Dec. 1910.] BOTANICAL SOCIETY OF EDINBURGH 129 
hornbeam, Salix caprea, Solomon's seal. They also occur 
on the male fern, lady fern, and common bracken—that 
is, on about 113 species, mostly of herbaceous garden 
plants, and belonging to 44 natural orders. These were 
observed in the garden at Newton, near Dumfries (Kirk- 
cudbrightshire), and at various places in Duinfriesshire. 
This list is by no means the result of an exhaustive 
study of common British plants. I began by choosing 
plants at random, intending to obtain a percentage of 
British and cultivated forms which are regularly visited. 
But I have been so often deceived by not at first detecting 
the mites that I came to the conclusion that such a list 
would be misleading. 
It is very difficult to be sure that any plant is free from 
them. No one would ever suppose that almost glaucous 
rain-shy plants like Gypsophila and Thalictrum were in- 
habited by them. Nor are they absent from either glossy 
leaves or very hairy leaves, as some have supposed. 
It has been said by several authorities that acarodomatia 
only occur on dicotyledonous trees and shrubs. That is 
not; however, the case. They are very common on tall 
herbaceous plants, and even occur on quite lowly herbs, 
though this is unusual. 
True acarodomatia have been found on two species of 
Dioscorea in the Congo by de Wildemann (2), and Zimmer- 
mann (3) also speaks of mites on the under side of the 
leaves of Arundinaria japonica. That they occur on the 
common Solomon’s seal, where I found them abundantly 
at the base of the stem leaves, is a very interesting point. 
Another point that should perhaps be mentioned is that 
acarodomatia do not afford a clear proof of a warm, humid 
climate. Peola (4), in studying the fossil Tertiary flora of 
Piedmont, discovered well-marked acarodomatia on the 
leaves of Oreodaphne Heerii, Cinnamomum polymorphi- 
cum, and Lawrus canariensis; but it can hardly be said 
that this in itself shows that the climate was warm and 
humid. There are plenty of acarodomatia not only in 
Britain but in the tropics. 
It would be easy to give a list of those plants which 
have acarodomatia, but this is hardly necessary. The 
researches of Lundstrom, von Lagerheim (5), Malme (6), 
