342 GEOGRAPHICAL DISTRIBUTION 
Other instances there are in which British-born examples of 
species common to the Continent are, though in a less degree, 
distinguishable from those of neighbouring countries. The Coal- 
TitMovsE of England is to be recognized from that of Europe, Parus 
ater, and accordingly by some ornithologists it is regarded as a 
distinct species, P. britannicus; but the scanty remnants of the 
ancient pine-forests of Scotland are inhabited by birds between 
which and continental specimens no difference can be established. 
The homebred Bottle-TirmousE of Britain, too, has, from its 
darker coloration, been accorded specific rank; but it is now 
known that birds of this species, Acredula cauduta, from southern 
and central Europe vary in this respect, and the specific validity 
of the British form, 4. rosea, can hardly be with consistency main- 
tained. Indeed, as a matter of fact, nearly all of our smaller birds 
can be distinguished by an expert from their continental brethren, 
and this mainly through the duller or darker plumage of the 
former.’ The difference is by no means so great as obtains in the 
birds of the Atlantic Islands above mentioned, but it exists to a 
greater or less degree, and it is certain that an analogous state of 
things is observable in regard to some of the birds of Japan, a 
country which is subject to many of the game climatic conditions 
as the British Islands. It will be for future investigators to deter- 
mine the cause of this similarity, it is enough here to record the 
fact ; but another remarkable instance of the forms of the western 
portion of the Subregion being repeated in the far east is found in 
the range of the two kindred species of the genus Cyanopica— 
the Blue Pre of Portugal and Spain, C. cooki, being replaced in 
Amoorland and Japan by one, C. cyana, so closely allied that some 
authorities have refused to acknowledge their distinctness, and 
yet throughout 130° of longitude no representative of either is 
found.” 
Here it would be convenient to refer to the subject ot local 
variation, which is, however, of general application, though it has 
naturally received most notice in regard to the Birds of the Hol- 
arctic Region. ‘The questions it involves were treated many years 
1 The difference is of course most striking if specimens of brightly-coloured 
species be compared—for example, the Chaffinch or the Yellow-Hammer. 
2 A well-known writer has declared the ‘‘obvious” explanation of ‘‘ this 
anomalous fact” to be ‘‘that the Chinese Blue Magpie was brought from China 
to Spain, precisely in the same manner as the Chinese Ringed Pheasant was 
introduced into England.” No evidence in support of this assertion being 
adduced, charity forbids my here naming the author or his work. Should he 
ever turn his attention to Mammals he will perhaps account for the interrupted 
distribution of the genus 7'apirus by suggesting that the Portuguese carried 
T. indicus from the Malay countries to Brazil, where ‘‘in consequence of the 
greater rainfall” it may have ‘‘ become browner” and the adult indeed have lost 
its picbald coloration ‘‘ by protective selection.” 
