THE ENTOMOLOGIST. 



195 



Fi". ^>('> 



a moderately thin but hard wall, consisting of an outer layer, 

 originally green in colour, but afterwards brown, covering 

 the thin, brownish yellow, oviform inner gall. Most of the 

 galls have fallen by the beginning of November; but in the 

 following spring we often meet with leaves that have galls 

 at their basal half, and have been prevented from falling 

 by the thickening of the midrib. We have not been 

 successful in breeding the gall-maker as yet. However, I 

 have extracted a dead specimen from a gall. — -G. L. Map'. 



The description of this specimen — a female — is given in a 

 footnote. The gall is figured by both Malpighi and Reaumur. 

 It does not occur in Britain. From the galls of this species, 

 and from N. ostreus galls. Dr. Mayr bred a new Synergus, — 

 S. tristis, Mayr, — a species closely allied to S. nervosus and 

 S. Tscheki. It occurred in the spring of the second year, as 

 do also the other inquilines, — Synergus vulgaris. Hart., and 

 Ceroptres arator. Hart. — E. A. Fitch. 



50. Andricus curvator, Hart. {A.per- 

 foliatus, Schk., A. dimidialus, Schk., 

 G. axillaris, Hart.). — This very common 

 gall appears by the end of April, when 

 the leaves of Quercus sessiliflora, Q. pe- 

 dunculata, and rarely those of Q,. pubes- 

 cens, begin to develop themselves. It 

 appears on both sides of the leaf, often 

 causing it to curl up, and looks like a 

 green spherical swelling, of about the 

 size of a pea. It often occurs at the 

 margin of the leaf, when we find on 

 the outer or exposed side a more or 

 less distinct furrow, extending in a 

 curve from the centre of the lower side 

 to that of the upper side. This furrow A. curvatoe (& in section). 

 is absent in those galls which grow in 



the middle of the leaf, and are surrounded by the parenchyma 

 (A. perfoliatus). This gall is bare above, and covered with 

 fine, short, sparse hairs below ; only when on Q. pubescens 

 is the gall piliferous on both sides. It is somewhat cartila- 

 ginous, and has a moderately thin wall enclosing a large 

 cavity, to the sides of which the small, brown, thin-walled inner 

 gall, which is scarcely the size of hcmp-sccd, loosely adheres. 



