CHAP. X.] THE PALZZARCTIC REGION. 197 
Trechus and Peryphus being especially characteristic. Staphy- 
linide abound. Among Lamellicorns the genus Aphodius is 
most characteristic. Buprestide are scarce ; Elateride more 
abundant. Among Malacoderms TZelephorus and Malachius are 
characteristic. Curculionide abound: Otiorhyuchus, Omias, 
. Erirhinus, Bagous, Rhynchites and Ceutorhynchus being very 
characteristic genera. Of Longicorns Callidiwm, Dorcadion, 
Pogonocherus, Pachyta and Leptura are perhaps the best re- 
presentatives. Donacia, Crioceris, Chrysomela, and Altica, are 
typical Phytophaga; while Coccinella is the best representa- 
tive of the Securipalpes. 
North European Islands.—The British Islands are known to 
have been recently connected with the Continent, and their 
animal productions are so uniformly identical with continental 
species as to require no special note. The only general fact of 
importance is, that the number of species in all groups is much 
less than in continental districts of equal extent, and that this 
number is still farther diminished in Ireland. This may be 
accounted for by the smaller area and less varied surface of the 
latter island; and it may also be partly due to the great extent 
of low land, so that a very small depression would reduce it 
to the condition of a cluster of small islands capable of sup- 
porting a very limited amount of animal life. Yet further, if 
after such a submergence had destroyed much of the higher 
forms of life in Great Britain and Ireland, both were elevated so 
as to again form part of the Continent, a migration would com- 
mence by which they would be stocked afresh ; but this migra- 
tion would be a work of time, and it is to be expected that 
many species would never reach Ireland or would find its exces- 
sively moist climate unsuited to them. 
Some few British species differ slightly from their continental 
allies, and are considered by many naturalists to be distinct. 
This is the case with the red grouse (Lagopus scoticus) among 
birds ; and a few of the smaller Passeres have also been found 
to vary somewhat from the allied forms on the Continent, show- 
ing that the comparatively short interval since the glacial period, 
and the slightly different physical conditions dependent on 
