PARIDA, Iol 
THE LONG-TAILED TITMOUSE. 
ACREDULA CAUDATA (Linneus). 
The Long-tailed Titmouse is one of those species which exhibit 
a strong tendency to variation under climatic or other conditions ; 
and ornithologists must exercise their individual discretion in classing 
each form as a race, a sub-species, or a completely segregated 
species. In the adult bird found in Scandinavia, Northern Germany, 
Austria and Russia—extending across Siberia to Japan—the head is 
white ; the purity and extent of that colour attaining the maximum 
in the far north. This is the true 4. caudata, as restricted by some 
authors, which has been obtained once in Northumberland, and 
which seems to have occurred in some of the Scottish forests ; while 
intergradations between this and the next form have been observed. 
In the Netherlands, Germany west of Cassel, and part of France, 
A. caudata meets and interbreeds with the form which represents it 
generally in the British Islands, and which is distinguished by its 
duller tints as well as by having the white on the head restricted 
to the crown. If separated specifically, this dull form is A. rosea. 
In the south of France and the north of Italy, the latter meets 
and intergrades with the greyer-backed A. zrdit, which becomes 
the representative in Sicily and Spain. Although it is difficult to 
