510 



0. Stapf. 



meaning of the terms ^Atlantic*, »Pyrenean«j or »Lusitanian« plants and 

 the place which these elements hold in the British flora and its history. 

 I have therefore thought it useful to sort out from the British flora that 

 constituent portion which from its distribution in Europe might justly be 

 called >Atlantic« and to analyse it with regard to the relative continuity 

 or discontinuity of the British and Continental areas of its members. In 

 doing so it became evident, as was to be expected, that the »Atlantic< 

 fraction of the flora could not be separated from another portion which 

 whilst covering the Atlantic region extended beyond it into the Mediterranean 

 region of which it is a characteristic part. In fact they belong to the 

 same Southern stock, but with this difference that one is more specialised 

 with respect to the conditions which determine the distribution of its 

 members than the other. The scope of my analysis had therefore to be 

 extended, so as to include both. The former are the >Atlantic« and the 

 latter the > Mediterranean* types as understood in this essay. 



I have not considered it necessary to enter into the question whether 

 these Atlantic and Mediterranean types have survived the Glacial period 

 in Great Britain and Ireland or whether their present habitats in those is- 

 lands are postglacial. Whether one accepts the >land-ice« or the >submer- 

 gence« theory both of which have been dealt with so admirably by Pro- 

 fessor BoNNKY (5) the botanist cannot but assume that survival under the 

 rigorous conditions postulated by both theories was impossible for most 

 or probably all the plants under consideration. If in the future new facts 

 should come to light which make the climatic conditions during the Glacial 

 period appear more favourable for plant life, the question of survival will 

 have to be reconsidered; but at present I see no way out of the conclusions 

 at which Mr. Reid, and many years before him. Professor Engler have 

 arrived. 



The term ^Atlantic type* was formulated by H. C. Watsox in his 

 »Ilemarks on the Geographical Distribution of British Plants* in 1835. 

 There on p. 86 he says: >The Atlantic type embraces species found in the 

 southwest of England or Wales, sometimes very locally, sometimes extending 

 far along the southern or western counties, but rare or wanting on the 

 east coast. Some plants of very limited geographical extension are common 

 to this part of Britain, the west of France and Portugal. Erica cihciris^ 

 Sibtliorpia europaea^ Kiq)horbia Pcplis^ Bartsia viscosa and Pingwcim 

 liisitanica may be given as examples of the type.* From the reference 

 to France and Portugal it might be inferred that he had in view the ge- 

 neral extension of the areas of his Atlantic types over western Europe 

 when introducing the term. But if he had it in view originally, he made 

 it abundantly clear in ^Cybele Britannica* in 1847, that this did not hold 





ood any longer. For he remarks here on p. 51 of the first volume: 

 »These species (i. e. of the Atlantic type) correspond in the one circum- 

 stance of having some decided tendency to the western or Atlantic side 



