Female.—Head: Not quite as wide as thorax, hardly widened behind the bulging eyes; black, mouth-parts bright piceous; coriaceous, finely rugose and scatteringly hairy on the face. Antennæ brown, yellowish basally; densely hairy except on the first two segments; 14 (?)-jointed; third segment not much longer than fourth. Thorax: Piceous black to black; smooth and shining, only microscopically coriaceous anteriorly and laterally; parapsidal grooves deep, continuous to the pronotum, gradually diverging anteriorly, gradually converging toward the scutellum; median groove lacking; anterior parallel lines and lateral lines practically lacking; scutellum black, elongate, rugose, hairy, an arcuate depression at the base, deep, smooth, not forming foveæ; pronotum piceous black, rugose, rugoso-aciculate laterally; mesopleuræ black, rugose, very sparsely hairy, aciculate, the central area smoother, shining. Abdomen: Piceous black; smooth and shining, microscopically punctate, sparingly hairy at the base laterally; produced dorsally, the second segment covering about half the area, segments two to four with the edges at an angle of 45°; ventral spine short, lighter in color, sparsely hairy; ventral valves hairy, at a 45° angle. Legs: Yellow-brown, the coxæ piceous, the tips of tarsi brown; tarsal claws simple. Wings: Clear, minutely hairy, ciliate on margin; veins brown, subcosta, radius, and basalis heavy; areolet moderately small; cubitus hardly reaching basalis; radial cell long and narrow, open, the second abscissa of the radius straight, the first abscissa slightly angulate, without a projection, slightly infuscated. Length: 2.0–2.5 mm.
- Male.–Differs from the female as follows: antennæ entirely brown, 15-jointed; thorax more elongate; abdomen very small, narrow, rather long-pedicellate; legs darker brown.
- Galls (Pl. XXIV, Figs. 15, 16).—Small, inflated capsules in the leaf-blade. Monothalamous. Spherical, 3.–5. mm. in diameter, about smooth, leaf-green when fresh, soon paling, finally drying yellow-brown. Walls thin, a thin-walled larval cell, about 1.5 mm. in diameter, is connected with the outside wall by a tangle of dense, but not definitely branched fibers. In the leaf-tissue, projecting about equally on either side, usually near the edge of very young leaves of Quercus Douglasii.
- Range.—California: Three Rivers, Redding.
- Types.—Five females, six males, thirty-eight galls, labelled Three Rivers, California; March 23, 1920; Kinsey collector. The adults are all imperfect. Holotype female and paratype adults and galls in the collections of The American Museum of Natural History; paratype adults in the collection of the author; galls at Leland Stanford University and the U. S. National Museum.
These galls develop early on the unfolding leaves, looking like small air-bubbles blown in the tissue. The galls were always very new and fresh when gathered, but were also practically mature. The development of this generation of the species must be a matter of only a month or two; the other generation is unknown. The adults were maturing, had not emerged, but did emerge at some date later than the dates of collecting the galls: March 23 at Three Rivers, and April 2 at Redding. Of 23 adults, 13 were females. This species resembles Andricus palustris form palustris (Osten Sacken) of the black oaks of the eastern part of the United States, and it might prove desirable to consider the two as varieties of one species. Morphologically the two are very similar, even
