55 



remarkable features of Fingal's cave, and the craigs of Edinburgli, and 

 Stirling, which he termed fossil volcanoes of our own country, and the 

 fissure flows, dykes, and prismatic traps of the West of Scotland, and 

 North of England. The probable cause of volcanic action, is the 

 association and dissociation taking place among the elements of the 

 earth's interior, the conditions of which are similar to those now pre- 

 vailing in the sun, but in a reduced stage of energy. The author 

 concluded by remarking that the fair county of Kent was possibly 

 preserved by Hecla on the north and Vesuvius on the south, acting 

 as safety valves, by permitting immense volumes of steam to escape. 

 This outpouring of watery vapour is the chief cause of the shrinkage 

 and folding of the earth's crust, and of the great features of the globe. 



An additional interest vras given to this paper by an account of 

 some personal experiences on the cone of Vesuvius and remarks on 

 the flow of lava streams. 



The papers were made attractive by numerous illustrative sketches 

 and wall diagrams from the facile pencil of Mrs. McDakin. 



XVI. 



THE HERRING GULL. fLarus Argentatus.J 

 Abstract of Paper 



BY 



MR. GEORGE GRAY. 



Read before the Dover Field Club, 17th March, 1891. 



The Herring Gull is the most widely distributed member of its 

 family on the coasts of the Eritish islands ; breeding wherever 

 precipitous clifl's, or isolated stacks of rocks afford suitable situations. 

 It is not confined to our shores, however, but is abundant on the coasts 

 of Scandinavia and the Baltic, whilst immense numbers occupy the low 

 Frisian islands, especially Sylt, whence from forty thousand to fifty 

 thousand eggs are taken for eating in a season. Southwards it ranges 

 down the western seaboard of Europe, as far as the Azores. In the 

 Mediteri'anean there is a resident sub-species {Larus caehinans, of Pallas) 

 characterized by a darker mantle, lemon yellow legs and feet, and an 

 orbital ring of a deep orange red. This form not only extends to the 

 Black and Caspian Seas, but reaches northwards to Archangel, and still 

 further eastward it frequents the shores of the Pacific. 



But although of so wide a range, we may yet consider the Herring 

 Gull as truly a Dover bird, for it is with us all the year round, and even 



