154
THE ESSEX NATURALIST.
stripe, and a white chin; its summer home is in north Europe
and north Asia ; of this form, a number of individuals have been
noted on the east and south coasts of England, and amongst other
records, "fair numbers" were seen on migration in Fair Isle,
in 1908, 1909, 1910, 1912, 1913; possibly a pair remained to
nest in 1906 on Romney Marsh, Kent. The black-headed wag-
tail, M. flava L. subsp. feldegg (Michalelles) Hartert, is a southern
race, nesting in south-east Europe and Asia Minor, and occasion-
ally straying into western Europe. The male in summer has
the head and ear-coverts black, and all the under-parts yellow.
Four British examples have been seen, in Sussex and Kent,
and another, probably, in Norfolk. The ashy-headed wagtail,
M. flava L. subsp. cinereocapilla (Savi) Ticehurst, is resident in
the Mediterranean region, rarely straying further north ; this
form has a very faint white eye-stripe, grey head, and darker
lores, and white chin and upper throat; the only British record
is of a bird obtained at Penzance.
In the above brief notes, the description remarks refer only
to male birds in summer plumage, fur in winter or in juvenile
plumage most of the different races of yellow wagtail resemble
each other so closely that much experience is needed to distin-
guish them.
RECENT DISCOVERY OF A DENE-HOLE
AT GRAYS.
By PERCY THOMPSON, F.L.S.
(With One Illustration.)
TOWARDS the end of January, 1920, workmen in the
employ of the Grays Chalk Quarries Co. accidentally
broke into an underground pit during quarrying operations.
By courtesy of the Directors of the Company, notice of the
discovery was sent to the Club, and an invitation was extended
to its Members to inspect the pit before it was filled in again.
Accordingly, on February 5th, a party, consisting of Miss
G. Lister, Mr. W. Whitaker, Mr. E. T. Newton, Mr. S. Hazzle-
dine Warren, Mr. F. J. Brand, and the writer, visited the large
quarry belonging to the Grays Chalk Quarries Co., situated
to the north-west of the town of Grays, and was conducted by