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Holcaspis Mayr (not of Chaudoir) is a synonym of Disholcaspis Dalla Torre and Kieffer.

In this genus the radial cell is open. In most cases the apical portion of the subcosta is very short or lacking and the radius terminates a considerable distance from the mnargin of the wing. This is the greatest reduction, the greatest specialization, of these veins, found regularly in any genus in the family.

The first abscissa of the radius in every instance is very angulate, the angle approaching ninetv degrees, and the projection into the radial cell is always very distinct. This comes very near to being an extreme of the form assumed by this vein in the Cynipidæ—the extreme which we have considered the most highly specialized condition.

The second abdominal segment is not as highly developed as in many of the other oak gall-makers, though it is more developed than in the Aulacini. It regularly covers a half of the abdomen. These considerations, taken alone, would suggest that Disholcaspis is either more primitive than the rest of the Cynipini or that it has developed independently of most of those oak gall-makers.

The hosts of these insects is Quercus, these wasps showing the same extreme specialization in this choice of hosts as is characteristic of all of the Cynipini. Another sort of specialization shown by this group is the production of the galls of most of the species upon a single part of the plant-the lateral buds. It appears to be the stem that is affected, but M. T. Cook ( 904, p. 143) pointed out that for at least some of the species it is really the bud that produces the gall. Most of the genera of gall-wasps include species which will attack the several parts of the plant, but in Amphibolips, Cynips (of European authors), and Disholcaspis the species of each genus are confined mainly to a single part of the plant. This seems to be specialization that, following generic lines, indicates something of the phylogenetic position of the group.

The galls produced by the species of Disholcaspis are among the most complex productions of the Cynipidæ. The galls are all monothalamous; they show a distinct separation of the zones resulting especially in the formation of the very distinct, highly modified wall of the larval cell, which in most species is entirely free in the central cavity of the gall; and the galls are only very slightly connected with the plant, in many cases leaving the host long before the insect has reached maturity. These are all characters indicating a high degree of specialization. In some cases the galls assume peculiar forms (e. g., Disholcaspis