olea Nevicensis Scotland.
21. Jungermannia Doniana Scotland.
22. Cesia crenulata Ireland, Wales.
23. Chasmatocolea cuneifolia Ireland.
24. Aerobolbus Wilsoni Ireland, S. America, New Zealand.
25. Petalophyllum Ralfsii Ireland, Cornwall, Devon.

{367}

Many of the above are minute or obscure plants, and are closely allied to
other European species with which they may have been confounded. We cannot
therefore lay any stress on these individually as being absent from the
continent of Europe so much of which is imperfectly explored, though it is
probable that several of them are really confined to Britain. But there are
a few--indicated by italics--which are in a very different category; for
they belong to genera which are altogether unknown in any other part of
Europe, and their nearest allies are to be found in the tropics or in the
southern hemisphere. The four non-European genera of mosses to which we
refer all have their maximum of development in the Andes, while the three
non-European Hepaticae appear to have their maximum in the temperate
regions of the southern hemisphere. Mr. Mitten has kindly furnished me with
the following particulars of the distribution of these genera:--

BARTRAMIDULA. Asia, Africa, S. America and Australia, but not Europe or
N. America.

STREPTOPOGON is a comparatively small genus, with seven species in the
Andes, one in the Himalayas, and three in the south temperate zone,
besides our English species.

DALTONIA is a large genus of inconspicuous mosses, having seventeen
species in the Andes, two in Brazil, two in Mexico, one in the
Galapagos, six in India and Ceylon, five in Java, two in Africa, and
three in the Antarctic Islands, and one in Ireland.

HOOKERIA (restricting that term to the species referable to
Cyclodictyon) is still a large genus of handsome and remarkable mosses,
having twenty-six species in the Andes, eleven in Brazil, eight in the
Antilles, one in Mexico, two in the Pacific Islands, one in New
Zealand, one in Java, one in India, and five in Africa--besides our
British species, which is found also in Madeira and the Azores but in
no part of Europe proper.

These last two are very remarkable cases of distribution, since Mr. Mitten
assures me that the plants are so markedly different from all other mosses
that they would scarcely be overlooked in E