No. 414.] NESTS OF AMERICAN ANTS. 435 
Female. Length nearly 4 mm. 
Thorax more opaque, more distinctly rugose, and of a darker 
brown color than in the worker. 
Male (Fig. 3. Length 2.75-3 mm. 
Coloration brownish yellow like that of the worker; head, 
thoracic dorsum, abdomen, and the middle portions of the femora 
and tibia somewhat darker. Wings colorless, with very pale 
veins and stigmata. Hairs almost completely absent on the 
head and thorax, short and inconspicuous on the legs, long on 
the abdomen, but nowhere truncated at their tips. 
Mandibles striated, hairy, very small, not distinctly dentate, 
and far from meeting each other with their blades. Clypeus 
even in the middle with a few delicate longitudinal ruge. 
Head above longitudinally reticulate-rugose; ruga radiating 
backwards and laterally from the posterior ocelli as centers. 
Antenne 12-jointed ; scape scarcely as long 
as the three first joints of the flagellum 
taken together; first joint of flagellum very 
short, the others of uniform thickness but 
increasing gradually in rength towards the 
tip. Thorax rather smooth, indistinctly 
punctate ; parapsidal and other sutures 
very distinct ; metanotum with two very 
short rugose projections in the place of the 
spines. Dorsal projection of the petiole 
rounded, its posterior slope slightly concave, 
the anterior convex. Postpetiole hemispher- 
ical; abdomen very glabrous, somewhat 
less flattened than that of the worker. Fic. 3.— Leptothorax 
Leptothorax emersoni is to be assigned to — 777^ pigri 
the small group of North-American species comprising Z. mus- 
corum Nyl. (also recorded from Europe), Z. canadensis Proven- 
cher, with its variety yankee Emery, L. hirticornis Emery, and 
L. provencheri Emery. The workers of all these forms have 
I1-jointed antennz and a distinct meso-metanotal constriction. 
That the new species is perfectly distinct from all of these is 
