Cylindric-conic, sharply bent over against the leaf, attenuate distal part short, not recurved, 3½ mm. long. Smooth, white like ivory. Wall rather thick, hard. Base of gall in shallow saucer-like depression against the vein. Interiorly the distal end is choked with coarse trichomes. 10. =Cecidomyia= sp. =Cecidium= nov. Leaf, under side, distal ⅔ of gall dome-shaped with 3-many triangular sides, the flaring base resting on the proximal, constricted or saucer-shaped ⅓; 2-3 mm. high, 3-4 mm. wide. Tip attenuate, not sharp pointed, however. Light green to yellowish green, the tip darker, reddish to black. Surface smooth under lens. Larval chamber spherical, surrounded by sclerenchmya layer. This gall is very distinctive no other forms having the peculiar angular structure which it possesses. Not abundant. Collected at Gypsum, Ohio, August, on _H. microcarpa_. Type specimens at Ohio State University. 11. =Cecidomyia= sp. =Cecidium= nov. On leaf, under side, rather large conic gall, whose distal ½-⅓ constitutes a very slender apical process. Through this passes the fine canal leading to the depressed, sub-globular chamber in the proximal part of the gall. The galls are either erect or more generally tilted to one side, always arising from one of the larger veins. 5-8 mm. long, 2½-3½ mm. wide at base. Outline of the flaring sessile base generally angular. Attenuate distal portion turning dark early. Light greenish yellow to brown when old. Smooth. Walls of chamber thick. A slender probable variety of this is figured in 11a, pl. I. Collected in Hocking County, Ohio, on _H. alba_. July. Type specimens at Ohio State University. 12. =Caryomyia caryæcola= O. S. On leaf, under side, large galls with globular basal part extending into a point distally. Shape suggests that of a Prince Rupert’s drop. 4-7 mm. long. Surface very smooth, greenish to reddish tinged. Some show a definite blue color over the attenuate apical end. Walls of medium thickness, very firm. Somewhat similar to _C. sanguinolenta_ O. S. but differs from that gall in its larger size and much more attenuate distal end. Common on different hickories. Osten Sacken, Lowe’s Mongr. Dip N. Am. Pt. 1, p. 192. 1862. Felt, Jour. Econ. Ent. 4:456. 1911. 13. =Caryomyia sanguinolenta= O. S. On leaf, beneath, stoutly conical, varying in size from 1½ mm. to 4 mm. high. Tip erect or often bent to one side. Smooth, green to purplish-red and finally a brown when old. Attached to smaller veins by short pedicel, hidden from view, however, by the rounded base of the gall. Walls medium in thickness, possessing the rather soft texture of charcoal when dry; brown in color. This form is often found in enormous numbers on certain trees, bringing about early disintegration of the affected leaves. The lower leaves are more heavily infested due to the fact that the insects are apt to reach these first in their flight from the ground in the spring.