Vol. 62.] TARNS OF THE CANTON TICINO. 193 



Plate XVIII. 

 Contoured map of Lago Cadagno, on the scale of 5000 : 1 . 



Plate XIX. 

 Contoured map of Lago Scuro, on the scale of 5000 : 1. 



Plate XX. 



Contoured map of Lago Taneda, on the scale of 5000 : 1. For ' Lizera* read 

 1 Lisera.' 



Plate XXI. 

 Contoured map of Lago di Lucendro, on the scale of 5000 : 1. 



Discussion. 



The President observed that he would have liked to say much 

 which, on account of the lateness of the hour, he must omit. He 

 thought that the case of the deep lakelet Scuro and its companion, 

 situated close below the watershed, was a hard nut for advocates 

 of glacial erosion of such lakes to crack. He could not sit down 

 without referring to the amount of labour devoted by the Author, 

 not only to the study of the lakes, but also to the preparation of 

 his paper for presentation to the Society. 



Prof. Bonney heartily concurred with the President's remarks 

 on the thoroughness with which the Author had worked out his 

 subject and the clearness of his exposition. He should like to 

 state, for the information of the Fellows, that, in those lakes 

 which he had described in the ' Geological Magazine,' he had not 

 admitted that ice could have done more than form the rock-basin 

 now filled with water. He had supposed, for instance, at the Lago 

 di Tremorgio, that first a corrie was formed in the usual way by 

 streams, and then, when the ice advanced, the descending mass might 

 have a scooping effect, at the foot of so deep a slope. In regard 

 to .Lake Bitom, he felt doubts as to whether the headlands on the 

 south side could be due to flexures, for these would correspond with 

 the north-north-east to south-south-west folding, which he thought 

 was on a large scale and was older than the east-to-west folding ; 

 he doubted also whether the nipped-up east-to-west strips of rauch- 

 wacke were sufficiently large to cause, when dissolved, so complete a 

 removal of the intervening wedges of much less soluble rock. The 

 idea of reversal in the Piora-Valley drainage presented difficulties 

 to him. If the water escaped eastward (supposing the floor to be 

 nearly at its present level), it would have to go over a pass now at 

 least 1200 feet above the lake. He thought also that the deepening 

 of the main valleys, to which the ' hanging valleys ' were due, had 

 been pre-Glacial, and that probably this part of the Val Bedretto 

 would have been under ice. even in inter-Glacial times. But, while 

 reserving judgment on these points until he had read the paper, he 

 was none the less sensible of its value. 



Dr. Johnston-Lavis asked the Author whether he had seen any 

 signs of carbonic-acid springs in the sites of these curious lakes. 



