The Scottish Naturalist. 303 



the twigs Y to V long, and J' to \' across, and tapering at both 

 ends. They resemble the other parts of the twigs exter- 

 nally ; internally they are woody and monothalamous — the 

 cavity being pretty large by the time the larva is full fed. 

 Each contains one hymenopterous larva. Found by Mr. 

 W. Vice in Sutherland in August, 1873, and by Dr. Buchanan 

 White in September, 1873, in Braemar. 

 Salix phyllicifolia L. — (a) Occur on the leaves beside the 

 midrib, projecting above, usually one on each side of the 

 midrib, in pairs. Each gall is about X long by J' broad and 

 deep on an average, but they vary a good deal. They do 

 not project at all below the leaf. They are monothalamous, 

 cavity being long and narrow, and the walls leather)'. Ex- 

 ternally they are naked and slightly wrinkled, and the 

 colour is dark green mixed with streaks of reddish-brown. 

 Each contains one saw-fly larva. Abundant in Glen Gairn, 

 &c, along with the next, (b) These are Pea-galls on the 

 lower surface of the leaves attached to the midrib and in- 

 cluding part of the lamina, being slightly visible on the 

 upper surface. They are slightly flattened, and somewhat 

 irregular — are J' to J' diameter. Surface naked, smooth or 

 slightly wrinkled, and bright green. Each contains one 

 saw-fly larva. Abundant in Glen Gairn, at Castleton, in 

 Glen Isla, at Lintrathen, &c. 

 Salix purpurea L.— -(a) Are Pea-galls attached to the mid- 

 ribs of the leaves below, but slightly visible above. They 

 are rather flattened, and are about J' diameter. They have 

 a large cavity in which lives a saw-fly larva. The surface 

 is naked and smooth, green or reddish in colour. Common 

 at Rubislaw near Aberdeen, and at Strachan near Banchory. 

 (b) Twig-galls. They occur on the younger (year old) 

 branches, and consist of swellings, which are sometimes 4 

 or 5 times the normal breadth, and \' to 2' long. The 

 woody substance of the twig remains unchanged, but the 

 pith is greatly swollen, and is hollowed out into cells 

 separated by partitions. The surface is green like the 

 twig, naked, and smooth or rough. Each gall contains 

 several larvae of Cecidomyia salicis Schranck, which species 

 of midge I reared in the end of May from galls gathered by 

 me in the beginning of May at Strachan near Banchory. I 

 am indebted to Mr. Roy for my first specimens of both 

 these galls. 



