114 MANUAL OE THE MOLLTJSCA. 



the clouds discharge themselves on the east side of the Andes, 

 and rain is so rare on the west coast that in some parts it only 

 falls two or three times in a century. In Peru, during great 

 part of the year, a vapour rises in the morning, called, the 

 "garua; " it disappears soon after midday, and is followed by 

 heavy dews at night. 



Mr. Cuming collected 46 species of land snails in Peru ; and 

 Dr. Pfeiffer enumerates 100, but perhaps half the latter were 

 from the eastern side of the Andes, belonging to the Brazilian 

 Province. They are mostly Bulimi, and are smaller and less 

 richly coloured than those of Bolivia and Brazil ; B. Benickei, 

 solutus, and turritus are peculiar forms. Cistula Delatreana is 

 the only operculated land snail, and Vaginulus limayamis the 

 only slug. 



Helix 12 Pupa 1 Ancylus 1 



Bulimus 79 Balea 1 AmpuUaria 1 



Succinea 5 Cistula 1 Paludestrina 2 



Grlandina 1 Physa 1 Cyrena 3 



Tomatellina 1 Planorbis 3 Anodon 1 



25. Argentine Eegion. 



The " region of arborescent Compositse" has afforded scarcely 

 any land snails ; only 7 species of Bulimus, and 3 Helices are 

 recorded, but some others may have been included with those 

 of Brazil and Ghili. From Bolivia this province is separated 

 by the wide plains of the Great Desert, or northern prolonga- 

 tion of the Pampas ; and all the eastern part has been submerged 

 at a recent (geological) period; so that the only promising 

 districts are Paraguay and the eastern declivities of the Chilian 

 Andes. The fresh-water shells of the La Plata and its tribu- 

 taries are more remarkable. 



Chilinia..... 7 Cyclas X Byssoanodon 1 



Planorbis 11 Pisidium X Monocondylsea 6 



Ancylus 4 Corbicula ..,,. 2 Mycetopus X 



AmpuUaria 7 Unio 7 Castalia X 



Asolene 1 Anodon 10 Iridina 1 



Paludestrina 7 



AmpuUaria (Marisa) cornu-arietis is a characteristic shell; 

 Paludestrina lapidum has a claw-like (non-spiral) operculum, 

 and appears to belong to the Melaniadce. 



26. Chilian Eegion. 



The northern part of Chili belongs to the same physical region 

 with Peru, consisting of dry and rainless plains. Here the land 



