While on a short visit in northern Maine during the summer of 1946, I collected a new and interesting ant of the Microgyna group of the genus Formica. The description follows below:

Formica dirksi sp. nov.

Deälate queen, total length 5.1 mm. Head, maximum width through eyes 1.2 mm., at base of mandibles 0.78 mm., length to anterior border of clypeus 1.3 mm. Thorax, Weber's (1938: 155, footnote) measurement 2.1 mm. General characters of the Microgyna group. Mandibles 7-toothed. Clypeus evenly rounded in front, with uneven surface and carina just barely distinguishable as a line anteriorly, but becoming a low blunt ridge through the mid-region and disappearing posteriorly. Head, excluding mandibles and eyes, somewhat longer than broad; narrower in front than in behind, with posterior corners evenly rounded, posterior border and sides slightly convex. Antennae of medium size, scape slightly stouter apically than basally, bent slightly and gradually in basal half, joints 2 and 3 of funiculus distinctly longer than broad; the apical joints only slightly longer than broad. Frontal area distinct, subtriangular, and about twice as broad at base as high. Frontal carinae diverging posteriorly, about as long as width of frontal area. Eyes black, more or less oval, strongly convex, remote from mandibular insertions and close to posterior corners of head. Ocelli medium-sized, round, white and forming an isosceles triangle with a base, which is situated posteriorly, equal to 0.24 mm. Ratio of base to the shorter sides is 10 to 7.