Mr. A. Newton's two Days at Madeira. 189 
to the Atlantic Islands—a fact suggestive enough to those who 
are acquainted with the deductions inferred from similar cases 
by Professor Edward Forbes, Mr. Wollaston, and, chief of all, 
Mr. Darwin. 
In connexion also with this topic, I would remind my readers 
of Mr. Wollaston's admirable remarks on the effects of isolation 
and exposure to a stormy atmosphere upon the insect-world *. 
I fully believe that similar effects are to be traced among birds; 
and, if I am not mistaken, the first and most apparent effect of 
the latter cause is an obscuring or darkening of the plumage. We 
have examples of it in our own country. Few of our native 
birds attain the brilliant hues observable in their Continental 
brethren. When do we ever see an English Yellow Bunting 
or a Bullfinch as brightly coloured as a French or, still more, a 
German one ? The dark back of our Pied Wagtail has led it 
to be described as a species distinct from the Continental Mo- 
tacilla alba. Our Long-tailed Titmouse is equally deserving of 
a like recognition. I will say nothing here of the qucestio 
vexata of the difference between Lagopus scoticus and L. albus; 
for in that case probably other causes have come into play. If 
we go to the other extremity of the Palsearctic region, we find the 
same thing occurring. Orites trivirgata differs from the Conti¬ 
nental 0. caudata , just as our own Long-tailed Titmouse does. 
Accentor rubidus bears the same relation to the Continental speci¬ 
mens of A. modularis as our own Hedge-Sparrow. In a word, 
several, perhaps many, British forms are repeated (I do not say ex¬ 
actly, but to some degree) in Japan. If I am right, how can the 
fact be reconciled with the doctrine of the continuity of specific 
areas ? Simply, I imagine, by similar conditions obtaining in loca¬ 
lities so far apart; and the most obvious of these similar condi¬ 
tions I take to be the prevalence in both localities of an insular, 
as opposed to a continental, climate. Mr. Vernon Harcourt has 
already remarked that “ all the birds of Madeira are darker than 
their European brethren;" and I can, of my own knowledge, 
confirm his statement in several instances. The variation here 
observable is very much greater generally than in the case of 
“ Variation of Species,” p. 70 et seq . 
