Type specimens at Ohio State University.

16. Cecidomyia sp.

On leaf, under side, greatly depressed with central, prominent nipple, 3-5 mm. dia. 1½-2½ mm. thick (vertical dia.) not including nipple. Light green, smooth. Firm fleshy with central sub-spherical larval chamber whose wall is differentiated from the surrounding tissue. Apical canal through nipple evident. This gall first reported and illustrated by Thompson.

Thompson, Illus. Cat. Am. Ins. Galls. 1915. p. 56, pl. 13, Fig. 228.

A most interesting variant of this form is illustrated in [Fig. 16a]. If it were not for the large number of intermediate forms found, this one would easily be considered distinct. The region of the chamber surrounded by thick walls has been much reduced, so that only a circular area about the upper part of the chamber has the thick wall projecting from it. This new condition results in the formation of a definite saucer-shaped structure on the distal end of the gall. In some specimens the structure was no longer saucer-shape, but by the ingrowth of the edges it was assuming a spherical form, developing a two-chambered gall. It is natural to suspect that this may have been the mode of origin of the four-double-chambered galls described elsewhere in this paper. That, however, is entirely problematic.

17. Caryomyia periscoides Beut.

On leaf, underside, generally large, sub-globular galls. Younger ones appear like older, both often being found on same leaflet, 4-7 mm. diameter. Galls covered with a fine short yellowish to reddish pubescence, suggesting the texture of peach “bloom.” Walls very thick, firm fleshy, surrounding the central spherical cavity, pierced, however, at the distal end by the fine apical canal. Closely sessile on leaf, generally at side of principal vein. Collected on H. alba, glabra and ovata.

From Felt’s short description, Caryomyia antennata Felt, must have been taken from a similar gall.

18. Cecidomyia sp.