Holcaspis Arizonica, n. sp.– Gall globular, 9 mm. diam, pale ochreous, not shiny, attached to the base of the petiole of a leaf of Quercus Arizonica, Sargent. There is a projecting point next to the place of insertion. Within, the gall is brown, fibrous, moderately dense, at least dithalamous.

Fly emerging April 19, two females. Body 3½ mm. long, wings 3⅔mm; antennæ 2 mm., 15-jointed, joint 3 considerably the longest. Length of joints in μ: (3·) 360, (4·) 240, (5·) 200, (15·) 170. The joints, especially the apical ones, with fine longitudinal ridges, between which are rows of minute punctures. Head ferruginous; thorax and abdomen piceous; margins of mesthorax, and two spots on scutellum, dull ferruginous; legs bright ferruginous; anterior tibiæ with an apical projection' anterior tibial spurs bent; claws of all the legs falciform, with a large triangular basal tooth.