fested galls are usually more or less globular, in groups, but not so completely fused into a single mass as normally. Internally these galls are only loosely woody, with several small larval chambers (without a distinct larval cell-wall) arranged somewhat radially and near the bark. Each portion of the fused mass of the normal gall is woody and will contain toward the center one to three good-sized larval cells with a distinct cell-wall. This is a typical instance of the change effected in the structure of a gall when it becomes inhabited by inquilines. A few other similar instances are well known; it is likely that many others will come to light. A careful study of these might indicate some of the factors which act to produce galls. In A. punctatus the "inquiline" seems to be more truly a parasite, for usually gall-wasps are not reared from galls which breed out the Synergus, nor is the gall-maker's larval cell found to be developed to any size. It is likely that the Synergus does not attack the Andricus larva directly, but indirectly by robbing it of the food in the gall.
Aulacidea abdita, new species
Plate XXI, Figures 6 and 7
Male.—Similar to the female, but differing as follows: antennæ 14-jointed, third joint curved (but only slightly so), whole antenna reddish yellow, the same color as the legs; median groove less distinct and shorter; abdomen much shorter than in the female, rufous to piceous, and quite dark on the posterior half; wing-veins lighter brown than in the female, the areolet large or very large and elongate on the cubitus toward the basal vein; length, 1.2–1.7 mm.
Galls.—None. The insect lives in cavities (Figs. 6 and 7) in the pith of the stems of Lactuca elongata and most likely of other species of Lactuca. There is no