18 THE SCOTTISH NATURALIST 
more incomplete and broken, and where such plants as 
Nardus stricta, Deschampsia cespitosa, Eriophorum, etc., take 
a prominent place, we find a richer fauna, richer, that is to 
say, in population-density, than that of the drier moor. They 
form, in my experience, the metropolis of the Golden-plover, 
Curlew, etc., while other species, such as the Skylark, Meadow- 
pipit and Snipe, are comparatively abundant. It is also in 
moors of this type that we are most likely to find a Black- 
headed Gull colony, with which is frequently associated, but 
in infinitely smaller numbers, the Lesser Black-backed Gull. 
ASSOCIATIONS OF THE DRAINAGE-SYSTEM. 
Taking in turn the leading associations of this group, we 
may commence with the streams. Of these, there are two 
main types, the Highland and Lowland, the former charac- 
terised by its rapid flow and rocky bed, and the latter, 
flowing as it commonly does through glacial drift, with a 
gentler fall and less plentiful outcrop of rock and with its 
banks bearing a more luxuriant vegetation. Certain species, 
such as Grey Wagtail and Dipper, are common to both, but 
their numbers, especially in the case of the Dipper, are 
frequently affected in the Lowland type by a scarcity of 
nesting-sites. The Sandpiper is likewise characteristic of both, 
but is absent from the smaller streams. More exclusively 
belonging to the Highland type is the Goosander, on the 
larger rivers, and, where extensive shingle beds are a feature, 
the Oyster-catcher and Ringed Plover. The Lowland stream 
in its turn has a greater charm for the Kingfisher, and the 
Waterhen is much more plentiful. The comparative abund- 
ance of the Sedge Warbler depends upon the luxuriance or 
otherwise of the bank-vegetation, and the bird therefore 
tends to have a more dominant position on the Lowland 
burn or river. 
The lochs fall into at least four natural series: the deep 
loch of the Highland valley, the shallower, peaty loch of the 
moors, the sea-loch, and the Lowland loch with a fenland 
type of vegetation. In their faunal aspects they are largely 
distinct from one another. The loch of the Highland valley, 
characterised by its depth of water and sandy or gravelly 
