154
THE ESSEX NATURALIST.
NOTE.
Mysis relicta in the Lake District.—The occurrence of the "opossum-
"shrimp," Mysis relicta, deep down in Ennerdale Water in June, 1941, as
recorded by our past-President, Mr. D, J. Scourfield, in Nature of
August 23rd, is of such outstanding interest that, far as is the Lake District
from Essex, it merits notice in our Journal,
The original discovery was accidental, a single living specimen, the
first ever recorded from Great Britain, being found trapped in a funnel
which had been suspended in the lake for the purpose of catching" sediment.
Mysis relicta was first found in 1861 in Scandinavian lakes, and has
since been recorded from lakes in Finland, Northern Ireland, the Caspian,
and from the Great Lakes of North America ; its occurrence in Ennerdale,
at 360 feet above sea-level, raises various questions, both geological and
zoological, since its nearest relative is a marine species which inhabits
the seas around Greenland, Mysis oculata Fab., of which it is probably a
modified form, isolated since the Glacial Period : by some zoologists,
indeed, it is regarded as merely a variety of oculata.
Percy Thompson.
BOOK NOTICE.
A Key to the British Species of Freshwater Cladocera, with Notes
on their Ecology. By D. J. Scourfield , I.S.O., F.L.S., and J. P.
Harding, Ph.D. 50 pp., 1941. 1s. 0d.
This, the fifth of the Scientific Handbooks issued by the Freshwater
Biological Association, worthily upholds the high scientific standard of its
predecessors. Written by our Club's Past-President, in collaboration
with Dr. Harding of the Natural History Museum, and abundantly illus-
trated by explanatory diagrams, it cannot fail to be of the utmost value
to students of the sub-order Cladocera and may be warmly recommended
to all interested in the Entomostraca. The Director of the Association,
Dr. E. B. Worthington, contributes an informative preface.