On leaf, generally on upper side, balloon-shaped gall, 3-5 mm. high, 3-4 mm. wide. Terminal nipple arising from slight apical depression. Greenish-brown or sometimes varying toward a very dark purplish tinge, its peculiar color being very constant and characteristic. The surface is dotted over with short, swollen glandular hairs. Trichomes sometimes projecting slightly from apical pore. Walls very thin. Galls attached to short, stout process of the leaf, to be seen only in median, vertical section. Surface of leaf on side opposite the gall not raised. Never numerous on leaflet. Closely related, if not identical, with _C. caryae_ O. S. See No. 20. Observed on _H. glabra_, in Hocking County, Ohio, July. 26. =Caryomyia tubicola= O. S. On leaf, under side, cylindrical with rounded distal end standing erect from the cup-like base embedded in the leaf blade. 4-6 mm. high, generally very close to 5 mm. 1 mm. dia. Body of gall, yellow to brown in color, distal end reddish to brown, at length almost black. Basal cup, greenish yellow to dark purple. Cylindrical part of gall smooth as though polished. Gall attached to the cup only at its central basal part. Before the end of summer the tube-like portion breaks away with its enclosed larva. On the side of the leaf opposite the gall its position is indicated merely by a dark discoloration. Very common on different kinds of hickories. Osten Sacken, Lowe’s Monogr. Dip N. Am. Pt. 1, p. 192, 1862. Felt, Rept. Ins. N. Y. 1907. pp. 382, 388, pl. 37, Fig. 5. Felt, “Caryomyia tubicola” Jour. Econ. Ent. 4:456. 1911. 27. =Cecidomyia= sp. =Cecidium= nov. Leaf, under side, arising from a shallow cup-like structure. Shape of a slender horn, slightly curved, 5-7 mm. long, 1¼ mm. wide at base. Light green at base, changing to yellow, the distal ⅔ of the gall a deep brown. No demonstrable opening at the end. Walls thin. Surface smooth, under lens minute longitudinal striations evident. Very little discoloration on the upper side of the leaf to mark the location of the gall beneath. Resembles _Caryomyia tubicola_ O. S. but is certainly a different species. Collected in Hocking County, Ohio, July, on _H. alba_. Type specimens at Ohio State University. 28. =Cecidomyia= sp. =Cecidium= nov. On leaf, generally upper side, delicate, small, sub-cylindric galls, standing erect, 2-2½ mm. high, less than 1 mm. wide, constricted proximally to the slightly flaring base. Distal end marked off by a circular ridge, in the center of which is a rounded nipple. This latter turns dark early. Gall light green, at length turning brown. Arises from intervenal areas between the smaller veins. On the under side of the leaf the gall above is indicated by a minute dark area. Attached to leaf by minute central pedicel. Collected in Hocking County, Ohio, on _H. alba_ in July. Type specimens at Ohio State University. 29. =Cecidozoon= (Type undetermined.) =Cecidium= nov.