244 THE PLANTS OF THE GRAMPIANS. 
By reason of these local changes in relative position, it 
becomes difficult to determine the true places of many species, 
in a list where the names are intended to follow each other in 
accordance with the natural limits of the species. Not only 
would the series be varied in distant parts of the same island, 
but even in a list of plants for a space so circumscribed as the 
one now under notice, the relative position of the names will 
vary according to the situations in which the plants have 
been observed. Hence it will unavoidably happen, that the 
following series of names, where they succeed each other 
nearly in accordance with the absolute altitude of the lowest 
spots in which the plants have been observed, does not al- 
ways indicate the true position of the plants, one relatively 
to the others, in general climate. As a counterbalance to this 
unavoidable defect, I have occasionally added indications of 
other localities, beyond the tract of the Grampians, which 
tend to correct imperfect inferences respecting the climate of 
the plants, such as would be drawn if their ranges of height ` 
in the one tract were alone regarded. "Thus, looking to the 
heights given for Dryas octopetala, on the Grampians, it 
might be supposed more exclusively an alpine plant than 
Azalea procumbens or Salix herbacea; but when we also learn 
that it grows in abundance on moors about the sea-level, 1m 
Sutherland, and likewise at a moderate altitude in Yorkshire, 
we avoid the erroneous inference respecting the climate of 
this plant, which its very partial distribution on the Grampians 
might lead us to form. 
Here, as in the former paper, the names of the species 
correspond with those in the “ British Flora ;” and it has, 1n 
consequence, been deemed unnecessary to add the authority 
after each name. 
Lower Limits of Plants on the Grampians. 
Luzula arcuata. Seen only on the summit of Ben-na- 
muick-dhu, whose height I have estimated at 4,300 feet. 
(But since this plant is reported also to grow on Fonniven 
and Ben-More, in Sutherland, it must be found in that county 
