PEARCE : MOLLUSCA OF EAST SWITZERLAND. 211 



From the Maloja Pass, which represents a sudden fall in 

 elevation of not much less than looo feet, the Val Bregaglia is 

 a continual descent southwards into Italy. Promontogno, 

 about nine miles from the pass, the southernmost village I 

 reached in this valley, is only 2,687 feet above the sea. It is 

 at this place that the Alpine pines, larches, &c., suddenly yield 

 to the chesnuts and walnuts of a more southern vegetation. 



The rocks of these valleys are chiefly of crystalline lime- 

 stone, gneiss, and mica-schist. Granite (or a granite-like rock), 

 occurs at various points in the Engadine Valley. The altitudes 

 given in the following notes are taken from Baedeker's " Switzer- 

 land" (nth edition). 



All the species enumerated in this paper, excepting three 

 slugs — the names of which have been bracketed in the list — have 

 been examined by Mr. Roebuck and Mr. Taylor, of Leeds. My 

 best thanks are due to them for having so kindly identified the 

 more doubtful forms, as well as for favouring me with their 

 notes on most of the species. 

 Pisidium fontinale Drap. — Shallow ditches at Isola, Upper 



Engadine. 

 P. pusillum Gmelin. — Plentiful in the shallow pools and 



ditches by the Engadine lakes; also in a ditch above Maloja, 



near a farm, at the height of about 6,500 ft. I did not take 



this and the preceding species together. 

 Planorbis spirorbis Miiller. — Not uncommon in the Upper 



Engadine, in shallow sluggish water at Sils Maria, Baseglia, 



Isola, Maloja and Silvaplana. 

 LImnaea peregra Miiller. — Abundant in the shallower waters 



of the Upper Engadine ; and also in the Bergel Valley. 



Not taken in the deeper water of the lakes proper. While 



varying considerably in form and size, the shells as a rule, 



are solid looking, dark in colour, and often much eroded. 



The following seem the chief variations : — 



(a). The type from both the Engadine and Bergel 



valleys. 



