212 Professor Trail on the [sess. lii. 



3. Bushes of this willow near Christiania also bore very 

 numerous examples of the galls named Cephaloncon umhrinum, 

 Biemi (the work of PJujtoptiis sp.), scattered irregularly over 

 the upper surface of the leaves. They are dull reddish or 

 brown " nail-galls," irregularly rounded in form, attached by 

 a narrow neck to the leaf. Each opens on the lower surface 

 of the leaf, but the opening is nearly closed by a dense tuft 

 of grey woolly hairs. The galls vary from 1 to 2 mm. in 

 diameter. 1 have these galls from Aberdeenshu-e, and they 

 are recorded from Vienna. 



S. "l pliyJicifolia (Linn.), Sm. — I have what seems to be a 

 branch of this species of willow from the Simodal, in Hard- 

 anger, bearing on the leaves several galls, which agree very 

 closely in their structure with those of Nematus ischnoccrus, 

 Thorns. They are almost always in pairs, one on each side 

 of the midrib. They are about 12 mm. long by 4 mm. 

 broad, with the sides parallel and the ends rounded ; they 

 do not project at all below the leaf, but are prominent above. 

 The upper surface is dark green or purplish red, and the 

 lower surface resembles that of the leaf. Each gall is 

 tenanted by the larva of a sawfly, probably N. ischnoccrus, 

 Thomson. I have found galls that I cannot distinguish 

 from this in Braemar, Aberdeenshire, on S. phylicifolia, S. 

 nigricans, and >S'. arbusculci, and on S. Icqypoiium. In the 

 same locality were galls similar in form, but of rather 

 smaller size. Mr Cameron {Brit. Hymcnopt., ii. pp. 196- 

 197) says that the only localities he knows for N. ischnoccrus 

 in Britain are Braemar, Eannoch, and New Galloway ; and 

 he names as its food-plants >S'. purpurea and S. laurina. It 

 was first recorded from Sweden. 



S. nigricans, Sm. — On this willow near Vik, and in the 

 Simodal, last August, I found a profusion of galls on the 

 leaves, in the form of gl(il)uliir l)odies about the size of 

 peas, attached to the lower surface of the leaves, and 

 scarcely showing at all on the upper surface. They are 

 smooth, shining, and yellowish green, sometimes with red 

 patches where exposed to the sunshine. The central cavity 

 in each is at first rather small, but is rapidly enlarged as the 

 sawfly larva within eats away the substance of the walls; 

 and when the larva is full fed the gall is little more than a 

 shell. These galls are so entirely similar to those of N. 



