146 THE OAK GALLS AND GALL INSECTS
sexual forms. The agamic forms also have hairs on the
antennae, and the ventral spine is thickly haired. There is no
sculpture on the mesothorax of the sexual generation. The
chief difference is in the ovipositor, which in the agamic forms
is long, slightly curved, and straight at the point, while the
sexual generation has the ovipositor short and somewhat hooked
at the end. This difference is due to the fact that in the former
case the eggs are laid in the bud, and in the latter they are laid
in the leaf. As pointed out by Dr. Adler, the study of the
ovipositors of the gall-making Cynipidae is very important, as
some forms, such as the sexual forms of the Dryophania group
and the corresponding forms of the genus Neuroterus, are almost
identical, except for the differences existing between the
ovipositors.
SYNOPSIS OF GALLS OF THE AGAMIC GENERATIONS
OF THE GENUS DRYOPHANIA.
In this genus, the galls giving rise to the agamic generation
are very similar in character, all being circular and found on the
veins at the back of the leaf.
1. (6) Hard and woody.
2. (5) Larval cavity small, walls thick.. .. .. D. longiventris
3. (4) Top depressed with an elongated elevation in the
centre of the depression .. .. D. disticha
4. (3) Top depressed with no elongated elevation in the
centre of the depression .. .. D. divisa
5. (2) Larval cavity large, walls thin .. .. D. agama
6. (1) Soft and spongy .. .. .. D. folii
I was unable to find any specimens of D. disticha in Epping
Forest.
(7). Agamic Generation. I. Dryophanta folii (Linn).
Inquilines. Synergus pallicornis (Htg.), S. tscheki (Mayr) and
S. vulgaris (Htg.)
Gall.
Appears on the under-surface of the leaf, arising from the
leaf vein with which it is connected by a small point. Two or
three may be found on one leaf. Colour: Green when young
becoming yellowish, the exposed side of the gall is often red.
Shape: Globular. This gall, which varies much in size and is