1887-88.] Galls of Norway. 211 



from the leaves, carrying a portion of the tissue with them, 

 so that the situation of each is then marked by a round hole 

 through the leaf. I have this gall from Perthshire, and have 

 seen it common in England. It has been recorded from 

 France, Germany, and Austria. 



Populus tremula, Linn. — I have a leaf of this tree, picked 

 near Christiania in 1878, which bears the gall known as 

 Heliazeus Populi, Kirchner, the work of a mite {Phytopus sp.). 

 It is always situated on the base of the upper surface of the 

 lamina, just where the petiole joins it, and is probably a dis- 

 tortion of the leaf-glands that normally occupy this situation. 

 The galls are rounded warty outgrowths, 1 to 2 mm. high by 

 1 to 3 mm. broad, and are usually red or yellow. They are 

 rather common in the north-east of Scotland, and I have 

 thus been able to examine the development in fresh speci- 

 mens. When full grown they are of firm texture, and in- 

 close small irregular cavities, tenanted by the mites. At first 

 each consists of two swellings (the glands), one on each side 

 of the midrib, which are soft and fleshy. These soon overlap, 

 until at last the two look like a single gall. The galls have 

 been recorded from numerous localities in Germany and 

 Austria. 



Salix Caprca, Linn. — 1. I have examples, gathered near 

 Christiania, of galled petioles, swollen for the greater part of 

 their length to more than twice the natural thickness, but 

 otherwise little changed externally. On section each is found 

 to enclose a cavity occupied by a larva of a sawfly, probably 

 Euura venusta, Zaddach. I have found similar galls in Glen 

 Gairn, in Aberdeenshire ; and Mr Cameron records them 

 from near Glasgow. P, venusta was described from German 

 examples. 



2. Galls of a midge (Cec. Caprece, Winn.) were gathered by 

 me in 1878 near Christiania, and in 1887, at Odde, in Har- 

 danger. They are about the size of small shot, and are 

 woody in texture, rovmded, but rather more conical below 

 (where there is a small hole formed when the gall is mature), 

 and yellowish in colour. They are scattered irregularly over 

 the leaf, the conical part below, and the rounded part above 

 the general surface. Each is occupied by a single larva. 

 These galls are plentiful in Scotland, and they have also been 

 recorded from France, Germany, and Austria. 



