xl INTRODUCTION. 
These six species are very unequally distributed in Ireland, 
for while the Arbutus, Saxifraga Geum and Juncus tenuss are 
almost confined to the southern half of Kerry and the ad- 
joining portion of west Cork, the Pinguicula is found over 
an area embracing the larger portion of both these counties, 
the Sisyrinchium has a range of fully 220 miles, occurring at 
intervals from Schull in Co. Cork to Killybegs in south Donegal, 
and Saxifraga umbrosa extends along the south and west from 
Waterford to Donegal, a range which would most probably be 
continuous were it not for the strongly calcifuge tendency of 
the plant which excludes it from the limestone regions of Clare 
and Galway. 
On examination, these six plants are found to belong to two 
widely separated and almost antagonistic floras although they 
now grow actually side by side in Kerry. The first four 
mentioned in the above list have their nearest headquarters to 
Treland in the highlands of northern Spain and Portugal ; they 
are distinctly southern in character and belong to the 
Lusitanian or Cantabrian group of the Irish Flora. The two 
last named species in the list, however, have their headquarters 
across the Atlantic in Canada and the northern states of 
America, and are essentially northern in their distribution. 
If to the Sisyrinchium and Juncus we add Naias flexilis and 
Eriocaulon septangulare, both North American plants occurring 
locally in Kerry as well as elsewhere along the west coasts of 
Treland and Scotland, another small group is formed whose 
presence in Kerry involves points of interest and difficulty 
fully equal to those presented by the Lusitanian group. 
All authorities appear to be in agreement as to the great 
antiquity of both these groups, Prof. Forbes, indeed, considered 
that the Lusitanian was the oldest element in our present 
flora. It probably reached Kerry along a coast-line which was 
continuous from Spain to Ireland, a condition of things that 
a rise of about 600 feet in the present level of the land would 
be sufficient to restore. Such a continuous coast-line is 
supposed to have existed during a portion of the Pliocene and 
throughout the late Pleistocene Age, after which period, first 
Ireland then Britain was cut off from the Continent by the 
sinking of the land go as to effectually isolate these Lusitanian 
invaders. If this remote period be accepted as the time of 
their arrival in Ireland, it implies the survival of these plants 
throughout the prolonged Glacial epoch when the greater 
portion of the British Isles was covered by enormous glaciers 
the marks of which are still abundantly visible even as far 
south as Kerry. By most botanists this Glacial period has 
