284
THE ESSEX NATURALIST
Mr. Williams then explained to the meeting the implication of
certain proposed changes in the Rules of the Club, which had heen
circulated in advance, and proposed that they be accepted. Carried
nem con.
The retiring President, Mr. E. E. Syms, then delivered his Presidential
Address on the Life Histories of some British Crickets, at the conclusion
of which the President offered him the thanks of the Club and declared
the meeting closed.
Sunday, 12th April 1959
This meeting, led by Dr. J. H. Belcher and Mr. A. C. Wheeler, was
attended by about thirty-nine Club members and friends, who spent the
day studying the pond life of two Epping Forest pools. Blackweir pond
was examined in the morning and, after lunch, the party moved down
to Baldwin's Hill pond to continue its labours.
Dr. R. H. Nisbet has provided the following notes on some of the
day's finds. Two aquatic Oligochaetes, Chaetogaster and Aeolosoma,
were identified; several leeches were taken, hut only Haemopsis (Black-
weir pond) could be named. Two flatworms were of interest. Dendro-
coelum lacteum, the white turbellarian, was found in Baldwin's pond.
The other was the plerocercoid larva of the cestode Schistocephalus
solidus, a parasite of the Stickleback. The mollusca were few in species
but provided some points of interest. Limnaea stagnalis was found, with
Planorbis corneus at Blackweir but not Baldwin's pond. On the other
hand the Ear Shell, Limnaea auricularia, with egg nidus, the Lake
Limpet (Ancylus lacustris) and the Plat Trumpet Shell (Planorbis com-
planata) were found only in Baldwin's pond. The little Orb Shell
(Sphaerium) was found in both ponds.
Two amphipod crustaceans, Eucrangonyx and Gammarus pulex, were
collected, together with the isopod, Asellus aquaticus, from Blackweir.
The larvae of the dragonflies Erythromma nais (Zygoptera), Aeschna
cyanea and Libellula quadrimaculata (Anisoptera) were collected and
other insects included adults of the genera Corixa, Ilyocoris, Notonecta
and Gerris, larvae of several species of Caddis flies from both ponds; two
well-grown larvae of Sialis; larvae of Chaoborus, the Phantom Midge
and of Chilonomous, the former from Baldwin's and the latter from
Blackweir ponds. One water mite, Hydrarachna, was collected from
Baldwin's pond.
Three vertebrates completed the day's collection. The Three-spined
Stickleback, Gasterosteus aculeatus, from both ponds, the Smooth Newt,
Triturus vulgaris, and the Palmate Newt, Triturus helveticus, both from
Blackweir pond.
The more notable of the plants collected, and identified by Mr. B. T.
Ward, were Potamogeton natans, Elodea canadensis, Glyceria fluitans,
Hottonia palustris and Iris pseudacorus, all from Blackweir pond; and
Glyceria aquatica (maxima) and Nitella, flexilis from Baldwin's pond.
Dr. J. H. Belcher reports that the dominant algae of Blackweir pond
were species of Spirogyra and Mougeotia, together with the epiphytes
Chaetophora and Bulbochaete sp. The rare green flagellate Vacuolaria
virescens Cienk. (see Jane, P. W. (1937). Some Hertfordshire flagellates,