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 others are agglomerate but essentially monothalamous; the galls of four of the species (the galls which are separable from the plant), A. glechomæ, A. kernei, A. pisum, and A. latreillei, are distinctly monothalamous. No species of Aulacidea produces a gall which is monothalamous, or separable, or which develops distinct larval cells. The galls of Aylax are very evidently less primitive, though not all of the galls of this genus are as complex as others.

Reproduction in this group is most likely normal, sexual reproduction. The males of most of the species (not including A. glechomæ) are known, and the sexes are about equally well represented in collections, but I have not had an opportunity to breed large enough numbers of any of the species of the genus to obtain reliable data as to the ratio in which the sexes exist. A. glechomæ may regularly reproduce agamically.

There is no alternation of generations in Aylax glechomæ and Aylax papaberis (=A. rhæadis Bouche), as Adler proved (1881) by experimental breeding of the insects for successive generations. Nothing of the observations made on species of the genus concerning emergence dates, etc., would seem to indicate any likelihood of heterogeny occurring anywhere in the group.

In summary, species of Aylax are primitive in abdominal characters choice of host plant, degree of complexity of the galls of several species, and in manner of reproduction. The genus, however, evidently incluides more specialized forms than Aulacidea, as evidenced by the specialized wing-venation, the enlarged second segment of the abdomen of some of the species, the more complex character of the galls of most of the species, and in the possible existence of agamic reproduction in one species. Aylax glechomæ is in many respects the most specialized of the species of Aylax. But in no cases do the species show as specialized characteristics as those of most of the oak gall-producing Cynipidæ.

I believe Aylax was derived directly from Aulacidea.

The radial cell in thirteen of the fourteen known species of this genus is open, indicating some degree of specialization, but the occurrence of the closed cell in one species, D. fragariæ, indicates that the group is descended directly from some closed-cell genus such as Aulacidea.

The first abscissa of the radius for most of the species is slightly angulate, but in a few species, e. g., Diastrophus rubi, it is still arcuate, the primitive condition. Evidently, there has occurred some evolution