The Scottish Naturalist. 253 



When mature they fall off, leaving holes in the leaf. Usually 

 there are several on a leaf, (b) In 1873 Dr. Buchanan White 

 sent me galls which had been sent him by Sir T. Moncreiffe, 

 from Perthshire, in June. Theyareformed by Aulax Glechomce. 

 The galls are usually situated on the midrib of a leaf, but some 

 times on a side vein or on the petiole, and project chiefly below. 

 They are sometimes separate, sometimes two or more grow 

 together. When separate they are spherical, }i' — j£' diame- 

 ter, but when united they form masses sometimes about one 

 inch across. The surface is reddish-brown or green, and is 

 covered with short whitish hairs. When distinct, each gall is 

 monothalamous, and has very thick fleshy walls, there being a 

 compact inner cell, closely surrounded by a fleshy outer wall. 

 Polygonum Persicaria L. — On this plant there occurs galled 

 leaf margins, consisting of an involute margin, which 

 becomes thick, hard, fleshy, and red or yellowish, and con- 

 tains one or more larvae of Cecidomyia persicaria L. 

 Usually several leaves on a plant affected. Found by Dr. 

 Buchanan White near Dunkeld, in September, 1872. 

 Polygonum amphibium, L. — Similar galls were found by me 



on this plant near Dunkeld, in September, 1872. 

 Polygonum viviparum L. — In June, 1873, Dr. Buchanan White 

 found galls in Braemar, which resembled the above in every- 

 way except in being of smaller size. One of the leaves 

 sent me by him contained a small white compactly-spun 

 cocoon. 

 Populus tremula L. — (a) Galls of Cecidomyia treviulcz Win- 

 nertz, occur usually on the twigs or petioles, sometimes even 

 encroaching on the lamina. They are irregularly rounded, 

 the size of a small pea, smooth externally, and vary in 

 colour, those on the petiole being reddish or yellowish, 

 those on the twigs resembling the bark in colour. Internally 

 they are hard and woody ; the central cavity is small. 

 The larvae emerge from the galls in the end of July or the 

 beginning of August, and the galls then dry and become 

 brown, but retain their form. Common in Glen Gairn and 

 Braemar. I have found on the leaves themselves, near 

 Ballater and near Balmoral, in August, 1873, galls which 

 may belong to the same species, but which differ from those 

 just described in being lenticular, only y&' diameter and i' 

 deep; besides which I have never found them in the same 

 locality. Usually also a number of galls of this latter kind 



