74 
about ;4;-} inch diameter; afterwards they project in a low cone 
on both surfaces, and enclose a pretty large cell, as the walls are 
very thin. When mature they are readily detected, being much 
paler than the rest of the leaf ; but before maturity they are green, 
and very difficult to find, the readiest eye-mark being the radii, 
which pass from a small knob in the centre to the circumference ; 
the radii are less regular on the lower surface; both surfaces are 
naked. These galls are not uncommon on oaks beside the Dee, 
_ at Banchory ; the insects emerge in the beginning of July. 
Andricus quadrilineatus, Hart. For the description of this species, see O, 
under ‘ Catkin-galls’. They sometimes occur on the midribs of 
the leaves, in which case there is generally a gap in the lamina 
opposite the gall. The form on the leaves has been described by 
Schlectendal as a distinct species, under the name of Cynips 
marginalis. 
Sub-div., Galls on the Male Catkins. 
Spathogaster baccarum L. Vide t, under ‘ Leaf-galls’. 
M. Galls of Andricus ramuli L. (= Teras wmentorum, Hart), They 
are generally called ‘cotton galls,’ on account of their great re- 
semblance to a ball of white cotton 3-1 inch in diameter. Each 
ball is made up of a multitude of small, hard, woody galls, about 
the size of whin seed, which are covered with long, flat, dry, 
twisted hairs, like cotton fibres. Sometimes galls occur singly 
on the catkins. They appear in the end of May and in June; the 
insects emerge in July. They are common at Banchory, and near 
Ballater. 
N. Galls of Andricus amenti Gir. They originate from the anthers, 
are ovate, acute, sessile, about y4 — vz X vr inch, marked witha 
slight furrow down the middle on each side, indicating the con- 
nective. The surface is brown, and is covered with very short, 
stiff hairs; the walls are very thin. Several galls usually occur on 
each catkin. They occurred to Dr. Vice and myself rather com- 
monly at Ballater in June. 
0. Galls of Andricus quadrilineatus Hartig. There are usually four or 
five of these galls on each catkin (sometimes they occur on ‘the 
midrib of the leaf); and they are oval, about § x #¢ inch, and 
when fresh are naked, green, and smooth, or very faintly striated ; 
on section, a woody inner gall (rather large-celled) is found to be 
closely surrounded by and united to a green, fleshy outer layer. 
On drying, the outer layer shrivels up, and striz appear forming 
a net-work, the variations of which, in depth and regularity, have 
been considered to warrant the conclusion that they belong to 
distinct species. They occur, in June, at Muchalls, near Aberdeen, 
at Banchory, and at Ballater, and will probably be found else- 
where when sought for. 
Div. 2. Galls of Cecidomyide. 
p. These galls are simply portions of the margins (especially the 
tip of the segments) which become folded against the back of the 
leaf, thickened, fleshy, and yellowish-green ; they are hardly seen 
at all from the upper surface. Usually several are found on a 
leaf. Each cavity so formed is tenanted by one or more whitish 
or orange larvee of Cecidomyia (Diplosis) dryobia Fr. Low. They 
are common in many localities on Deeside, and elsewhere, in June 
and July. 
Fagus sylvatica L, (— Beech). Galls of Cecidomyia (Hormomyia) piligera 
