hole number of the fifty-five
doubtful forms none are established as peculiar British varieties, the
number admitted after so {364} rigorous an examination is about what we
should expect in comparison with the limited amount of speciality we have
seen to exist in other groups. The three American species which inhabit the
extreme west and north-west of the British Isles, but are not found on the
continent of Europe are especially interesting, because they demonstrate
the existence of some peculiar conditions such as would help to explain the
presence of the other peculiar species. Whether we suppose these American
forms to have migrated from America to Europe before the glacial epoch, or
to be the remnants of a vegetation once spread over the north temperate
zone, we can only explain their presence with us and not further east by
something favourable either in our insular climate or in the limited
competition due to our comparative poverty in species.

About half of the peculiar forms are found in the extreme west or north of
Britain or in Ireland, where peculiar insular conditions are at a maximum;
and the influence of these conditions is further shown by the number of
species of West or South European plants which occur in the same districts.

We may here notice the interesting fact that Ireland possesses no less than
twenty species or sub-species of flowering plants not found in Britain, and
some of these _may_ be altogether peculiar. As a whole they show the effect
of the pre-eminently mild and insular climate of Ireland in extending the
range of some south European species. The following list of these plants,
for which I am indebted to Mr. A. G. More, with a few remarks on their
distribution, will be found interesting:--

LIST OF IRISH FLOWERING PLANTS WHICH ARE NOT FOUND IN BRITAIN.

1. _Polygala vulgaris_ (_var._ grandiflora). Sligo.

2. _Campanula rotundifolia_ (_var._ speciosa). W. Ireland.

3. _Arenaria ciliata._ W. Ireland (also Auvergne, Pyrenees, Crete).

4. _Saxifraga umbrosa._ W. Ireland (also Pyrenees, N. Spain, Portugal).

5. ,, _geum._ S. W. Ireland (also Pyrenees).

6. ,, _hirsuta._ S. W. Ireland (also Pyrenees).

7. _Inula salicina._ W. Ireland (Scandinavia, Middle and South Europe).

8. _Erica mediterranea._ W. Ireland (W. France, Spain, Portugal).

9. ,, _mackaiana_ (_tetralix_ sub.-sp.) W. Ireland (Spain).

10. _Arbutus unedo._ S.