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- 

 TiTMOUSE 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 - Titmouse of Britain, too, has, from its 

 darker coloration, been accorded specific rank ; but it is now 

 known that birds of this species, Acreclida caudata, from southei-n 

 and central Europe vary in this respect, and the specific validity 

 of the British form, A. 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 same 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 Pie of Portugal and Spain, C. cooki, being replaced in 

 Amoorland and Japan by one, C. cijana, 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 oi 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 



^ The difference is of course most striking if specimens of brightly-coloured 

 species be compared — for example, the Chaffinch or the Yellow-Hammer. 



■^ 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 Tapirus by suggesting that the Portuguese carried 

 T. ivdicus 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 piebald coloration "by protective selection." 



