272 THE ENTOMOSTRACA OF EPPING FOREST
Cyclops of the " tricuspidatus " group—i.e., either C. bicuspidatus,
C. vernalis, C. languidus, or C. bisetosus. If, as often happens, the
pool contains moss, then Canthocamptus pygmaeus is almost sure to
be present.
Various Duck Ponds. In various places on the
outskirts of the actual Forest are to be found, mostly
by a road-side, a number of little duck - ponds which
deserve mention, as they have contributed three species to
our list not obtained elsewhere. They are, moreover, worthy of
notice from the peculiarly constant facies of their Entomostracan
fauna. The chief of these ponds examined have been two near
Chingford Hatch, one at High Beach village, three at Seward-
stone, one on Theydon Bois Green, and one near the " Volun-
teer." The two peculiarities about this type of pond which
strike an observer at once are the entire absence of weeds, and
the turbidity of the water. The collector of Entomostraca also
finds correlated with these characters the almost invariable
presence of three particular species—namely, Daphnia obtusa,
Cyclops strenuus, and Cypria ophthalmica. Three other species
occur less constantly, but are only to be found in these duck-
ponds, and may therefore also be considered characteristic.
These are Daphnia magna, Cypridopsis villosa, and Cypris incon-
gruens. In addition to the above there may be found occasionally
one or two other species, usually very common forms, such as
Chydorus sphaericus and Cyclops serrulatus.
Males and "Ephippial" Females of Cladocera.
Since the publication of the paper on the Wanstead Park Ento-
mostraca, the males and "ephippial" females of a consider-
able number of additional species of Cladocera have been seen
in the Forest district, and some further information obtained as
to the times of appearance of these forms. The full details,
including the records from Wanstead Park, are given in Table
III., in which each sign (+ or *) represents a distinct record.
In the main, the cycle of seasonal distribution of these sexually
mature individuals, from the whole district, closely agrees with
that already made out in connection with the Wanstead Park
forms. This will be apparent from the following statement of
the number of species found to be producing males and "ephip-
pial" females in each month:—