PARIDA. TOS 
THE COAL-TITMOUSE. 
PARUS ATER, Linnzeus. 
In the Coal-Titmouse, as in the Long-tailed Titmouse, there are 
gradual variations, the extremes of which become, in the opinion 
of some ornithologists, entitled to specific distinction. As Parus 
britannicus, Messrs. Sharpe and Dresser have separated our race 
from that of the Continent, because the upper back is olive-brown 
in the British bird, and slate-grey in the Continental form; but, 
while I admit that a difference in tint is often recognizable, there are 
intergradations, and these are even noticeable in specimens from 
some of the forests of Scotland, in which the bird is abundant. 
Examples from Norfolk—indistinguishable from those of the Conti- 
nent—may, of course, be foreign immigrants; and so may the 
specimens in the British Museum, from Perthshire, which are identical 
with birds from the Vosges, although less purely grey than those 
from Japan. Against the migration-hypothesis must, however, be 
set the experience of Mr. Gurney and the late Mr. Booth, who never 
observed the Coal-Tit at sea off the east coast, nor received a wing 
of it out of numbers sent from the light-ships, as well as the fact 
