26 o 
Psyche 
[September 
rims (see Fig. 5). Clypeus, except for the small raised median 
portion, impressed, very narrow and not distinctly demarcated behind, 
its anterior border shallowly but broadly concave, unarmed. The 
basal part of the labrum forms a straight line within the clypeal 
concavity, and bears a row (actually backed by a second row) of 
peg-like teeth that seem at first sight to spring from the clypeal 
margin. These teeth fill the narrow space between the clypeus and 
the normally closed mandible. Mandibles short, gently curved, and 
linear, with bidentate apex and a few blunt, spaced teeth on apical 
half of inner border. Labrum broader than long, sides converging 
distad ; apex broadly emarginate; extensor surface with two irregular 
rows of peg-like teeth (or modified hairs) on basal half. Maxilla 
simplified from form of Amblyopone pallipes (see Gotwald, 1969), 
without galeal comb, and galeal crown smoothly continuing the 
dorsal galeal margin; maxillary palpus 2-segmented. Labium appa- 
rently without paraglossal lobes ; setae of subglossal brushes tapered 
to apices; labial palpi 2-segmented. 
Truncus (— alitrunk, = thorax + propodeum) long and slender, 
consisting of a convex, immarginate pronotum into which is flexibly 
fitted a slightly longer oblong portion consisting mainly of propodeum, 
meso- and metathorax; mesonotum reduced to a narrow, depressed 
transverse strip largely covered by posterior edge of pronotum except 
when pronotum is flexed downward. Propodeal dorsum almost flat 
(weakly convex), immarginate but with pleura perpendicular; de- 
clivity strongly convex, immarginate and unarmed, overhanging lower 
part and orifice. Bulla of metapleural gland conspicuously outlined 
through cuticle, subcircular; propodeal spiracle contiguous with it 
anteriad. Coxae nearly the same size (anterior coxa largest) ; 
femora short and strongly incrassate toward their middle; tarsi 
short, slender at base but gradually becoming thicker to near their 
apices. Tibial spurs 1, 2, 2, the middle and posterior legs each with 
one large, broadly pectinate inner spur and a smaller, more slender, 
sparsely pectinate outer one. Metatarsus of anterior legs strongly 
Plate 1. A pomyrma stygia, worker of the small kind (type nest series), 
scanning electron micrographs by H. E. Hinton. A, head and part of truncus 
in oblique lateral view, X 43. B, head in oblique dorsal view, X 49. C, 
dorsal view of pronotum and adjacent structures, X 104; note reticulation 
of cervix and striation of mesonotum. D, back of head and cervix, dorsal 
detail. X 248. E, lateral view of pronotum and adjacent structures, X 83. 
F, oblique dorsal view of posterior part of dorsal pronotum, mesonotum, 
and propodeal dorsum, looking caudad, X 104. 
