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 averaging 2.0 mm. in diameter, hard but thin-walled, entirely free, rolling about within the gall. Singly or in clusters, sometimes somewhat fused together, on the young buds, aments, petioles, and leaf-blades of oaks, sometimes only slightly attached, at other times inseparable from the leaf-tissue. On Quercus coccinea, Q. falcata, Q. ilicifolia, Q. imbricaria, Q. marilandica, Q. palustris, Q. phellos, Q. rubra, Q. velutina, and most likely other red oaks.

.—Cotype females, males, and galls in the collection of the Museum of Comparative Zoology.

I have examined the types of Andricus notha (Osten Sacken) and the adults appear to be true palustris. The galls are somewhat more oval in shape, with the larval cell more elongate, but I have found that that character shows gradations in large series of palustris and there is little doubt that notha is, as Osten Sacken strongly suspicioned, not distinct. Beutenmüller makes Andricus pusulatoides Bassett a synonym of notha. Beutenmüller (1911, Bull. Amer. Mus. Nat. Hist., XXX) also says that he cannot find essential differences between true palustris and the types of Dryophanta aquaticæ, D. laurifoliæ, and D. liberæcellulæ but, because of lack of sufficient material, he prefers to consider them distinct. I can hardly see any justification for keeping those names out of the synonymy.

The gall of Andricus palustris palustris is one of the best-known of the galls of early spring, appearing abundantly on red oaks of many species, often before any leaves have appeared. They often crowd closely on the flowers of the oaks. When the galls first appear they are solid, with the larval cell distinct but entirely connected with the outer walls of the gall; but within a very few days or even hours the gall, growing very rapidly, becomes hollow, leaving the larval cell (which had gained its full size in the young gall) loose to roll about within the enlarged outer wall at every movement of the branches of the tree. How the nourishment is provided for the larval cell and the enclosed larva is a process yet to be studied. During damp weather the galls will be found to contain a more or less viscous liquid, and placed in a pan of water they become filled with this liquid. It is probable that food is carried by osmosis to the larval chamber. Galls taken from the tree will grow still larger if placed directly on very moist sand or in water, indicating how independent an organism these deformations may become.

Because the galls are so very succulent they should not be gathered for breeding until they are about mature, and should then be placed directly on very moist sand. The growth of these galls is very rapid after their first appearance upon the trees and they are mature within