82 BRITISH OAK GALLS. 
about 3 mm. above its surroundings, by which time it 
will have altered to a brownish colour, and the texture 
hard and woody. 
The cap is concave within, and soon. after the gall 
reaches maturity it falls off, leaving the larval chamber 
with a very thin but hard convex septum upon it, and 
the upper margin of the thick cell walls exposed. The 
imago ultimately eats its way through the septum. 
The exposed margin is bordered by a thin rugged 
rim, within which is enclosed a circle of about twenty 
small punctures, with the hole of emergence in the 
centre. These little punctures “belong to an earlier 
period of growth; and through them. passed the 
vascular bundles that nourished the upper sappy half 
of the gall”’ (‘ Alternating Generations,’ p. 38). 
Miss E. A. Ormerod appears to have been the first 
to discover and record this gall in Britain, and also to 
figure a type specimen in two conditions of growth 
from a cluster found in 1877, in the neighbourhood of 
Isleworth. 
An oak stump in a coppice or a wood is one of the 
surest situations in which to find these galls, more 
especially if there be a number of small boughs 
growing from the stump. A careful scrutiny should 
also be made of trunks of old trees. When in clusters 
and exposed, as shown in the centre of Plate XIX, 
they are not difficult to find, but if a gall is solitary, 
and in the folds of a callus, as seen near the top of the 
same illustration, detection is less easy. After they 
have turned brown, or if surrounded by moss, they 
may very easily be overlooked, and on that account 
their distribution may be much wider than is generally 
known. 
Aphilothrix fecundatrix, Hartig. 
(Plates XX, XXI, XXII, div. B.) 
Cynips gemmex, Linn., Sclnck.; C. fecundatriz, Hartig, Marshall, 
Miller ; Aphilothri« gemmex, Mayr, Fitch; Aph. fecwndatriz, Adler, 
Licht.; Andricus fecundatriz, Mayr, Cameron; .A. gemmzv, Mosley. 
