FRESHWATER SHELLS. O 



Besides the Neritina fluviatilis, four species of Neritina now 

 extinct lived in the fresh waters of Switzerland. These are N. 

 picta, Fer., N. Grateloupana, Fer., N. Lintha, May., and N. 

 Heerii, May. One little species of Valvata (V. multiformis) 

 occurs in the third stage, and a Paludina (P. acuta, Drap.) in 

 the fourth and fifth stages ; the latter occurs in some places by 

 thousands. Of Melanopsis there are three species in the Swiss 

 collections, one of which (M. Kleinii, Kurr.) sometimes occurs 

 in great quantities ; it is nearly allied to a species of the Medi- 

 terranean zone (M. pr&rosa, Linn.). 



To these genera, which belong to the European fauna, the 

 Swiss have to add Melania as a striking exotic form. One spe- 

 cies (M. Escheri, Br., fig. 197) was discovered many years ago 

 at Kapfnach by Escher de la Linth,; and it has now been dis- 

 covered in almost all the Miocene formations of Europe. It 

 appears even as early as the Upper Eocene (in the Bartonian 

 stage of the Ralligstock), and may be traced thence up to the 

 CEningian stage. It seems to have had its centre of origin in 

 Switzerland, and to have first spread towards Eastern Europe 

 during the Upper Miocene period. Its nearest living allies 

 (Melania varicosa, Trosch., and M. pulchra, Busch) inhabit the 

 rivers of tropical Asia. 



2. ARTICULATA. 



a. Crustacea. 



The Crustacea are chiefly inhabitants of the sea ; but a few 

 representatives of most of the families which live in fresh water 

 or on land occur in the Swiss Miocene. 



Of the Isopods there is at CEningen a species of woodlouse 

 (Armadillo], one of those which, when in danger, draw in their 

 legs and roll themselves up like a hedgehog. The CEningian 

 species (Armadillo molassicus, Heer) retained this spherical form 

 even in death, as shown by the animal represented in fig. 210, 

 which closely resembles the common Armadillo. 



Of the little Ostracodes the carapaces are very common, of 

 which we find great masses of a species which was very widely 

 distributed in Miocene times (Cypris faba, Desm,, fig. 205) in 



