92 THE OCCURRENCE OF CYCLOSTOMA ELEGANS
worth the trouble, as I do not believe that such a collection of Chironomidae exists
in the world.
Many people say that Diptera do not require setting, but I can only say that
I can name ten well-set specimens, while I can dubiously name one unset speci-
men in many critical groups such as Homalomyia, Anthomyia, Empis, Rhamphomyia,
Tachydromia ; in fact in many of them I cannot name an unset specimen without
destroying it. I set Diptera from 1866 to 1870, but then, in consequence of the
immense number of specimens I caught at Rannoch, I gave up attempting to set
them until about 1880, but ever since then I have continued to set specimens, and
to set them more and more carefully.—G. H. Verrall.
ON THE OCCURRENCE OF CYCLOSTOMA
ELEGANS IN A LIVING STATE AT FELSTEAD.
By J. FRENCH ; communicated, with remarks, by W. H. DALTON, F.G.S.
[Read May 17th, 1890.]
I HAVE the pleasure to record the settlement by Mr. French of a
long-disputed question—the continued existence in Essex of
Cyclostoma elegans. The abundance of this beautiful shell in many
of the alluvial deposits of the county has exercised the minds of
several members of the Club for years past, and hopes of its being
found living have been excited thereby. At Easter Mr. French told
me that an old resident of Felstead remembers collecting them freely
sixty years ago. On examination of some newly-found specimens,
we found the putrescent animal in the shells, proving recent death;
later, Mr. French learnt that it is to be seen alive in the summer,
and lastly, on the 5th of May he himself saw a dozen in the space of
half as many yards. He sends the following note, with specimens:—
" This mollusc is now confined to an area near Stebbing Ford,
less than 100 yards in its greatest diameter. It occurs nearly at the
line of junction of the alluvium with the rising land, but sufficiently
above the alluvium to shew that it cannot possibly be connected
with it. It is, however, intimately connected with a deposit of
carbonate of lime originally laid down by a spring which rises at a
little higher elevation. Agriculture has now confined this spring to
a narrow channel, and so it happens that the carbonate of lime now
occupying the whole of the area on which Cyclostoma lives is nearly
or quite dry. Beyond the limits of this carbonate of lime not a
single specimen of Cyclostoma is to be found. This calcareous