pots
symmetrically crossing the secondary wing-feather and the larger
coverts. Hence the chequering arises merely from an extension of these
marks to other parts of the plumage. Chequered birds are not confined
to the coasts of England; for {184} they were found by Graba at Faroe;
and W. Thompson[327] says that at Islay fully half the wild
rock-pigeons were chequered. Colonel King, of Hythe, stocked his
dovecot with young wild birds which he himself procured from nests at
the Orkney Islands; and several specimens, kindly sent to me by him,
were all plainly chequered. As we thus see that chequered birds occur
mingled with the true rock-pigeon at three distinct sites, namely,
Faroe, the Orkney Islands, and Islay, no importance can be attached to
this natural variation in the plumage.

Prince C. L. Bonaparte,[328] a great divider of species, enumerates,
with a mark of interrogation, as distinct from _C. livia_, the _C.
turricola_ of Italy, the _C. rupestris_ of Daouria, and the _C.
Schimperi_ of Abyssinia; but these birds differ from _C. livia_ in
characters of the most trifling value. In the British Museum there is a
chequered pigeon, probably the _C. Schimperi_ of Bonaparte, from
Abyssinia. To these may be added the _C. gymnocyclus_ of G. R. Gray
from W. Africa, which is slightly more distinct, and has rather more
naked skin round the eyes than the rock-pigeon; but from information
given me by Dr. Daniell, it is doubtful whether this is a wild bird,
for dovecot-pigeons (which I have examined) are kept on the coast of
Guinea.

The wild rock-pigeon of India _(C. intermedia_ of Strickland) has been
more generally accepted as a distinct species. It chiefly differs in
the croup being blue instead of snow-white; but as Mr. Blyth informs
me, the tint varies, being sometimes albescent. When this form is
domesticated chequered birds appear, just as occurs in Europe with the
truly wild _C. livia_. Moreover we shall immediately have proof that
the blue and white croup is a highly variable character; and
Bechstein[329] asserts that with dovecot-pigeons in Germany this is the
most variable of all the characters of the plumage. Hence it may be
concluded that _C. intermedia_ cannot be ranked as specifically
distinct from _C. livia_.

In Madeira there is a rock-pigeon which a few ornithologist