Tongue dark brown; basal joint of the palpi, and the second joint externally, and on the under surface, dark brown; upper surface pale ochreous; tip white; third joint dark ochreous, tipped with dark brown. Head pale bronzy brown, with purplish reflections, each scale tipped with white. Sides of thorax and base of the wings ochreous yellow, extending along the costal portoin of the wings, gradually narrowing to about the middle of the costa.

Microctonus Agilis.N. sp–♂. Piceous, shining; clypeus and mandibles testaceous; palpi whitish; antennæ longer than head and thorax, slender, fuscous, basal third pale; pleura beneath, rufo-piceous; tegulæ whitish; wings hyaline, iridescent; nervures and stigma fuscous, the latter large, lanceolate; marginal cell longer than stigma, lanceolate; legs, ineluding coxæ, pale honey-yellow, extreme tips of posterior tibiæ dusky; abdomen smooth, shining, depressed, first segment tinged with rufo-piceous, gradually dilated to apex. Length .10 inch.

This genus comes next to Smicra, which has the greatest development of the peculiar characters of the family Chalcididae, such as the compact antennæ, the robust body, the large quadrate prothorax, and the much dilated hind thighs. In all these characters this family agrees with Leucospidae, from which it totally differs in the structure of the abdomen, and the two families have a supremacy of structure which is not wholly shared by any other in the tribe Chalcididae.