TEMPERATE FLOEAS 



oi 



marked increase of the number in more southern as compared 

 with more northern latitudes. 



I will first show how this law applies even in the com- 

 paratively slight difference of latitude and climate within our 

 own country. Dividing Great Britain (without Wales) ^ into 

 three nearly equal portions — Scotland north of the Forth and 

 Clyde, Mid-Britain, and South Britain, including all the 

 southern counties; with areas of 22,000, 26,000, and 31,000 

 square miles — the number of species (in 1870) was, respec- 

 tively, 930, 1148, and 1230. At the same period the total of 

 Great Britain was 1425 species. These figures are all ob- 

 tained from Mr. H. C. Watson's Cybele Britannica, and must 

 therefore be considered to be fairly comparable. We see here 

 that the whole of the Scottish Highlands, with their rich alpine 

 and sub-alpine flora, together with that of the sheltered valleys, 

 lakes, and mountainous islands of the west coast, is yet de- 

 cidedly less rich in species than Mid-Britain, while both are 

 less rich than South Britain, with its more uniforai surface, 

 but favoured with a more southern climate. 



The following table shows these facts more distinctly : — 



The above figures have been kindly extracted from Wat- 

 son's volume by my friend the late Mr. W. H. Beeby. 



Making a comparison of some countries of Europe we have 

 similar results more clearly shown. 



1 Wales is omitted in order to make the three divisions more equal, and 

 contrasted in latitude only. 



