^58 



ARGENTINA — CHILI 



coinnion with the Colombian sub-region, and Oxycliona (4 sp.) 

 with tlie Central American. Bulimvs has 

 in all 06 species, the sub-genera Pachyotus 

 (Fig. 233) and StropJiochilus being peculiar. 

 Bidimulus, thoiigh not so abundant as in Peru 

 and Ecuador, has about 60 species, of which 



Fig 235 — Bulimidiis A^f^r^'cw/^ (Fig. 235) is the most remarkable 

 {Xarioiiii) naricuia group. Mcf/aspira is peculiar. Orthalicus has 



Wagu., Brazil. t < ■ i -i /-n • /a \ i 



only 4 species, while lomigerus (4 sp.) and 

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

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

 2)hortcs, and Helicimi. 



In Argentina, which may probaljly rauk as a separate pro- 

 vince, the tropical forms greatly decrease, 

 Strejitaxis being reduced to 2 species, and 

 Buluiiii>< and Bidimulus together to 40, while 

 Ortludictis, the great Helices, and the land 

 operculates disappear altogether. Odonto- 

 stcniitis (Fig. 2.")G), a genus of the Pupidae, is 

 aljundant in the northern part of the province. 

 Two or three species of Clidina occur. 



(5) The Chilian Sub-region.^ — The greater 

 part of Chili, from its arid and rainless climate,is 

 unfavourable to the existence of land Mollusca. 

 Bidi}nus(Boriis)Hti\l has 3 or 4 species, and i>w//- 

 mnlus {Plcctodylus 11, Scutcdus 9, Peroiiaeiis 7) is fairly abundant, 

 but the profusion of the tropics is wanting. There are no car- 

 nivorous genera, and only two land operculates. A remarkal)le 

 form of Helix {Macrocyclis, Fig. 237) is quite peculiar, l)ut the 

 majority of the species belong to two rather oljscure groups, 

 Steimnwda and Amjdiidoxa. Chilina, a singularly solid form of 

 LimiKtea (of which 8 sp., with a sul)-genus PsrudocJi di no , occnr in 

 Chili), is peculiar to Chili, 8. Brazil, and I'atagonia. From the 

 two islands of Jna?!. Fernandez and Mandftiera, are known several 

 Helix, of Chilian affinity, several curious Suceinect, a Humalonyx, 

 Leptinaria, and JVothus, and three species of TonuUellina, with 

 the almost universal Limeix gagates. 



The question of the existence at some remote period of a 

 Xeantarctic continent, which formed a communication between 

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



Fig. 236. — Odcmto- 

 stomus iMiitagru- 

 elinus Moric, S. 

 Brazil. x i. 



