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 borealis), 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 borealis in the western portion of its area. 
Our little favourite, the blue tit ( Parus coeruleus) 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. coeruleus 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 teneriffce, 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 ° 
