Mr. J. G. Jeffreys's Notes on Swiss Mollusca, 21 



limestone. But the difference of form is chiefly perceptible on 

 the Alps and in the Alpine valleys, where the sister kingdoms 

 of Botany and Entomology also hold their courts and delight 

 the naturalist. Some species are only found on the confines of 

 Italy, although in a subalpine zone, and appear to depend on 

 latitude rather than on climate or temperature. One species 

 [Helix sylvatica) is found as well on the plains of the Rhone 

 Valley, as (though dwarfed in size) at a height of many thou- 

 sand feet above the level of the sea. The shores of Lake Leman 

 offered the lowest elevation above that level, being, according to 

 Keller's map, 1150 feet; and the highest point at which I 

 found living MoUusca was the Ryfel, about 8000 feet (near 

 Monte Bosa, in the Haut Valais), where Vitrina diaphana, var. 

 ( V. glacialis of Forbes) occurs in ground which is almost con- 

 stantly frozen. How far specific variation may be influenced by 

 climate, temperature, or latitude, is a difficult problem, which 

 requires for its solution far more materials and data than we as 

 yet possess. 



I will now plunge in medias res, adopting Charpentier's Cata- 

 logue as my text-book. 



Vitrina diaphana, Draparnaud. 



Rochers Naye and Dent de Jaman ; Mont Tendre, on the Jura ; 

 Zermatt ; Le Saleve, near Geneva. Not uncommon. 



Var. a. Spira utrinque compressa. Animal nigro-fuscum. 



Vitrina glacialis, Forbes " On Alpine Testacea,'' in Magazine of 

 Zoology and Botany, vol. i. 



Le Ryfel, near Monte Rosa, in the Haut Valais, at an elevation of 

 about 8000 feet above the sea. 



My late lamented friend. Professor Edward Forbes, con- 

 sidered this to be a distinct species, because of the darker colour 

 of the animal ; but the gradations of colour and form from this 

 variety to the next through the typical species, are almost im- 

 perceptible. 



Var. /3. Spira superne prominula. Vitrina nivalis, Charp. 

 Alps near Bex (Charp.) ; — Valley of St. Nicholas. Rare. 



Vitrina pellucida, Miiller. 



Rochers Naye; Chable; Belmont and Les Pierrettes, near Lausanne; 

 Devens. Common. 



Vitrina annularis, (Venetz), Ferussac. F. subglohosa, Michaud 

 and Morelet. 

 Devens ; Sion ; Foully (Charp.) ;— Valley of St. Nicholas ; St. 

 Maurice ; Chable in the Vallee de Bagnes. Rare. 



