1. Gall on nut. Caryomyia nucicola. (3) 1. Gall on leaf. 2. 2. An apparent elongate enlargement of vein. Cecidomyia cynipsea (?) (4). 2. An inrolled leaf edge. (2). 2. Galls arising from intervenal tissue between veins or immediately adjoining veins; radially symmetric structures with principal axis more or less perpendicular to leaf blade. 3. 3. Galls double-chambered as seen in vertical median section. 4. 3. Galls single chambered. 7. 4. Galls definitely depressed. (5). 4. Galls small, sub-globular. (6). 4. Galls definitely conic. 5. 5. Elongate gall with rounded base in definite visible socket. (7). 5. Shorter gall attached by pedicel from rounded base not articulating with definite socket. 6. 6. Proximal chamber of gall, conic. (5). 6. Proximal chamber of gall, depressed. (8). 7. Galls definitely conic; forms having rounded bases, the distal portion is sufficiently drawn out to place the cecidium under this class. 8. 7. Galls spheric, sub-spheric or depressed. 15. 7. Galls sub-cylindric, 2½-3 times as long as wide. 22. 7. Galls obconic, i. e., part projecting from leaf is flat topped, constricted proximally to the pedicel embedded in the leaf. 25. 7. Blister gall, intercalated in the leaflet, projecting on both sides. Cecidomyia? sp. (33). 8. Small irregular, low, masses of tissue always in axils of principal veins of leaflet. Eriophyes sp. (1). 8. Galls definite structures projecting prominently from leaf surface. 9. 9. Conic gall generally with strongly recurved tip appearing as though lying on side, decumbent. (9). 9. Galls erect or tilted, seldom bent over, however, beyond angle of 45. 10. 10. Gall with flattened sides, pyramid-like. (10). 10. Galls with sides flattened. 11. 11. Proximal half of gall conic, never sub-globular. (11). 11. Proximal half sub-globular. 12. 12. Galls smooth. 13. 12. Galls pubescent. 14. 13. Galls large, 4-7 mm. long. (12). 13. Galls small, 1½-4 mm. long. (13). 14. Trichomes very long coarse. (14). 14. Pubescence short, fine. (15.) 15. Galls attached by proximal pedicel embedded in leaf, as seen in a median vertical section. 15. Galls attached by structure extending from leaf into base of gall, which remains on leaf when gall falls. 20. 16. Walls thick, soft. 17. 16. Walls thin, 18. 17. Galls smooth, depressed or with upward flaring walls forming a saucer or cup-shaped structure distal to the chamber. (16). 17. Gall globular, finely pubescent like that of a peach. (17). 18. Surface perfectly smooth, symmetrically sub-spherical galls. 19. 18. Surface minutely shagreen-roughened, gall asymmetric, one side prominently extended laterally. (18). 19. Small galls, 2½ mm. dia., nipple expanded and flattened resembling the end of a bottle. (19). 19. Larger gall, 3-4 mm. dia., nipple short, pointed. (20). 20.