60 Mr. Alfred Russel Wallace. 
Britain. The little island of Lundy, in the Bristol channel, 
has two insects, one a distinct species, the other a variety only, 
which are peculiar to it, and other restricted areas have species 
and varieties of insects which are peculiar to them. Of 
Mollusca four species only, one of them considered doubtful, 
are peculiar to Britain. 
Of plants, Mr. Wallace enumerated two Flowering Plants, six- 
teen Mosses, and ten Hepatic, which are peculiarly British. 
Of the two flowering plants, one Brewers’ Spotted Rock 
Rose (H. Breweri), is peculiar to Anglesea and Holy- 
head island; the other, a water Dropwort (CZ fluviatilis), 
an umbelliferous plant, is found nowhere but in the 
southern half of ‘England and in one locality in Ireland. 
Great Britain also possesses two plants, both truly indigenous, 
which must have come to it from North America, as they are 
not to be found anywhere except in North America and the 
British isles. These are a small orchid (Spiranthes roman- 
zoviana) which occurs in Ireland, and the Pipewort, (Eriocaulon 
septangulare) which is found in the Hebrides and in Ireland. 
There is no reason at all to believe that these species have been 
artificially introduced, and it is difficult to understand how they 
could have been transported to our shores. Ireland also 
possesses about twenty species of Flowering Plants which are 
not to be found in Great Britain. Many of these are known to 
occur in the south of Europe, and two of them are Arctic or 
Alpine plants. Of the British Mosses and Hepatice, three 
genera of each are not found in any other part of Europe, but 
occur in various parts of South America, and of Africa and 
Asia, and in the mountains of New Zealand. Probably these 
plants, and the twenty species which are peculiar to Ireland 
are the remains of forms, which, in the remote past, were 
spread over the greater part of the globe, and which have been 
enabled to survive in Ireland or Great Britain, by the 
exceptionally mild climate. 
In conclusion, Mr. Wallace pointed out that, as has 
been shown by Mr. Darwin, the rarity of a species is 
one great proof that it is undergoing the process of ex- 
tinction. Species are now, and always have been, liable 
to extinction by their enemies becoming too strong, or the con- 
ditions of life too severe, and hence it happens, that in islands 
where the enemies are less numerous, and the conditions more 
equal, the race is continued, and allowed to survive; and this 
fact should stimulate and encourage naturalists to make a more 
thorough and exhaustive investigation of the animals and 
plants which occur in the numerous islands which surround 
our coast. There is yet a great deal to be ascertained with 
regard to them, and no doubt new species yet to be discovered. 
EE 
