106
THE ESSEX FIELD CLUB.
a lake or reservoir. Probably the unusual site selected by the bird was due to the
fact that, in these very deep reservoirs, there is no shallow place suited to its
needs. Mr. Christy says that this bird, formerly quite uncommon, has increased
surprisingly all over the Midlands and the South and East of England during
the last twenty-five years. In Essex, twenty years ago, when he published his
Birds of Essex (1890), it was so rare as a breeding species that he was able to
indicate (p. 275) only one place at which it had bred—namely, near Walton-on-
the-Naze in 1888. Since then, it has increased steadily, until now there is
scarcely a large sheet of water in the county on which it has not bred; while on
many of these at least one pair breeds almost yearly.
Tea was taken in the tent, and afterwards a short Ordinary Meeting (the
274th) was held, Prof. Meldola, F.R.S., Vice-President, in the chair.
New Members.—The following were elected members of the Club:—Mr.
Oswald Collier, The Hermitage, Snaresbrook, Essex, and Mr. Drury F.
Thompson, 38, Knox Road, Forest Gate, Essex.
A very interesting talk took place on the various observations of the after-
noon, carried on by the Chairman, Mr. Wilson, Mr. Enock, Mr. Whitehead,
Mr. Paulson, and others present. The objects found were shown in glass-jars
and under the microscopes. Mr. Scourfield reported somewhat fully on the.
aquatic organisms found, and his remarks were so interesting that we give a
report, revised by himself:—
Remarks on the Entomostraca and other Aquatic Organisms
Found.—The best find of the afternoon was undoubtedly the (Entomostracan
Leptodora, a number of specimens of which had been secured by means of a
comparatively coarse net (mesh 40 to 1 inch) thrown out from the bank of one of
the reservoirs. With the exception of a single individual taken in the same way
in the same place last year (Sept., 1908), upon the occasion of the visit of the
Quekett Microscopical Club to the reservoirs, this species had not been previously
seen in Essex or, indeed, anywhere in East Anglia. The nearest locality where it
was known to be at home was in one or two of the reservoirs at Tring, although
Mr. Rousselet some years ago had taken a single specimen in the Regent's Canal
at Regent's Park. The water in the Canal, however, might very well have been
derived in part from the Tring reservoirs, which were used for supplying the
Grand Junction Canal, which, in its turn, communicated with the Regent's
Canal.
As would be seen from the specimens exhibited, Leptodora was an
exceedingly hyaline creature—so hyaline in fact that, although about half-an-inch
long, it could only be detected by close scrutiny when in a normal Healthy
condition. Its structure was very peculiar in many respects. Most of its
essential organs were similar to those in a common Water-flea (Daphnia), but
there were profound differences in their arrangement. There was no shell and the
body was straight and much elongated, while the swimming antennae (2nd pair)
were enormously developed. The very beautiful compound eye was situated on a
kind of "conning-tower," formed by the prolongation of the head. The legs,
which were all adapted (or seizing and holding prey, were bunched up close to
the mouth. More remarkable still, the stomach was situated in the tail. A
most significant fact in connection with the development of Leptodora, first
brought to light by Prof. G. O. Sars, was that the young which hatched from
the winter-eggs emerged as "nauplii." It was true that many crustacean types
commenced life as free-swimming nauplii, but Leptodora was the only instance