
Gregg — Formica opaciventris 
15 
equal to about % of their lengths. Eyes of the usual shape 
(oval), rather flat, and situated posterior to the middle of 
the head. Mandibles triangular, with 5 to 6 more or less 
distinct teeth, and no denticles along the basal border. 
Frontal carinae short (about twice as long as the diameter 
of the antennal fossae), straight, and strongly divergent. 
Ocelli distinct. 
Thorax somewhat narrower than the head, dorsum al- 
most flat in profile. Scutum broadly egg-shaped with 
prominent parapsidal furrows; scutellar sclerites well de- 
veloped laterally, obsolete medially; postscutellum trape- 
zoidal, moderately elevated above the metanotum. Epinotum 
rounded dorsally and laterally; basal face short and the 
declivity long and sloping, with the angle between them 
indistinct, indicated only by the greatest convexity of the 
epinotal profile. Petiolar scale extremely broad with 
straight sides, giving it a decidedly quadrate appearance, 
especially when viewed from the front; slightly convex 
anteriorly and flat posteriorly ; superior border sharp, 
faintly emarginate in the middle, and expanded into small 
spatulate lobes at the upper corners of the scale. Spiracular 
openings on the petiole form prominent denticles on the 
sides near the base of the scale. Wings are absent on the 
specimen, but ragged fragments of the bases of both an- 
terior wings and the left posterior wing present. Abdomen 
oval and of the usual formicine shape. 
Head opaque, except the frontal area and corners of the 
clypeus which are somewhat smooth and shining. Mandibles 
striated but otherwise shining. Thorax subopaque, rather 
faintly shining on the mesonotum and near the sutures. 
Petiole and gaster subopaque, the surfaces less heavily 
shagreened so that their shiny appearance is not com- 
pletely obscured. 
Erect hairs present on the frons, clypeus, vertex, man- 
dibles, top of pro-, meso-, and metanotum, posterior face 
and peduncle of the petiole, anterior margin of gaster, 
venter, dorsum of last three gastric segments, coxae, and 
a very few on the femora. Tibiae with graduated bristles 
on the flexor surfaces. The scutellum has on each side a 
