1887-88.] Galls of Norway. 213 



Salicis-cinerece, Ketz., on various species of smooth-leaved 

 willow, and that sawfly is so widespread, that the galls from 

 Hardanger probably belong to this species. 



Betula alba, Linn. — 1. Erincuni letulinum, Schum., was 

 common on the lower surfaces of the leaves near Trondhjem 

 and Christiania in 1878, and near Eide in 1887. This 

 Urineum sometimes forms small spots along the midrib and 

 the larger veins, sometimes isolated patches of densely 

 crowded hairs scattered on the lower (rarely the upper) sur- 

 face of the leaf, and sometimes it occupies almost the whole 

 of the surface. The hairs are at first nearly white, but 

 become rusty brown. The mites live between them. U. 

 hetulinum is very common in Scotland, and is recorded from 

 France, Germany, and Austria. 



2. In the same localities as the last-mentioned gall I also 

 found another gall formed by a species of Phytoptus, but of 

 markedly distinct structure. The latter galls resemble hard 

 little warts in the tissue of the leaves, as many as hfty 

 or sixty occasionally existing in a single leaf, but they 

 very seldom coalesce. Though scarcely reaching 1 mm. in 

 diameter, they project on both surfaces of the leaf- blade, 

 especially in the dried leaves, as their hard texture prevents 

 shrinkage. Each surrounds a relatively large cavity, which 

 opens by a narrow outlet below, protected by a small tuft of 

 hairs. The mites live in the cavity of the gall. I have 

 found the galls very frequently in Scotland ; they occur also 

 in England, and have been recorded from many places in 

 Germany and Austria. 



Alnus incana (Linn.), D.C. — This alder in Hardanger seems 

 to take the place filled by A. glutinosa in Scotland. I have 

 found on it two kinds of mite-galls {Phytoptus sps.). 



1. Erineum alnigenum, Lk., described by Link as a fungus 

 under the name Phyllerium alnigenum, was of frequent occur- 

 rence near Christiania, and near Eide in Hardanger. It is 

 far more frequent on the lower than on the upper surface of 

 the leaf, and assumes the form either of well-defined spots 

 of hairs, or patches diffused irregularly along the midrib 

 and larger veins. At first the hairs are pale, but the spot 

 becomes rusty brown, approaching a russet brown, surrounded 

 by a narrow pale border. The hairs .are slender, bent, and 

 blunt. This gall has been recorded from Saxony, from the 



TRANS. BOX. SOC. VOL. XVII. P 



