NATURAL HISTORY SOCIETY OF GLASGOW. 131 



tainecl by Mr James Dairon from a thick bed of brick clay- 

 recently cut through in St Enoch's Square. He remarked that 

 this discovery, along with facts recently observed, proves clearly 

 that the Eiver Clyde down to the period of the deposition of our 

 brick clays, must have been an arm of the sea at Glasgow, and of 

 considerable width, as these recent marine shells indicated, 

 possibly receiving (according to Mr Robert Chambers) the waters 

 of the river not lower down than Bothwell Bridge. 



PAPERS READ. 



I. — On some facts in the Physical Geogmi^hj of British Plants, and 

 their Geological Interpretation; with sjMcial reference to recent 

 Botanical and Geological Investigations in Scotland. By Mr 

 John Shaw. 

 He stated that although the flora of the British Islands did not 

 rank as a separate botanical province, it was an extremely inter- 

 esting one in its past history and general character. Europe was 

 divided into three botanical zones:— Zonse septentrionalis, inter- 

 media, and meridionalis; Britain had plants belonging to all three. 

 He pointed out the mistake Edward Forbes had been led to 

 commit when he divided the south of Britain and Ireland into 

 three assemblages of plants, viz.: in Kent, in the south-west of 

 England and south-east of Ireland, and the south-west of Ireland. 

 Although the last named had some more southerly and delicate 

 forms than the others, their existence was probably owing to its 

 very mild climate. The isotherm of 41° Fahr. in the month of 

 January passes through the south-west of Ireland and south of 

 France, Italy, and Greece. Mr Shaw therefore believed that all 

 the southern forms found m the whole south of Britain, and in 

 stray nooks throughout England, Scotland, and Ireland, came into 

 the country at one period, and that they were all wanderers from 

 the Mediterranean shores. The author then mentioned some 

 particulars of the intermediate or German flora, and entered fully 

 into the Alpine and Arctic floras of Great Britain. He showed 

 that the latter were necessarily, from the lowness of our moun- 

 tains, and the influence of the Gulf Stream, not fully represented. 

 By far the most interesting feature, however, in the flora of 

 Britain was the number of species it embraced in common with 

 North America. The floras of Europe and America have a con- 

 spicuous community of species, but it was a noticeable fact that 



