6 4 
BRITISH GALLS 
in shape and position; we may recall the bean-shaped galls 
caused by the hymenopteron Pontania pedunculi on Salix 
capvaea and S. cinerea. It is possible that Pevrisia ulmariae 
attacks the Dropwort, piercing the upper surface of the 
leaf, and that another species, indistinguishable to all 
appearances from it, attacks the Meadow Sweet, each 
insect keeping to its particular plant. Allusion has already 
been made to the highly interesting fact that ten species 
of gall-gnats which attack Salix humilis in America are 
practically indistinguishable the one from the other, though 
each causes a distinctive gall. It may be suggested, there- 
Fig. io— Spiraea Filipcndula galled by Pevrisia ulmariae. (i/i.) 
Fig. ii—Section of a Gall, showing Aperture on Upper 
Surface of the Leaf. (2/1.) 
Fig. 12— Spiraea ulmaria galled by Pevrisia ulmariae. (1/1.) 
Fig. 13—Section of a Gall, showing Aperture on the Lower 
Surface of the Leaf. (2/1.) 
fore, that Pevrisia ulmariae of the Dropwort deserves specific 
rank under the name of Pevrisia filipendulae. 
The Germander Speedwell has a hairy stem, and the 
under surface of the leaves is covered with short white 
hairs. The terminal leaves of this very familiar plant are 
commonly attacked by Pevrisia veronicae (Plate VIII., Fig. 2, 
magnified). The leaves become folded upwards and the 
hairs are abnormally developed, forming a gall which looks 
very like a bunch of white hairs (Plate VIII., Fig. 1). It 
