270 THE ESSEX NATURALIST.
need cause no difficulty as closer inspection will soon show whether
it is due to pigment on the surface or to the underlying alimentary
canal. There is, of course, much variation in the exact outlines
of the pigmented part of the head, but the two figures may be
taken as showing fairly normal conditions.
So far as I know the relation of the two species to one another
and to the environment has not been investigated. Now that a
simple method of distinguishing them is available it is to be hoped
that it will lead to their separate inclusion in a number of future
researches on the ecology of freshwater organisms.
REFERENCES
1. Chilton, C. 1920. Note on the Freshwater Isopods known as
Asellus aquaticicus, Ann. Mag. Nat. Hist., vol. v, p. 200.
2. Cooper, J. Omer. 1925. The Higher Crustacea in Nat. Hist. Wicken
Fen, Part ii, p. 140.
5. Tattersall, W. M. 1920. The occurrence of Asellus meridianus,
Rac. in Derbyshire. Lancashire and Cheshire Naturalist,
p. 273.
THE "RED-HILLS" OF CANVEY ISLAND.
SUPPLEMENTARY NOTES.
By ERNEST LINDER, B.Sc.
NO further sites have been located on the island since the date of the
publication of the results of the work done in 1938,3 but the mounds
at May Avenue and Blackmore Avenue have been further explored.
Excavation at both sites has yielded results of special interest:—
At May Avenue the fragments of crude ware recovered include several
rims and bases of unusual form: the rims are not curved, but straight,
and the sides, where attached to bases, thickened locally at a point that
may be described as a "corner." Taken together, the straight rims and
ill-shaped corners suggest that the fragments belonged to a form of pan,
a type that in some features recalls the shallow evaporating pan described
by Prof. H. H. Swinnerton in his paper on the "Prehistoric Pottery Sites
of Lincolnshire."4 The crude ware generally was glazed externally, and
some lumps of fused "furnace slag" of similar colour and vitreous
composition were found associated with the pottery in the same deposit
Mr. C. Hawkes informs me that some of the better class ware submitted
to him for examination is of Pre-Roman late Iron-Age Belgic Culture.
Occupation of the mound may thus have dated from the early years of
3 Essex Naturalist, vol. xxvi, Part III., p. 136.
4 Antiq. Journ., 1932, p. 240.