THE DISTRICT OF SCHEMNITZ, HUNGARY. 325 



spects with Mr. Judd's ; but Mr. Judd had greatly simplified our 

 notions of what had hitherto appeared to be an excessively complex 

 district. 



Mr. Judd, in reply, stated that marine shells had been found 

 along with the plant-remains in the beds associated with andesitic 

 lavas, and these had borne out the views held by botanists with 

 regard to the age of these lavas. The Duke of Argyll's discovery of 

 the leaf-bed in the Isle of Mull constituted the starting-point for all 

 our knowledge of the age of the volcanic rocks of the Western Isles. 

 The transition of granite into the volcanic rocks was very marked 

 in that island. The difference between the rocks with glassy plagi- 

 oclase and the earthy rocks in the Schemnitz district was possibly 

 connected with the presence or absence of metallic deposits. In 

 Scotland the rocks were destitute of ores ; but in Hungary they had 

 evidently been subjected to the action of acid gases, and valuable 

 metalliferous minerals are found abundantlv in them. 



