102 THE scCOrmsh NAGURAIISm 
somewhat speculative line of reasoning, however, I think 
that there is sufficient evidence to show that crexata was 
absent in most of, if not in all, the additional localities until 
comparatively recently. 
The irregular appearance of certain insects is a puzzling 
phenomenon which has long been familiar to entomologists. 
In one season such a species may be found plentifully, 
even abundantly, in its appropriate habitat; then for many 
subsequent years it vanishes entirely from its usual haunts, 
only to reappear under a set of favourable circumstances 
too obscure for our present understanding. A_ typical 
instance of this amongst our British Coleoptera is 4gzala 
rufa, a small Lamellicorn beetle which is found only at 
irregular intervals on the Lancashire and Cheshire coast. 
I merely refer to this type of occurrence in order to point 
out that the reappearance of P. crenata is not of the same 
spasmodic nature, as, in one of its new localities at least, 
it seems to have found a permanent home and has occurred 
regularly, though in varying numbers, at one season or 
another for the last twelve years. 
If the assumption that the insect is at present increasing 
in numbers and extending its range is correct, we may 
expect it to be reported from other and more widely extended 
localities where a suitable habitat exists, and its capture in 
Peeblesshire and in the two last-mentioned Renfrewshire 
localities, which all took place after these notes were originally 
written, helps to confirm this view. In this connection it is 
interesting to find that it has been taken in the south-east 
of Ireland by Mr F. Bullock. This is the first record of 
its occurrence in Ireland, but it has probably been present 
there as a rare insect all along. It is quite possible that 
in Ireland it is undergoing the same expansion in numbers 
and range as in Scotland, and it will be interesting to see 
if it is reported from other Irish localities. 
A word or two about the habits of the species may be 
added for the information of coleopterists who may expect 
to come across it in the course of their collecting. With 
regard to habitat it is found, as already indicated, beneath 
the bark of various trees. It seems to prefer a tree upon 
