CHAP. II.] THE ELEMENTARY FACTS OF DISTRIBUTION. 19 



farther north in Canada, while five more extend to the borders 

 of the Arctic zone. 



The species of Tits as illustrating areas of distribution. — In our 

 own hemisphere the overlapping of allied species may be well 

 illustrated by the various kinds of titmice, several of which 

 are among our best known English birds. The great titmouse 

 {Parus major) has the widest range of all, extending from the 

 Arctic circle to Algeria, Palestine, and Persia, and from Ireland 

 right across Siberia to the Ochotsk sea, probably following the 

 great northern forest belt. It does not extend into China and 

 Japan, where distinct species are found. Next in extent of 

 range is the coal tit {Parus ater)^ which inhabits all Europe 

 from the Mediterranean to about 64° N. latitude, in Asia Minor 

 to the Lebanon and Caucasus, and across Siberia to Amoorland. 

 The marsh tit {Parus palustris) inhabits temperate and south 

 Europe from 61'' N. latitude in Norway to Poland and South- 

 west Russia, and in the south from Spain to Asia Minor. Closely 

 allied to this — of which it is probably only a variety or sub- 

 species — is the northern marsh tit {Parus horealis), which over- 

 laps the last in Norway and Sweden, and also in South Russia 

 and the Alps, but extends further north into Lapland and North 

 Russia, and thence probably in a south-easterly direction across 

 Central Asia to North China. Yet another closely-allied species 

 {Parus camtschatkensis) ranges from North-eastern Russia across 

 Northern Siberia to Lake Baikal and to Hakodadi in Japan, thus 

 overlapping Parus lorealis in the western portion of its area. 

 Our little favourite, the blue tit {Parus cceruleits) ranges over 

 all Europe from the Arctic circle to the Mediterranean, and on 

 to Asia Minor and Persia, but does not seem to pass beyond the 

 Ural mountains. Its lovely eastern ally the azure tit (Parus 

 cyaneus) overlaps the range of P. cceriileus in Western Europe as 

 far as St. Petersburg and Austria, rarely straggling to Den- 

 mark, while it stretches all across Central Asia between the 

 latitudes 35° and 56° N. as far as the Amoor valley. Besides 

 these wide-ranging species there are several others which are 

 more restricted. Parus teneriffm, a beautiful dark blue form of 

 our blue tit, inhabits North-west Africa and the Canaries ; Parus 

 ledouci, closely allied to our coal tit, is found only in Algeria ; 



c 2 



