e that
many of them are really confined to our island. At the same time we must
not apply this argument too rigidly, for the very day before my visit to
Mr. Stainton he had received a letter from Professor Zeller announcing the
discovery on the continent of a species of our last family, Pterophorina,
which for more than forty years had been considered to be exclusively
British. This insect, _Platyptilia similidactyla_ (_Pterophorus
isodactylus_, Stainton's _Manual_), had been taken rarely in the extreme
north and south of our islands--Teignmouth and Orkney, a fact which seemed
somewhat indicative of its being a straggler. Again, seven of the species
are unique, that is, have only been captured once; and it may be supposed
that, as they are so rare as to have been found only once in England, they
may be all {351} equally rare and not yet found on the continent. But this
is hardly in accordance with the laws of distribution. Widely scattered
species are generally abundant in some localities; while, when a species is
on the point of extinction, it must for a time be very rare in the single
locality where it last maintains itself. It is then more probable that some
of these unique species represent such as are almost extinct, than that
they have a wide range and are equally rare everywhere; and the peculiarity
of our insular climate, combined with our varied soil and vegetation, offer
conditions which may favour the survival of some species with us after they
have become extinct on the continent.

Of the sixty-nine species recorded in my first edition fourteen have been
since discovered on the continent, while no less than twenty-two species
and eleven varieties have been added to the list. As we can hardly suppose
continental entomologists to be less thorough collectors than ourselves, it
ought to be more and more difficult to find any insects which are unknown
on the continent if all ours really exist there; and the fact that the list
of apparently peculiar British species is an increasing one renders it
probable that many of them are not only apparently but really so. Both
general considerations dependent on the known laws of distribution, and the
peculiar habits, conspicuous appearance, and restricted range, of many of
our species, alike indicate that some considerable proportion of them will
remain permanently as peculiar British species.

We will now pass on to the Coleoptera, or beetles, an order which has been
of la