Cecidomyia (tiliae) verrucicola, n. sp. Wart-shaped, round, pale green galls, 3 — 4 millim. in diameter, projecting on the upper and underside of the leaves of the linden. They occur between the ribs and veins and often upon them. In autumn they become brown, hard and woody, and spring open on the underside, a circular piece detaching itself and either falling to the ground, or remaining fastened to the gall by a small portion of its circumference, in the shape of a lid. Inside of the gall, when green, there is a low-roofed cavity, containing a white larva, with a distinct breast bone, heart-shaped anteriorly, and ending in an elongate point posteriorly. The dry galls are empty. I found them common on Goat Island (Niagara Falls), on the hills near West Point, N. Y., in Cambridge, Mass., etc., in August and September, on the young shrubs of the linden.