18 VARIATIONS IN NUMBERS AND HABITAT OF
much depends on accident; nor would it be fair to take
particular notice of what I have seen in places not visited
repeatedly.
I think that some great changes were due to the very severe
winters experienced a few years ago. For example, the number
of living individuals of the common Cardium edule previously
found near the mouth of the Crouch was very great; after the
severe winter of 1894, which killed so many oysters, few could be
found alive, but an enormous number of dead shells were seen.
Also, previously, very fine specimens of the Gephyrian,
Priapulus caudatus, could be obtained from the mud of the Deben
near Waldringfield, but afterwards only comparatively small
individuals, as though the larger had been killed. It, however,
seems doubtful if this explanation will suffice in places where the
water is always tolerably deep. As an example, I may say that
eight or ten years ago, in that part of the Deben, near Ramsholt,
called the Rocks, I was able to collect by dredging fairly numer-
ous fine specimens of the beautiful purple Nudibranch, Eolis
coronata, but latterly I have not been able to obtain them, though
most anxious to do so. They have also become more rare in
other localities where I used to find them, as for example in the
Orwell at Pin Mill, and off Mersea, in what may be looked upon
an almost open sea.
It seems difficult to understand what can have occurred to
influence such a large mass of sea water as in the Stour below
and above Harwich, but yet I have remarked considerable
changes during the last 10 or 12 years. I then found sundry
Nudibranchs, which I have not obtained for years and the
curious worm, Aphrodite aculeata, has become much more rare.
Good small specimens of Loligo media were fairly common, but
latterly they have become more and more scarce. Both there
and in every locality in which I have trawled, the number of
specimens of Sepiola atlantica has also become less and less, year
after year, and, instead of catching dozens, I got only an odd one
now and then. What may possibly have been a distinct small
species of Sabella was at one time abundant in the Pye-fleet by
Mersea, but I have not seen it for some years. On the contrary
in 1899 I caught off Mersea some half score of what are probable
the young specimens of Sepia officinalis, not one of which I
had caught before anywhere along the coast. In some of the