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. /lava 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, for 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) 
T OWARDS the end of January, 1920, w'orkmen 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 
discoverv was sent to the Club, and an invitation was extended 
to its Members to inspect the pit before it w T as 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 towm of Grays, and was conducted by 
