have been made heretofore. These galls, however, differ only in details of size, color, and their degree of hardness and there can be no objection on these grounds to considering the two as varieties of a single species. In first describing the form pubescentis Mayr (1881) suggested that (translating): “D. pubescentis … should perhaps be considered only a subspecies of D. folii”—a suggestion which, if it had been followed, would have given us a better understanding of the common ancestry of the two and of the geographic isolation which must be chiefly responsible for their preservation as genetic entitites.
The variety folii occurs on Q. pedunculata and Q. sessiliflora thruout most of its range. In its more southern extension it undoubtedly occurs on Q. pubescens (acc. Straton 1894 and Connold 1902 in England, Houard 1914, Marcellia 13, in Central France, and particularly acc. Cotte 1910 in Provence). Further collections made in areas where both folii and flosculi occur on Q. pubescens should be studied to ascertain how much interbreeding may go on where the two enjoy neither host nor geographic isolation.
As far as our records go, the variety folii reaches the Mediterranean coast only in Provence, unless Gräffe's record (1905) for Triest proves correct. There are no substantiated records for folii south of the Pyrennes or the Alps. Flosculi on the other hand does not get north of these mountain ranges, altho it does occur in a restricted Mediterranean strip in Provence, and farther east it extends thru Austria and Bohemia as far as the boundaries of German Silesia. It is notable that insects of folii and flosculi in my collection are all readily separated by the characters given above except for the material which comes from Moravia, Bohemia, and southern Silesia. Among nearly four hundred insects of folii which I have from localities in Denmark, France, and Central Germany, not a single one shows appreciable variation toward pubescentis. But out of 21 adults from Moravia (Baudys coll.), one shows the radial vein and another the scutellum typical of flosculi. One of my three insects from Dresden (southern Silesia) has a distinctly bent tip to the radial vein. All of the Moravian material is unusually dark in color. A Mayr specimen (determined as scutellaris) from Vienna also tends toward flosculi in its wing venation.
