76 TRANSACTIONS OF THE 



second leaf-bed ; 5th, a second bed of volcanic ash ; 6th, a bed of 

 shale or consolidated mud with few leaf impressions ; 7th, a seam 

 of dark amorphous basalt ; 8th, a base of columnar basalt. 



As to the oiigin of these beds. Dr. Mathie thought that the 

 theory advanced by the Duke of Argyll was the correct one. 

 In a paper read before the Geological Society the Duke of Argyll 

 said that alternations of quiet autumnal sheddings of leaves into 

 the smooth, still waters of a shallow lake, with periods of volcanic 

 eruption and activity, are the most probable causes of the Ardtun 

 beds. Autumn after autumn the leaves are accumulated, till a 

 period of volcanic eruption arrived when a stream of liquid mud 

 was poured over them, insinuating itself between the upper and 

 looser layers of the leaf-bed ; upon this a strata of other volcanic 

 matter was deposited ; and thereafter came a period of rest and 

 deposition of leaves, which in turn was followed by another 

 volcanic eruption. He concluded by a description of the chief 

 vegetable remains found in the beds. 



The paper was illustrated by diagrams showing the geological 

 arrangement of the beds, and by numerous specimens. 



18th December, 1874. 

 Mr. Eichard M'Kay, Vice-President, in the chair. 



PAPER READ, 



Mr. Stuart M 'Donald x'ead a paper on the common gnat, in 

 which he gave some interesting details of the development and life 

 history of this insect. 



An interesting discussion followed, in which some account of 

 the flight of insects was given by several members. 



8th January, 1875. 



Mr. Kichard M'Kay, Vice-President, in the chaii\ 



Mr. "W. C. Crawford, Kelvinside Terrace, was elected a resident 



member, and Mr. James G. Scott, Rangoon, as a corresponding 



member. 



SPECIMENS EXHIBITED, 



By Mr. Allan. — An interesting series of mosses from Devon. 



