1938 - The Vasculum

23
On one of the Whittle Dene Reservoirs, run off for twelve
months, we took Zonitoides nitidus. This snail has only been taken in V.C.
67 by Alder in Heaton Dene and H. Watson (1890) near Corbridge. There is
one record in 1912 by A. M. Oliver for V.C. 68, at Spindleston. Helix
nemoraiis and H. hortensis swarmed on the banks of one of the reservoirs in
close conjunction, which is very unusual. As an aside: recently the absence
of many Helices on the coast line of the two counties was partly accounted
for by a native who said that he and others were accustomed to cook and eat
these snails. The fact has been strenuously denied, but this confirms the
statement previously made.
Certain incidental observations should be noted. In the Farding
Lake, Whitburn, the bodies of Limnaea peregra were very yellow of an
unusually deep colour, similar to the colour of the Anodontacygncaea taken
in the magnesian limestone area ponds at East Boldon, probably due to the
presence of the limestone. The re-crudescence of Theba cantiana in
Northumberland noted last year has been further and strikingly exemplified.
The presence of' albinism in slugs, especially in the millstone grit area, has
been very marked. A rare form of Arion subfuscus was found in Benridge
Bog. Arion ater albida and alba-lateralis have been fairly frequent,
especially in the west, and at CatcIeugh there was quite a brood of the
albida. Albinism is said by some authorities to be a feature of chalky
districts; others say it is due to dwelling in shady forests, others that it
occurs where the species has reached its horizontal and vertical limit. The
matter needs further investigation and is a good subject for research.
Hydrobia jenkinsi also is spreading steadily in Northumberland. The new
areas are at R. Pont, Berwick Hill, Whittle Dene Reservoir, West
Cramlington and New York near Whitley Bay. In Durham it swarms. This
species simply crowds out other species by its swarming. A very remarkable
Limncea peregra ovata was found in the old Marden Lake at Cullercoats,
heavily impregnated with magnesian lime-stone. The shells were large,
solid, highly polished, very rounded, and had the consistency and almost the
shape of the marine Natica catena-doubtless another effect of the
magnesian limestone.