358 ARGENTINA — CHILI 



jphia are common with the Colombian Sub-region, and Oxychona 

 (4 sp.) with the Central American. Bulimus 

 has in all 36 species, the sub-genera Pachyo- 

 tus (Fig. 233) and Strophochilus being pecul- 

 iar. Bulimulus, though not so abundant as 

 in Peru and Ecuador, has about 60 species, of 



Fig. 235. — Buiimuius which Navicula (Fig. 235) is the most remark- 



mTn.'^BrizT''''^'' able group. Megaspira is peculiar. Orthali- 



eus has only 4 species, while Tomigerus (4 sp.) 



and Anostoma (3 sp.) are common with Venezuela. Land opercu- 



lates are scarce, and appear to include only NeocydotuSy Cyclo- 



phorus, and Helieina. 



In Argentina, which may probably rank as a separate pro- 

 vince, the tropical forms greatly decrease, 



Streptaxis being reduced to 2 species, and 



Bulimus and Buiimuius together to 40, while 



OrthalicuSy the great Helices, and the land 



operculates disappear altogether. Odonto- 



stomus (Fig. 236), a genus of the Pupidae, is 



abundant in the northern part of the province. 



Two or three species of Chilina occur. 



(5) The Chilian Sub-region. -The greater ^^^ ^7- odonto- 



part of Chili, from its arid and rainless climate, stomus pantagru- 



is unfavourable to the existence of land Mol- !f^^^.? ^?^^^" ^^ 



Brazil, x^. 



lusca. Bulimus (Boms') still has 3 or 4 species, 

 and Buiimuius (^Plectostylus 11, Scutalus 9, Peronaeus 7) is 

 fairly abundant, but the profusion of the tropics is wanting. 

 There are no carnivorous genera, and only two land operculates. 

 A remarkable form of Helix (^Macrocyclis^ Fig. 237) is quite 

 peculiar, but the majority of the species belong to two rather 

 obscure groups, Stepsanoda and AmpTiidoxa. Chilina^ a singu- 

 larly solid form of Limnaea (of which 8 sp., with a sub-genus i 

 Pseudochilina^ occur in Chili), is peculiar to Chili, S. Brazil, f 

 and Patagonia. From the two islands of Juan Fernandez and 

 Masafuera^ are known several Helix^ of Chilian affinity, several 

 curious Succinea^ a Homalonyx^ Leptinaria^ and Nothus^ and three 

 species of Tornatellina, with the almost universal Limax gagates. 

 The question of the existence at some remote period of a 

 Neantarctic continent, which formed a communication between 

 the three great southern peninsulas of the world, is one on 



