MANN: THE ANTS OF BRAZIL. 463 
petiolar node shallowly, densely rugulose. Posterior surface of node 
and the gaster finely, densely punctate, the latter regularly granulose. 
Body thickly covered with short, fine, erect pile. Antennae mi- 
nutely pubescent. 
Color black; antennae and legs ferruginous. 
Described from a single worker taken at Porto Velho. In color 
and general form, as well as in sculpture D. varians resembles D. 
lamellosus, from which it differs in the shape of the mesonotum. In 
the latter species this is transversely oval, while in D. varians it is 
distinctly longer than broad, with a faintly crenulate border. Dolicho- 
derus varians is also much more thickly pilose. The other closely 
related species, D. laminatus, has much narrower pronotal spines and 
finer sculpture throughout. 
160. Dolichoderus (Monacis) tristis, sp. nov. 
Plate\2, fig. 17. 
Worker. Length 4.5 mm. 
Head, excluding mandibles, a little longer than broad, narrowed 
in front, with slightly rounded sides and nearly straight posterior 
border; occipital corners broadly rounded. Clypeus rounded, the 
anterior border concave at middle. Frontal carinae nearly straight, 
subparallel, extending to opposite middle of eyes. Eyes small, feebly 
convex, located in front of sides of head a little behind the middle. 
Mandibles short and thick. Antennae short, the scape curved, 
thickened and flattened toward apex, extending less than one third 
its length beyond the occipital corners; funicular joints subequal in 
length, the first constricted at base, joints 3-10 cylindrical, about one 
and a half times as long as broad; joint 10 as long as broad; apical 
joint twice the length of penultimate. Pronotum transverse, nar- 
rower than head; the short neck transversely depressed; sides convex, 
acutely margined, the spines short and stout. Mesonotum trans- 
verse, sides margined. Epinotum campanulate, unarmed, flat above, 
the margin projecting laterally and behind; surface of basal portion 
rounded. Petiole from above transverse; in profile thicker than long, 
flat above, straight in front, concave behind; the posterior apical 
border with a short, thick, triangular spine which projects upward 
and backward; posteroventral surface extended into a triangular 
process. Gaster short and thick, considerably broader than the 
thorax. 
