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186 data as the galls, it is quite certain that no one would arrive at our present classification, and the accompanying host and distributional data would then be largely meaningless. How much insect taxonomy is inadequate and misleading is a matter for serious contemplation.

That the differences in these agamic galls are not due to the qualities of the various oaks on which they occur, is proved by the occurrence of three types of galls, the work of three different varieties of echinus, on Quercus dumosa in Southern California.

Attention should be drawn to the peculiar, crystalline materials of which all these agamic galls are built. Between the thin epidermis and the wall of the larval cell there are solid masses of microscopic, deformed crystals intermingled with a few fibers of similar material. This substance is commonly reputed to be gallic acid (as in Fullaway 1911), and if this is so, these galls must have a very high percentage of the material. It would be interesting to know how the gall in its development segregates or stimulates the manufacture of this substance in the normal oak leaf. When the galls are moist (whether young or old) they are as soft as rubber. When dried, they quickly become as hard to cut with a knife or drill as tho they were made of so much compacted, ground glass. In order to mount such specimens on insect pins for preservation in our collections we soak the galls in water for a few hours, or place them out-of-doors in a damp location for a few days, after which they are readily penetrated by the pins.

In addition to the six varieties now known in this species, there are probably two or three additional varieties still to be described from California, but probably none to be expected elsewhere in this country.

Figures 23, 154-159, 175

Holcaspis douglasii Ashmead, 1896, Proc. U.S. Nat. Mus. 19:127. Cockerell, 1900, Ent. Stud. 1:9. Thompson, 1915, Amer. Ins. Galls: 10, 39.

Dryophanta Douglasi Mayr, 1902, Verh. zoo.-bot. Ges. Wien 52:290.

Holcaspis Douglasi Dalla Torre and Kieffer, 1902, Gen. Ins. Hymen. Cynip.: 53.