102 teansactions of the 



6th July, 1875. 



Mr. James Allan, Vice-President, in the chair. 



The Chairman remarked that the lapwing was a migratory bird 

 in the north of Scotland, but that he had observed it on Mugdock 

 Moor in mid-winter. Some of these birds remain the whole 

 year in districts in the south of Scotland, and they are not migra- 

 tory in England. A member stated that in Sutherlandshire they 

 are absent about three months in mid-winter. 



SPECIMENS EXHIBITED. 



By Mr. George Horn. — Carex ornithopoda, Wills, from Miller's 

 Dale, Derbyshire, a plant recently discovered in Britain. 



By Mr. Malcolm Black. — A collection of lichens which he had 

 brought from Canada. 



PAPER READ. 



Dr. Stirton, the President of the Society, then read a paper on 

 " Cosmopolitan Lichens." He said that lichens depended for their 

 support on the atmosphere and the moisture contained in it. 

 They will not flourish in an atmosphere in any degree vitiated, 

 and so they are a good test of the purity of the atmosphere of any 

 district. They are not to be found in fruit within a radius of six 

 miles from the centre of Glasgow. On the other hand, there is no 

 place in Scotland where they are found in greater abundance than 

 on Loch Tay side, and other facts tend to show that this district 

 is blessed with a pure and healthful atmosphere. But there are 

 some lichens which seem to flourish in a greater variety of condi- 

 tions than others, and these he called Cosmopolitan. He selected 

 as examples of these Urceolaria scruposa, Lecanora suhfusca, L. 

 atra, and Leptogium tremelloides, which are found in nearly every 

 climate, in a strange variety of positions, and at almost every alti- 

 tude. He also exhibited the Beindeer Moss, which is of universal 

 distribution. Lichens being so easily afiected by any change in 

 the atmosphere, it follows that during the long period in which 

 they have flovirished on the earth the atmosphere must have 

 remained practically unchanged in its constitution. He also 

 adverted to the genera Graphis and Arthonia, and described the 

 curious phenomena of their fructification. 



