PHYTOLOGY. 



SCOTTISH GALLS. 



f Concluded from page 254. ) 

 By J. W. H. TRAILL, M. A. 



Salix fragilis L. ; S. alba L. — Galls of Nematus gallicola on 

 these willows are abundant in all places where I have col- 

 lected, even to Orkney. 

 Salix caprea L. — (a) Those described in Vol. I., p. 159, are 

 formed by Cecidomyia caprea Winnertz. They are about 

 the size of a large pin-head. They occur also in Perthshire, 

 Forfarshire, and Sutherlandshire. (c) This gall occurs on 

 the midribs of the leaves, and is most apparent below. It 

 consists of masses of galls clumped together, and originates 

 in a diseased development of midrib and veins, producing 

 hard woody swellings. Sometimes, though rarely, the galls 

 are separate from each other. Form and size of the masses 

 very variable, but the individual galls are from J' to J' across. 

 Externally, they are thinly covered with short hairs. Colour 

 — dark green above, yellowish green below. Hard and 

 woody ; monothalamous ; cavity, small ; larva escapes by a 

 small hole in the apex below. Abundant everywhere. 

 (d) Galls of Nematus pentandrce Retz. = N. medullarius H. 

 These consist of a swelling of the petiole (usually towards 

 its base), which becomes twice its proper thickness, and 

 forms an ovate body about J' diameter, and J-' long. Sur- 

 face, smooth, green, and shining. Structure, hard and 

 woody, enclosing a narrow crooked tunnel in the centre. I 

 am indebted to Mr. Cameron for the name of the species. 

 I found the galls common beside the Gairn and at Lin- 

 trathen. (e) On the leaves projecting from the upper 

 surface, and forming a small cone on the lower surface. 

 Size, J' to i' across. Form, irregular. Surface, naked, 

 wrinkled, deep red. Contains a small irregular central 

 cavity, nearly filled with refuse, etc., among which Phytopti 



