15. _Sisyrinchium angustifolium._ W. Ireland (North America, Arctic and Temp.). 16. _Potamogeton lonchites._ Ireland, Mr. Arthur Bennett informs me that this is certainly not British or European, but may possibly be identical with _P. fluitans_ _var._ _Americanus_ of the U. States. 17. _Potamogeton kirkii_ (_natans_ sub.-sp.). W. Ireland. (Arctic Europe?) 18. _Eriocaulon septangulare._ W. Ireland, Skye, Hebrides (North America). 19. _Carex buxbaumii._ N. E. Ireland, on an island in Lough Neagh (Arctic and Alpine Europe, North America). 20. _Deyeuxia neglecta_ (_var._ _Hookeri_). On the shores and islands of Lough Neagh. (And in Germany, Arctic Europe, and North America.) We find here nine south-west European species which probably had a wider range in mild preglacial times, and have been preserved in the south and west of Ireland owing to its milder climate. It must be remembered that during the height of the glacial epoch Ireland was continental, so that these plants may have followed the retreating ice to their present stations and survived the subsequent depression. This seems more probable than that so many species should have reached Ireland for the first time during the last union with the continent subsequent to the glacial epoch. The Arctic, Alpine, and American plants may all be examples of species which once had a wider range, and which, owing to the more favourable conditions, have continued to exist in Ireland while becoming extinct in the adjacent parts of Britain and Western Europe. As contrasted with the extreme scarcity of peculiar species among the flowering plants, it is the more interesting and unexpected to find a considerable number of peculiar mosses and Hepaticae, some of which present us with phenomena of distribution of a very remarkable character. For the following lists and the information as to the distribution of the genera and species I am indebted to Mr. William Mitten, one of the first authorities on these beautiful little plants. That of the mosses has been corrected for this edition by Dr. R. Braithwaite, and several species of hepaticae have been added by Mr. Mitten. {366} LIST OF THE SPECIES OF MOSSES AND HEPATICAE WHICH ARE PECULIAR TO THE BRITISH ISLES (OR NOT FOUND IN EUROPE). (_Those belonging to non-European genera in Italics._) MOSSES.