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THE OCCURRENCE IN ESSEX OF A SPECIES
OF WOODLOUSE (ISOPODA) NEW TO
BRITAIN (PORCELLIO RATZBURGI, BRANDT.)
By WILFRED MARK WEBB, F.L.S.
[Read December 16th, 1899.]
HAVING dealt in the Essex Naturalist with the Land and
Freshwater Shells of the county in some detail, there seemed
to be no likelihood of my making any contribution of importance to
the Club upon that subject for some time to come. I, therefore,
at our worthy Secretary's request, turned my attention to the
collection of Centipedes and Millipedes, classes in which I had
already taken a considerable amount of interest. At the same
time it was by no means difficult to secure land Isopods, and it
seemed as if the study of our Essex Woodlice might produce an
addition to our knowledge of the county fauna, with less labour,
owing to the smaller number of species.
Being doubtful of some of my determinations, I submitted a
number of Isopods to the Rev. Canon Norman, M.A., F.R.S.,
who had kindly offered me his assistance. The result was that
a specimen of Porcellio was considered by that authority to be
Porcellio ratzburgi, Brandt, but its antennae being damaged it
could not be absolutely determined. Other examples from
another locality were too young to make quite sure of, but the
species is one, said Canon Norman, that there is reason to think
might be found in England. Subsequently I have been through
my material from Warley and Brightlingsea, and have picked
out two additional specimens from the former locality, after
careful examination of the supposed Porcellio ratzburgi. Canon
Norman now tells me that they belong to that species, which has
not hitherto been recorded from this country, and I had the
pleasure of exhibiting the two woodlice at the meeting of the
Club at the Geological Museum, on December 16th. The locality
is Warley, and possibly also the species occurs at Brightlingsea,
though only immature examples, if any, are in my collection from
the latter place. It has been found in Norway, Germany, and
France.
[Owing to the interest of this observation of Mr. Webb's, it
seems desirable to publish his note here, somewhat in
advance of order of date.—Ed.]