THE ESSEX FIELD CLUB. 105
VISIT TO THE WALTHAMSTOW RESERVOIRS OF
THE METROPOLITAN WATER BOARD.
Saturday, 26th June 1909.
A meeting was held on this afternoon at the Reservoirs by kind permission
of Colonel Bryan, the Engineer to the Board. The principal object of the
meeting was to afford the Conductors opportunities of demonstrating the
interesting forms of aquatic insects, pond-life, and water-plants which occur in the
Reservoirs and surrounding rivulets.
The "Conductors" were Mr. D. J. Scourfield, F.R.M.S., Mr. F. Enock,
F.L.S., Mr. Joseph Wilson, F.R.M.S., Mr. Miller Christy, F.L.S., Mr.
Henry Whitehead, B.Sc., Mr. W. Cole, and others. Mr. Robert Paulson,
F.R.M.S., acted as Botanical Referee.
A tent was set up in the grounds, and tables were placed at convenient spots
to allow of temporary aquaria being formed from glass jars and tubes, and during
the afternoon a large number of interesting water-plants and organisms were
shown.
The most noticeable feature of the vegetation growing on the banks between
the reservoirs was the great abundance of Silent Cucubalus Wibel (inflata of
Smith). It is the dominant plant in early July. This plant is not common
outside the enclosure, but within it appears to have found a very suitable soil.
Most of the plants were quite characteristic of the Hackney Marshes and fields
about Walthamstow. They include Armoracia amphibia Peterman, Stachys
palustris L., Phalaris arundinacea L., and Carex acutiformis Ehrhart. Two
interesting plants found sparingly at a very little distance outside the Water-
works, Erysimum cheiranthoides L. and Apera spica-venti Beauvois, although
searched for, were not found. Butomus umbellatus L. was in flower in a small
pond.
A collection of named grasses and sedges, with several other plants collected
during the afternoon within the grounds, was exhibited on the tables provided for
that purpose.
In searching for aquatic insects, etc., Mr. Enock found that the water in the
reservoirs was much too clean for the naturalist, and very few forms were
noticed. Nepa cineraria, commonly known as the "Water-scorpion," and its
nymphs were found. There were swarms of Chironomous viridis and larvae.
Tanypus zonatus was observed. On the herbage and bushes Hemerobius nerosa
(one of the Lace-winged flies), the aphis-feeding larvae of another," lace-wing,"
Chrysopa perla, and the spider, Epeira cucurbitina, occurred.
The most interesting aquatic organisms observed are noticed in Mr.
Scourfield's speech, which is fully reported below.
Great Crested Grebe.—Mr. Miller Christy observed at least two pairs of
Great-crested Grebes (Podiceps cristatus) swimming about, and pointed out one
bird sitting upon its nest on the bare shore of one of the islands. Its white
breast was very conspicuous from the path on the top of the bank between the
two reservoirs, at a distance of, perhaps, two hundred yards. Probably,
however, the nest was quite safe from molestation, unless by the servants of the
Water Company, who have orders, no doubt, not to molest it. The position
was a somewhat unusual one for the bird to nest in; for it usually nests quite in
the open, almost on a level with the surface of the water, in some shallow part of