101
NOTE ON THE RECENT OCCURRENCE OF THE
"FAIRY SHRIMP," CHIROCEPHALUS DIAPHANUS,
AT EPPING.
BY D. J. SCOURFIELD, F.Z.S., F.R.M.S.
[Read 25th January, 1919].
IN Baird's "Natural History of the British Entomostraca,"
published by the Ray Society in 1850, it is mentioned (p. 54)
that Chirocephalus diaphanus had been found "near Epping" by
E. Doubleday. The date of collection is not given, but it can-
not have been later than 1849 (the preface to the "Natural His-
tory" is dated December, 1849), and may very well have been
several years earlier. So far as I know' this old record of seventy
years ago has hitherto constituted the sole notice of the oc-
currence of this beautiful Phyllopod Entomostracan in Essex,
notwithstanding the considerable amount of attention which
has been given to collecting Entomostraca in the Epping Forest
area for many years past.
It was with no little surprise and delight, therefore, that
on the 27th July last (1918), whilst searching for larvae of
Anopheles, I found specimens of C. diaphanus in a small shal-
low pool on the green, opposite the Bell Inn (known as Bell
Common) at Epping. The specimens were not in great abun-
dance and none were fully adult, but nearly all other stages,
except, perhaps, the earlier "nauplius" stages, were present.
They were associated with Daphnia pulex (obtusa form), Cyclops
bicuspidatus and Cypris (Cyprinotus) incongruens, the latter
being particularly abundant. There were also various Insect
larvae present.
Thinking that it would be better to let the Fairy Shrimps
have a chance of developing a little more, I did not take many
specimens, but determined to pay another visit in about a week's
time. This was done, but to my astonishment not a single
example of Chirocephalus could be found after the most ex-
haustive examination of every part of the pool. In nine days
the whole Fairy Shrimp population had entirely disappeared,
although When first seen everything pointed to the develop-
ment of the colony being on the upgrade!
Such an experience is, however, by no means an isolated one.
In Norman and Scott's "Crustacea of Devon and Cornwall,''