THE NEIGHBOURHOOD OF EDINBUKGH. 467 
ring to the under side of floating leaves, wood, &c. March 
— J uly. 
H. ruficoUis, Samou. StepK Dytis. ruficollis^ Marsh. 
Not so common as the preceding, but not of rare occur- 
rence. Braid Hill marshes» Duddingston Loch. 
Gen. Paelobius. 
P. Hermanni, Leach. Dytis, Hermanni, Marsh. 
Very scarce. Pond at Coates, Sir P. Walker. It has 
been conjectured that this insect did not occur so far to the 
north. It is certainly very scarce in Scotland ; but it may 
be remarked regarding the distribution of aquatic insects 
generally, that there is every reason to believe their range 
to be very extensive. This is no doubt owing, in a great 
measure, to the equable temperature of the medium in 
which they live, which exempts them so far from the mo- 
difying influence of climate ; a fact of which we have a fa- 
miliar illustration in many of the common Dyticidfe con- 
tinuing active throughout the winter, when the cold has 
made other insects torpid. The Dyticus marginalis is 
common in Greenland, and it is dispersed over all Europe. 
According to Latreille, the Dyticus griseus, which is 
found in Provence, Piedmont, and other countries adjacent 
to the Mediterranean, occurs also in Bengal * These con- 
siderations render it not improbable that many of the aqua- 
tic insects, which, as British, have hitherto been regarded 
as confined to the southern parts of the island, may yet be 
added to our Scotch lists. The desideratum most desirable 
to be supplied, is the Hydrous piceus, one of the largest 
native insects. It is common near London, and has been 
found as far north as Newcastle. 
* See his " Introduction a la Geograpliie Generale des Araclinides 
el des Insectes," originally published in the third volume of the " Me- 
moires du Muse'um d'Histoire Naturelle." 
Gg2 
