58 Mr. Alfred Russel Wallace. 
14.—ON THE PECULIAR SPECIES OF THE BRITISH 
FAUNA AND FLORA. 
By ALFRED RussEL WALLACE. 
[Read March 17th, 1880.] 
Mr. WatLaAceE, in the first place, called attention to the fact, 
now well established, that all large islands which have been 
separated for a long period of time from the mainland, possess 
_species of animals and plants which are peculiar to them, the 
number of peculiar species, speaking generally, being large or 
small, according to the length of time during which the island 
has been cut off from the land of which it formerly formed part. 
He also pointed out that these are very significant facts in con- 
nection with the geographical distribution of animals and plants. 
He further stated that his researches having led him to the 
conclusion that the British islands, although they had only 
been separated from the continent in comparatively recent 
times, were no exception to this rule, he applied to a number 
of distinguished men who had made special studies of various 
departments of zoology and botany, but they one and all gave 
it as their opinion that there were no animals or plants which 
were peculiar to Great Britain, and that probably every species 
to be found in our islands would be found on the continent if 
proper and sufficient search were made for it. Not being 
satisfied with these replies, he proceeded with his investigation, 
which resulted in his coming to the conclusion that there are a 
considerable number of species recorded as occurring in Great 
Britain which are not to be found in any other part of the world. 
Mr. Wallace went on to show that there is much direct 
and positive evidence that the British islands once formed 
part of the continent of Europe, and were formerly more 
extensive than they now are, also that their connection with 
the continent has been broken and again re-established more 
than once, and he went through this evidence in detail. 
He next proceeded to show that the number of species of ani- 
mals and plants which occur on the continent of Europe is much 
larger than the number which is to be found in Great Britain, 
and these again, in their turn, are considerably larger than the 
number of species which have been recorded as occurring in 
Ireland, whilst Ireland again has species which are not to be 
found in Great Britain. Allthisseemedtoshowthat Ireland was 
separated, as anisland, from Great Britain sometime before Great 
Britain ceased to form part of the European continent. With 
regard to the species peculiar to the British islands, it is 
probable that they have all come into existence since the 
islands were last severed from the continent, and the fact that 
