60 Proceedimjs. 



the barrier which cut off the northward advance of southern 

 forms at the close of the glacial epoch ; and if an ocean 

 further covered the Sahara and the plains of Central Asia, we 

 can well understand the entire absence from England of 

 South African and South Asiatic types of trees. 



That there has been a very large influx of plants into this 

 island in the course of centuries we have evidence when we 

 compare the flora of Great Britain with that of Ireland, the 

 total number of species m Ireland being barely 1000, or only 

 about two-thirds of the number found in Great Britain. 



Let me quote, in conclusion, a paragraph from an address 

 by J. Gilbert Baker, F.E.S., given to the Yorks. Nat. Union 

 at Selby, on March 3rd, 1883. He says : — -" Upon the general 

 question of evolution, an important light is thrown by studying 

 the flora of Britain in comparison with that of Continental 

 Europe. The most important general character of the British 

 flora is its utter want of any distinctive individuality. Leaving 

 out of count a few doubtful Hieracia, Willows, Paibi, and 

 Roses, I can give only two good instances of British plants 

 that do not occur in Continental Europe. One of these, 

 Potamorjeton lanceolatus, is known in Cambridgeshire, Angle- 

 sea, and the North of Ireland ; the other, Eriocaulon septamju- 

 lare, is found m Skye and Galway ; and, across the Atlantic, 

 it is widely spread in North America. It is now generally 

 believed that Britain was last separated from the Continent 

 towards the close of the glacial period. 



" I do not think any competent authority would consider 

 that it was an extravagant suggestion that Britain may have 

 been an island for a hundred thousand years. If, then, out 

 of 1400 species which it produces, not one is distinct, this 

 is a very significant fact." 



Mr. Crosfield exhibited specimens of many of the rare 

 plants named in his paper. 



Mr. N. E. Brown, of Kew, remarked that our flora is an 

 insular flora. Insular floras are of three types — recent and 

 ancient continental island floras, and oceanic island floras. 

 (1) Those in islands of comparatively recent date, separated 

 from the mainland by seas under 100 fms. in depth ; (2) in 

 islands surrounded by deep seas, such as those of Madeira, 



