Field Notes. 379 
If I am right, therefore, there is no such thing as a native 
plant in Britain. Our flora has been swept away like that of 
Krakatoa ; but we have arrived at a much later stage of the 
re-peopling in our islands. It seems to me far more interesting 
to watch this process of introduction, change, and spreading 
than to enter into speculations as to what species shall be listed 
as ‘natives, ‘denizens,’ or ‘ colonists.’ No such differences 
exist ; it is all a question of degree. 
Britain, for several thousand years, has been receiving 
colonists from all sources, and the process still goes on. The 
oldest element in our flora, the alpine, occurs on nearly all our 
mountains ; for it once occupied the intervening areas, and it 
does not greatly depend on conditions of soil. The limestone, 
aquatic, and Lusitanian flora, on the other hand, are more 
recent introductions ; they can never have occupied continuous 
areas, and their present distribution is full of singular anomalies. 
These three elements of our flora are steadily growing in import- 
ance, whilst the alpine element is stationary, or tends to die out. 
—-:0: 
MOLLUSCA. 
Arion ater var. albolateralis (Roebuck) at _ Brid- 
lington.—It is interesting to record as showing its eastern 
distribution of an almost full-grown specimen of this western 
form, at the northern end of the promenade, in the above 
place, on September 19th last. The two colours being sharply 
defined, make it a very conspicuous object.— JOHN F. MusHAM, 
Selby. 
(8) 
TRICHOPTERA. 
Limnophilus politus at Tadcaster.—Among some Tr1- 
choptera recently sent to me by the Rev. C. D. Ash, and taken 
by himself at Saxton, near Tadcaster, I was pleased to find 
three specimens of Limnophilus politus, thus adding a second 
known locality for the species in Yorkshire, and another to 
the few records for it in Britain.—Gro. T. Porritt, Hudders- 
field, October 13th, Ig1t. 
==3. 0} == 
BIRDS. 
Guillemot Nesting in Kittiwake’s Nest.—When on 
the Bass Rock in August last, Mr. Campbell, the head light- 
house keeper, showed us where a Guillemot had deposited her 
egg in a Kittiwake’s nest, and reared her young one safely. 
Mr. Campbell had obtained a good though very small photo- 
graph of the bird and her young one in this unusual situation. 
A bird or two usually nest in holes in the walls of the old 
fortifications, where a stone has been displaced ; these are also 
rather unusual sites.—R. FORTUNE. 
Igtr Nov. 1, 
