78 EIUTISH OAK GALL.S. 



thin, the interior is large, elHpsoidal 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, l)ut 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 Ijranch 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 

 Qaercus imhescens, 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 

 1082; and Giraud was the first to l^reed and describe 

 the imago in 1859. E. 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. 



