16 BRITISH OAK GALLS. 
(£) Red.—The same chromatic gradations are found 
in this colour, from the most delicate suffusion of 
pink, as in 7’. crustalis, until a deep crimson or rose- 
madder is reached, as shown in A. Sieboldi. The most 
charming example of a median red tint is that of D. 
scutellaris when at the zenith of its glory. Teras 
terminalis also often exhibits a wealth of beautiful 
tints. The brilliant red spots or stripes on the green 
ground of S. baccarum accentuate its resemblance to a 
red-currant berry. The red stripes on Dryophanta 
longiventris are worthy of remark. The pretty pink 
and light red of D. divisa deserves notice ; it is, how- 
ever, transitory—the brown soon asserts itself. The 
crimson’ margin of many specimens of Neuroterus 
leviusculus provides a charming contrast to the 
greenish-yellow centre. The red and crimson stellate 
hairlets of N. fumipennis and N. lenticularis clothe 
these galls with rare and most beautiful effect. In 
addition to these distinctive colours all tints of yellow, 
also orange, both pale and deep, are to be seen in many 
galls. White is somewhat unusual, Andricus noduli 
giving the best example. Aphilothrix Sieboldi is often 
cream coloured when shielded from the light by loose 
earth or dead leaves. 
MoprricaTions IN DEVELOPMENT. 
(a) Due to external inflwences.—This division in the 
study of oak galls should receive the attention of the 
collector and the student, because from the examination 
of affected specimens some very interesting facts can 
be deduced, and much of the economy of gall-producing 
agents and their allies understood. It is a section 
which is very near that of “ Dissimilarity of shape due 
to aberrations,’ yet sufficiently distinctive to be 
separated. 
Of the modifications in shape and size caused 
by— 
eh Overerowding not much need be said. The 
