5 8 PREHISTORIC E UR OPE. 



2. Species which have retired from the district, but are still 



natives of France. 



3. Species which do not now occur in France, but are living 



in other parts of Europe. 



4. Species which are extinct or entirely exotic. 



The great majority of the shells belong to the first group, the 

 most common and most characteristic by reason of its abundance 

 being Helix arbustorum. Group 2 is represented by Helix 

 limbata, which is common in the lower Pyrenean region, and in 

 the south-west of France, but much rarer in the region of the 

 Loire and Normandy. It has not been cited as occurring in the 

 neighbourhood of Paris. Another migrated species is Bulimus 

 montanus, which has retired to the hillier parts of France ; it is 

 found also in the Jura, the Alps, and the Pyrenees. Clausilia 

 dubia has a similar distribution ; Pomatias septemsjoirale has not 

 been met with in the region round La Celle ; it occurs, however, 

 in the valley of the Oise, etc., and is common in all the hilly 

 regions of the east. It is noteworthy, says M. Tournouer, that 

 these three last -mentioned species have their present head- 

 quarters rather towards the east, and outside of France than in 

 France itself. Under the third group comes Helix bidens, a 

 form which is no longer met with in Western Europe. It has 

 been cited as occurring in the Alps, but M. Tournouer thinks 

 this determination is more than doubtful. It is widely dis- 

 tributed in Eastern and North-eastern Europe, from Croatia, 

 Hungary, and Transylvania to Sweden and Russia. One of the 

 most remarkable forms of the fourth group is the large zonites 

 (Zonites acieformis). This shell belongs to a group which is 

 foreign to Northern France and similar latitudes in Europe, and 

 is no longer represented in the western regions of our continent. 

 The forms to which it most nearly approaches (Zonites verticillus, 

 Fer., and Z. croaticus, Partsch) are natives, the one of Austrian 

 Tyrol, from which it extends into Bavaria, and the other of 

 Croatia. Other extinct species are Succinea joinvillensis, Helix 

 chouquetiana, H. Radigueli, Cyclostoma lutetiana, etc. 

 ' The inferences drawn by M. Tournouer as to the climatic 



