524 



0. Stapf. 



division, whilst the remaining divisions in the South, the western to Mayo 

 West, and the eastern to Duhlin, count 12 to 17 of them. The bulk of 

 the Mediterranean species shows a similar distribution, although their num- 

 ber is as we have seen much smaller. 



Very striking is the result if we classify the Atlantic and Mediter- 

 ranean elements from the ecological stand-point. Of the species which 

 inhabit bogs or boggy places, wet meadows or wet rocks more than four 

 fifths belong to the Atlantic group and the same holds good for the heath 

 plants. On the other hand, of those found in woods or bush-formations 

 about one half is Atlantic, the other Mediterranean, whilst those confined 

 to pastures and light soil generally are, almost without exception, Mediter- 

 ranean. The ecological contrast between the two classes which constitute 

 the southern element could hardly find a more decided expression. Just 

 as the areas of nearly all the littoral species among the southern element 

 join on to the respective continental areas, in a way which is easy to 

 understand, so also do the areas of most of the southern non-littoral plants 

 of the British Isles. Out of the total of 95 of this class 



10 (Atl. 8, Medit. 2) reach Southern Norway. 



31 (Atl. 12, Medit. 19) > Belgium or Holland. 



32 (Atl. 15, Medit. 17) > Normandy. 

 7 (all Mediterranean) ^ Brittany. 



Thus of the insular areas 85 p. c. of the total are separated from the 

 continental areas only by the width of the Channel plus their distances 

 from the Channel, distances which lie over land, or in the case of the 

 Irish plants also, over the Irish Sea. Of the remaining lop. c. the northern 

 limits of Euphorbia liiberim in the department of the Sarthe (48^) and 

 of Daboecia polifolia (47^^ 30') in that of the Maine et Loire are .in the 

 latitude of Britany, but to the east and south east of that peninsula; that 

 of Echhnu plantagineum is in the Vendee (46^ 30'), and that of Erica 

 mediterranea in the department of the Gironde (45"), whilst a further step 

 of less than 2 degrees brings us to the latitude of the Pyrenees and the 

 North Spanish mountains which harbour a number of plants whose British 

 stations are the only ones north of that latitude. They are Arabis stricta^ 

 Hypericum ttndulatiim^ Snxifraga Geiim^ S, umbrosa^ Physo- 

 spermum cornubiense^ Pinguicitla gr audi flora, Erica Mackaii^ 

 Ncotinca intacta^ Allium triquetrum, Trichomanes radicans. 



It is this small group which, with some justification, might be desig- 

 nated as >Pyreneanc or ^Cantabrianc. One of the plants, Allium triquC' 

 trum^ a Mediterranean species, is a very doubtful native of England, whilst 

 Physospermum cornubiense and Neotiiwa intacta have a wide range in 

 the Mediterranean region. Arabis stricta inhabits a very much broken up 

 area in Southern France (from the Pyrenees to Savoy) and in Spain. HyP^" 

 ricum uiidulatum is considered by some botanists as approaching so 



i.^ 



,-! 



