232 RIKARD STERNER 



Brandenburg 7, South Sweden 13, Westphalia 11, Northern France 40, South- 

 Eastern England 57). 



The defects in the uniformity appear most evidently in a comparison between 

 the East and the West European districts. The continental and maritime elements 

 stand out clearly. A Central or a South luiropean flora element, howe\er, can 

 also easily be distinguished. 



How far are the defects in the uniformity caused by the unequal distribution 

 of continental species.' A comparison between the East and the West European 

 floras shows that the species in the former are fewer in number than those in 

 the latter. This indicates that continental species are inferior in numbers to ma- 

 ritime ones. The central districts, where both elements are represented, have 

 generally many more species in common with the West European districts than 

 with those of East Europe. Hence the maritime element in tliesc districts is 

 preponderant. 



The table also shows the number of continental species in each special 

 district. It may be stated that many species in a certain district lacking in a 

 more westerly one belong to continental species. Silesia has 284 s])ecies that 

 do not occur in Westphalia, and of these 12,5 are continental. As the continental 

 species of a more westerly district are generally found in a more easterly one, 

 we are able to get a more exact idea of the role of the continental element, 

 compared with others. If we compare the flora of Silesia with that of South 

 Sweden, we shall find that the chief difference is not to be traced back to the 

 continental element. In spite of this it cannot be denied that this element is 

 rather conspicuous. Silesia has 304 species that do not occur in South Sweden, 

 and of these 75 are continental. When the districts are situated in an almost 

 straight easterly — ^westerly line from one another, the role of the continental 

 element is naturally greater. As regards Silesia and Northern France, for in- 

 stance, we get the figures 257 and 141. But the number of species in the South 

 Swedish flora which are not found in that of Northern France, is to no small 

 degree formed by continental species: viz. 66 species out of 152. 



The total number of continental species in the districts is probably about 350, 

 i. e. 20% of all the species of the districts. The number of continental species 

 in the whole of the region in (.jucstion, in fact, the whole of Middle Euroj:)e, Czecho- 

 slovakia and Austria excluded, is probably not very much greater. For Hercynia 

 (i. e. the whole of Central Germany, according to Drude, 1902), where the con- 

 tinental flora is well represented, we get only 25 species that are to be looked 

 upon as new; and for Central Russia Herder includes only 40 species not counted 

 before. A few new species may be added, but the whole number of them will 

 hardly exceed 80. Hence in this part of Middle Europe the flora counts about 

 430 continental species. 



