begins, makes this plan also unsuitable. We maj^y 
however, adopt a modification of it in combination 
with the next method, which is not only a scientific 
one, but easily followed out on paper and on the 
ground. 
This plan (which was submitted to and a,dopted by 
the Society in 1869) is to divide by the watersheds of 
the principal rivers. In this manner we obtain 
natural divisions of Perthshire, and by ascertaining 
the Fauna and Flora of each district, we will be able 
to obtain accurate information as to the distribution 
of species throughout the county. 
To each division has been given an appropriate 
name, the initial letter of which can be used for the 
sake of brevity and convenience. 
The districts are as follows :— 
1. Forth (F.), including all parts drained by the 
Forth and its tributaries. 
2. Lomond (L.), a small district draining into Loch- 
Lomond. 
3. Earn (E.), diained by the Earn and its tributaries. 
4. Perth (P.), drained by the Almond and Braan, 
and by the tributaries on the west side of the 
Tay between these two rivers. 
5. Breadalbane (B.), drained by Loch-Tay and its 
influents, by the Lyon and the Tay as far as the 
mouth of the Tummel. 
6. Rannoch (R.), drained by Loch Rannoch and its 
influents, by the Tummel, by Loch Garry, and 
by the west side of the river Garry. 
7. Athole (A.), including all parts of the county east 
of the Tay, Tummel, and Garry, and north of 
the Isla. 
8. Gowrie (G.), all parts east of the Tay and south 
of the Isla. 
These, then, are the divisions by the watersheds. 
Let us now see how they are situated as regards the 
first-mentioned mode of natural division into Littoral, 
Lowland, Subalpine, and Alpine districts. 
“ Littoral” includes the parts immediately adjoin¬ 
ing the sea, or the tidal portion of rivers influenced 
by the tide, and only a few feet in elevation above 
the sea level.. 
