9© PROCEEDINGS OF THE 



Cork AVest) the Atlautic forms number 18 to 21 species per 

 division, wliilst the remaining divisions in the south, the western 

 to Mayo AV'e.st, and tlie eastern to Dubhn, count 12 to 17 of them. 

 The bulk of the Mediterranean species shows a simihir distribution, 

 although their inuiiber is, as we have seen, much smaller." 



Ecoloi/ic((l different iatio)i of the Soutliern Element. — In my 

 original ])a|)er I have attempted to characterise approximately the 

 ecological character of the conditions under which the plants are 

 found in the more southern main-portions of their area. If wo 

 classify the Southern element on that basis, distinguishing 

 between its Athmtic and Mediterranean components, a very 

 striking result is obtained, so striking indeed that no reference to 

 the inherent crudeness of this classification can upset it. It 

 reveals a deep and very general contrast between the hygrophilous 

 species which inhabit liogs or boggy places, wet meadows or wet 

 rocks and heaths on one side, and the more xerophilous tenants 

 of hght, open soih Of the 33 species referable to the hygrophilous 

 type all but two are Atlantic ; of the 50 species of the xeropliilous 

 group, all but eight are Mediterranean. These xero])hils are to 

 two fifths littoral, but the proportion of Atlantics and Mediter- 

 raneans among them is practically the same. Among the cliff and 

 rock plants, and then again among the plants found in woods or 

 bush formations, the Mediterraneans outnumber the Atlantics 

 slightly. The same is the case among the aquatic and semi- 

 aquatic inland-])lants, whilst the two elements are exactly 

 balanced among the Southern elements of the littoral salt marshes. 



British and Continental areas. — A glance at the inset maps (1-3) 

 shows the practical continuity of the British and Continental 

 areas inhabited by the Southern elements as a whole and also by 

 each of its components. It is true the English and the Irish 

 Channels cut info it, but they are not able to interrupt the natural 

 trend of the belt of Southern elements that skirts the Bay of 

 Biscay. The Straits of Dover have opened the door to the 

 Southern littorals, many of which have thus been enabled to creep 

 round the south-eastern comer of England and up the east coast, 

 whilst the general softening of the c-limate due to the separation 

 from the continent has favoured a similar influx of Southerns of 

 the inland type in the same direction. The continuity of the 

 group areas, whether Southern, Atlantic, or Mediterranean, is 

 reflected in the majority of the individual areas of which they are 

 built up. Among the littorals this is true of all but 3 spefies,and 

 among the translittorals of not less than 85 per cent. They are 

 separated from the continental areas only by the width of the 

 Channel plus their distances from the Channel, distances which 

 lie over land except in the case of the Irish plants. Instances of 

 a high degree of continuity of area, and at the same time very 

 typical of each of the component i-lasses of Southerns, are shown in 

 map 4 {Corydalis claviculata)* and map 5 {liahia lyeregrina). 



* In this paragraph the Atlantic species are printed in spaced-out type. 



