302 MR. F. BALFOUR BROWNE ON AQUATIC COLEOPTERA. 
of the year, the ponds and ditches still containing water 
are not richer in species or in individuals — they are in fact 
poorer ; the other is that within a few hours of a dried up pond 
being re-filled with water, Beetles appear in it. 
I had noticed in 1904, that ponds dry one week were certain 
to contain Water- beetles the following week if, in the mean- 
time, there had been sufficient rain to produce even a thin 
layer of water on the bottom ; but it was not until last season 
that I endeavoured to discover where these Beetles came from,, 
and my opportunity was especially favourable during my 
stay on Loch Lomond side in Scotland last July. During 
that time I was specially studying the species of Water-beetles 
to be found in the small peaty holes upon the high moors. 
On the mountains, in peaty districts, the rain scours out 
holes and channels in the peat on the flatter parts, and in 
the holes water-beetles are to be found. June, 1905, was par- 
ticularly dry in the Luss district, so that on my arrival at the 
beginning of July the peat holes were mostly dry. I visited 
in particular one hill in the neighbourhood, the top of 
which was about 1000 feet above sea-level, and noticed the 
hollows in the peat which were quite dry and hot with the 
sun. On this first visit, one hole had about a pint of water 
in it and contained about 7 specimens of Hydroporus of 3 or 
4 species ; another hole was damp but overhung with a clump 
of sphagnum, which on squeezing yielded a little water and 
a few beetles. Except for these two places there was no visible 
water upon the patch of ground which I had determined to 
observe. On the night of the nth and the early morning of 
the 12th July, there were about 12 hours’ rain, and the weather 
cleared about 7 or 8 a.m. I re-visited the hill-top the same 
morning and found that all the holes contained water — and 
beetles. Some contained as many as 6 or 7 species including 
Agabus bipustulatus, a fairly large kind, individuals being 
common. Within a few days the water and beetles had 
again disappeared, and it was not until about the 30th of 
the month that heavy rain fell and re-filled the holes, which 
were again promptly tenanted within a few hours after the 
rain. One interesting point in connection with these observa- 
