128 BRITISH OAK GALLS. 
"Position of gall.-—Mostly in terminal, but also in axillary 
buds. 
Manner of growth.—Single, solitary, glabrous, vesiculate, 
ovoid. 
Colours.—Pale green, greenish-yellow, pale pink, light brown. 
Average dimensions of a mature specimen. — Height, 
8mm.; girth, 15 mm. 
May be sought during the months of April and May. 
Growth is complete by the end of May. 
The typical condition of the gall is unilocular and unilarval. 
The larva pupates in the gall. The imago emerges during 
May. 
Inquilines, Nos. 17, 72. 
Alternate agamic generation: ? Neuwroterus ostreus, Hartig. 
The dimensions of the largest gall of this species, of 
which I have a record, is—height 15 mm., girth 
21 mm. 
The proportion of axillary buds containing galls, 
as compared with terminal buds, is one in four. 
“There seems to be some doubt as to the agamic 
form of this species.” Beyerinck bred Neuroterus 
Aprilinus from galls of Andricus solitarius. Von 
Schlechtendal and F. Léew consider N. Schlechtendalt 
the agamic form. Mayr considers, “ that ostreus, 
being an Andricus, can hardly be the agamic of a 
Neuroterus” (‘ Brit. Phyto. Hymen.,’ vol. iv, p. 140). 
Adler is strongly of opinion that it is NV. ostreus, and 
his experience and experiments entitle him to be 
regarded as correct. 
Probably no other British oak gall equals this. 
species in the rapidity with which it develops, and 
reaches maturity. It is also one of the most obscure 
as regards its situation. The enfolding leaf-bud 
scales, and the very few days required for it to become 
mature and shrivel, combine to render its discovery a 
difficult matter, overcome mainly by experience.. 
Four or five days only, are necessary, from the time 
the gall expands sufficiently to increase the size of the 
bud, until growth ceases, and the imago escapes. 
