e peculiarity of the soil and water
in the former island, have really led to the production or preservation
of a well-marked variety of insect. In the first edition of this work
two other species were named as then, peculiar to Britain--Setodes
argentipunctella and Rhyacophila munda, but both have now been taken on
the continent.

2. MESOPHYLAX IMPUNCTATUS, _var._ ZETLANDICUS.--A variety of a South
and Central European species, one specimen of which has been found in
Dumfriesshire. The variety is distinguished by its small size and dark
colour.

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_Land and Freshwater Shells._--In the first edition of this work four
species were noted as being, so far as was then known, exclusively British.
Two of these, _Cyclas pisidioides_ (now called _Sphaerium pisidioides_) and
_Geomalacus maculosus_, have been discovered on the continent, but the
other two remain still apparently confined to these islands; and to these
another has been added by the discovery of a new species of Hydrobia in the
estuary of the Thames. The peculiar species now stands as follows:--

1. LIMNEA INVOLUTA.--A pond snail with a small polished amber-coloured
shell found only in a small alpine lake and its inflowing stream on
Cromagloun mountain near the lakes of Killarney. It was discovered in
1838, and has frequently been obtained since in the same locality. It
is sometimes classed as a variety of _Limnea peregra_, and is at all
events closely allied to that species.

2. HYDROBIA JENKINSII.--A small shell of the family Rissoidae
inhabiting the Thames estuary both in Essex and Kent. It was discovered
only a few years ago, and was first described in 1889.

3. ASSIMINEA GRAYANA.--A small estuarine pulmonobranch found on the
banks of the Thames between Greenwich and Gravesend, on mud at the
roots of aquatic plants. It has been discovered more than sixty years.

But besides the above-named species there are a considerable number of
well-marked varieties of shells which seem to be peculiar to our islands. A
list of these has been kindly furnished me by Mr. Theo. D. A. Cockerell,
who has paid much attention to the subject; and after omitting all those
whose peculiarities are very slight or whose absence from the continent is
doubtful, there remain a series of forms some of which are in all
probability really endemic with us. This is the more probable from the fact
that