The Scottish Naturalist. 193 



midrib. Each contains one saw-fly larva. They are com- 

 mon at the upper end of Glencallater, in Braemar. 



Salix viminalis L. — The galls are marginal, consisting of the 

 revolute edges of the leaf, which become fleshy and hard. 

 Externally they are yellowish, smooth, and shining. Each 

 separate gall is about ^-inch in length, not more than 

 T V-inch in breadth, but usually a number are placed end 

 to end. Each contained a larva of Cecidomyia marginem- 

 torquens (?) Very abundant on one stunted bush near Old 

 Aberdeen. 



Salix lapponum L., var. Stuartiana Sm., and var. armaria 

 Sm. — The galls in form and position resemble those on S. 

 nigricans ; but are light greenish-yellow, and downy. They, 

 like the last, occur in pairs. Each gall contains one hymen- 

 opterous larva. Common at the head of Glencallater. 



Salix arbuscula L. — The galls are in pairs, as in the last 

 two species, but they are rounder, and project more from 

 the leaf. The surface is smooth. Each contains one 

 hymenopterous larva. I have found these galls on one 

 plant on Little Craigandal, in Braemar. 



Quercus robur L. — (a) Galls occur on the chief veins of 

 the leaves on the lower surface. The shape is a flattened 

 sphere, ^inch to ^-inch in diameter. Colour light green 

 or reddish. Surface smooth. Structure woody ; walls 

 rather thin. Contain each one hymenopterous larva. 

 Usually several occur on a leaf, but they are not very com- 

 mon, (b) Artichoke gall, much resembling an artichoke 

 on a small scale. It seems to be a diseased development 

 of an acorn-cup, and contains a small diseased acorn, inside 

 which is one white larva. The gall is always sessile, 

 usually axillary, and single, but sometimes terminal, and 

 then in twos. Length about 1 inch, breadth about ^s-inch. 

 About Banchory abundant on one tree, scarce on others. 

 (c) On the blade or footstalk of the leaf ; if on the foot- 

 stalk, it remains attached when the leaves fall off. The 

 form is very irregular, projecting both above and below the 

 leaf; about the size of a pea. The surface is naked, 

 smooth, and yellowish-green above, like the leaf below. 

 Structure hard and woody, retaining its form when dried. 



