79. ,, ,, ,, COMPRESSUS. England. 80. ,, margaritifer, _var._ OLIVACEUS. 81. Anodonta cygnaea, _var._ INCRASSATA. England. 82. ,, ,, ,, PALLIDA. England, Ireland. ESTUARINE OR MARINE PULMONOTRANCHS. 83. ASSIMINEA GRAYANA. Thames Estuary. _Peculiarities of the British Flora._--Thinking it probable that there must also be some peculiar British plants, but not finding any enumeration of such in the _British Floras_ of Babington, Hooker, or Bentham, I applied to the greatest living authority on the distribution of British plants--the late Mr. H. C. Watson, who very kindly gave me the information I required, and I cannot do better than quote his words: "It may be stated pretty confidently that there is no 'species' (generally accepted among botanists as a good species) peculiar to the British Isles. True, during the past hundred years, nominally new species have been named and described on British specimens only, from time to time. But these have gradually come to be identified with species described elsewhere under other names--or they have been reduced in rank by succeeding botanists, and placed or replaced as varieties of more widely distributed species. In his _British Rubi_ Professor Babington includes as good species, some half-dozen which he has, apparently, not identified with any foreign species or variety. None of these are accepted as 'true species,' nor even as 'sub-species' in the _Students' Flora_, where the brambles are described by Baker, a botanist well acquainted with the plants of Britain. And as all these nominal species of Rubi are of late creation, they have truly never been subjected to real or critical tests as 'species.'" In my first edition I was only able to name four species, sub-species, or varieties of flowering plants which were believed to be unknown on the continent. But much attention has of late years been paid to the critical examination of British plants in comparison with continental specimens, and I am now enabled to give a much more {360} extensive list of the species or forms which at present seem to be peculiar. For the following list I am primarily indebted to Mr. Arthur Bennett of Croydon. Sir Joseph Hooker has been so kind as to examine it carefully and to give me his conclusions on the relative value of the differences of the several forms, and Mr. Baker, of Kew, has also assisted with his extensive knowledge of British plants. LIST OF SPECIES, SUB-SPECIES, AND VARIETIES OF FLOWERING PLANTS FOUND IN GREAT BRITAIN OR IRELAND, BUT NOT AT PRESENT KNOWN IN CONTINENTAL EUROPE. BY ARTHUR BENNETT, F.L.S. THE MOST DISTINCT AND BEST DETERMINED FORMS ARE MARKED WITH AN ASTERISK. 1. *Caltha radicans (Forst.). "A much disputed species, or form of _C. palustris_. It is a relatively rare plant." (J. D. H.) "Certainly distinct from the Scandinavian form." (Ar. Bennett.)