1887-88.] Professor Trail on the Galls of Norway. 201 



The Galls of Nonoay. By James W. H. Trail, M.A., M.D., 

 F.L.S., Professor of Botany, University of Aberdeen. 



(Read 8th JIarch 1888.) 



During two visits which I made to Norway — the first in 

 1878, to the fiords near Bergen, Trondhjem, and Christiania, 

 and the second, in August 1887, to the upper part of Hard- 

 anger with the Scottish Alpine Botanical Club, — I collected 

 such galls as I could discover, chiefly with a view of com- 

 paring them with the species that I had found in Scotland. 

 On working them out I found a great general similarity to 

 the Scotch species, though with minor differences ; but I was 

 still more interested to find that very little had been pub- 

 lished that threw light upon the galls of Norway, and that 

 my observations seemed to add considerably to previous 

 records, slight though my collections were. In the hope 

 that they may prove of some value as a contribution towards 

 a knowledge of the geographical distribution of European 

 galls, though no actual novelties have to be put on record, I 

 have prepared an exhaustive account of the galls brought 

 home by me, restricting the descriptions to those characters 

 of diagnostic value. Por each I have given the localities in 

 which the specimens were found by me in Norway, the 

 localities in Scotland, when Scotch, and the recorded distri- 

 bution on the Continent of Europe. 



Por the sake of easy reference, the galls are arranged 

 primarily in the order of the plants on which they occur 

 (following the arrangement in use in English books) ; and 

 where several galls w^ere found on any host, e.g., on Tilia 

 parvifolia, they ai'e arranged in the order of the relative rank 

 of the gall-makers, beginning with the higher insects, and 

 passing downwards to the mites. A list is added, in which 

 the gall-makers are arranged in their relative rank, without 

 reference to the host-plants. 



In an Appendix a summary is given of all the information 

 that I have been able to gain with reference to any previous 

 records of galls or gall-makers in Norway. 



Cerastium triviale, Link. — Pseudo-galls of an homopterous 

 insect, Trioza Cerastii, H. Loew, were of very frequent occur- 

 rence at Vik, Eide, and other places in Hardanger, in August 

 1887. They are produced by the irritation due to the con- 



