78 BRITISH OAK GALLS. 
thin, the interior is large, ellipsoidal in shape, about 5 
mm. in its vertical axis, and 2 mm. in the horizontal. 
The exterior has upon it longitudinal ridges, much 
more distinct and sharp-edged in some specimens than 
others, and entirely absent from some. Their colour is 
frequently pink and purple, but it fades when the gall 
is dry. They usually number from four to eight. I 
have found a specimen with ten. Their symmetrical 
arrangement can be seen best in a transverse section 
of a gall. 
Although the galls appear during several months 
they grow quickly and mature rapidly, and fall to the 
ground unless inhabited by inquilines. Those which 
vary from the normal shape in having short peduncles 
and are more obese, will remain attached to the twig 
for a long while. ‘The length they attain is remark- 
able. I have found dozens of varying sizes up to 22 
mm., many 25 mm., and one 29 mm. long. They 
usually project obliquely from the twig, and are 
slightly curved, sometimes standing erect on a hori- 
zontal branch and perfectly straight, sometimes at 
right angles on an upright twig, very rarely pointing 
downwards, and apparently never adpressed. 
Mayr describes this gall, from specimens found on 
Quercus pubescens, as “Scantily covered with mode- 
rately short, white, deflected hairs.” Pubescence does 
not appear when the galls are on other species of 
Quercus. 
These galls were first described by Malpighi in 
1682; and Giraud was the first to breed and describe 
the imago in 1859. EH. A. Fitch appears to have been 
the first to discover it in England, at Rayleigh in 
Essex, in 1874. I have found it local but plentiful in 
woods and coppices in various parts of the Hastings 
zoological district each season since 1899. 
The majority of the galls are occupied by the 
parasite or the inquilines. 
The imago does not emerge from some galls until 
the second spring after pupation. 
