The general shape of this gall is very different from that of most of the species of Disholcaspis, but the location and character of the larval cell is typical for that genus. The insect is a true Disholcaspis.
Beside the two cotype adults from normal galls, I cut from a very small cotype gall a female which is in all respects like the cotypes but that it is generally darker and is very remarkably smaller in size, being only 1.7 mm. in length. I do not recall that I have ever before found an individual of the gall-wasps varying so from the average of length for the species.
Practically every one of the galls I have seen had large exit holes, indicating that a large number of the wasps had reached maturity and had emerged.
Disholcaspis plumbella, new species
Plate XXVI, Figures 34 to 36
Female.—Almost entirely bright reddish brown; antennæ 14-jointed; parapsidal grooves indistinct; anterior parallel lines close together; lateral lines prominent; second segment of the abdomen tongue-shaped. Head: light reddish brown, small spots near the ocelli and the tips of the mandibles dark brown; very finely granular-rugose, hairy; antennæ 14-jointed, joints one and two stout, third joint long and slender, whole antenna quite uniformly reddish brown, pubescent. Thorax: bright reddish brown, only very slightly darker on the parallel lines and the lateral lines; mesothorax much elevated and rounded, as broad as long, finely coriaceous, covered with rather long, yellowish hairs which are shortest and less dense on the midline; parapsidal grooves not very distinct, extending half-way to the pronotum; median groove mostly absent; anterior parallel lines prominent but not smooth, unusually close together, extending more than half-way to the scutellum and diverging slightly posteriorly; lateral lines prominent, free of hairs, not smooth, extending from the scutellum half-way to the pronotum; scutellum finely rugose, hairy, with two large foveæ at the base, shining, but somewhat rugose. Abdomen: rufous, darker posteriorly, shining but finely punctate, the sides entirely covered with rather long hairs, the second segment tongue-shaped, i. e., produced dorsally. Legs: coxæ of the same color as the thorax. Wings: clear, the veins yellowish brown. Length: about 3 mm.
Galls.—Small, brown, bullet-galls (Figs. 34 to 36), bearing a sharp, projecting point at the apex. Monothalamous. Entirely spherical, 9 mm. or less in diameter, yellowish or reddish brown, the surface of the dried galls shrivelled but essentially smooth, bearing a sharp point at the apex which is about 1.5 mm. long. Internally the gall is filled with a loosely granular, yellow tissue; the larval cell is hardly distinct from this surrounding tissue. On twigs of Quercus dumosa.
Range.—California: San Diego County (D. Cleveland Coll.).
Cotypes.—A female holotype and three gall cotypes in the collection of the Museum of Comparative Zoology and in the author's collection. The galls were collected in October 1875. The adult which I cut from one of these cotype galls is broken and imperfect.
