326 



POLYNESIA 



CHAP. 



affinity. Otoconcha is peculiar. The fresh-water Mollusca, 

 besides the Isidora characteristic of the sub-region, are partly 

 related to New Caledonia through the occurrence of Melanopsis^ 

 partly to Tasmania through Potamopyrgus^ while the peculiar 

 Latia is possibly akin to G-undlaehia (Tasmania). The land 

 operculates number only 5 genera and 14 species in all, excluding 

 a doubtful Diplommatina} 



Land and 



Fn 



ish-water Mol 



lusc 



a of the Neoz 



eala 



nian Provinc 



g 



Schizoglossa . 



1 



Gerontia . . 



. 2 



Placostylus . . 



1 



Melanopsis . . 



2 



Paryphanta 



5 



Allodiscus . 



. 10 



Carthaea 



1 



Potamopyrgus 





Rhytida . . . 



6 



Pyrrha , . 



. 1 



Tornatellina 



1 



Paxillus . . . 





Rhenea . . . 



2 



Therasia . . 



. 7 



Janella . . 



3 



Lagochilus . . 





Helicarion . . 



1 



Phenacohelix 



. 3 



Latia . . . 



^ 



Omphalotropis 





Otoconcha . . 



1 



Suteria . . 



. 1 



Ancylus . . . 



2 



Realia . . . 





Microcystis , . 



1 



riammulina 



. 13 



Limnaea . . . 



5 



Hydrocena . . 





Trocbonanina . 



1 



Laoma . . 



. 23 



Amphipeplea 



2 



Unio . . . . 



9 



Phacussa . . 



3 



Endodonta . 



. 10 



Planorbis . . 



1 



Sphaerium . . 



1 



Thalassohelix . 



5 



Charopa . . 



. 28 



Isidora . . . 



7 



Pisidium . . 



2 



Lord Howe's ±. is remarkable as containing a Placostylus^ 

 which thus links the island with this province. The remainder 

 of the fauna is Polynesian, with the exception of a species 

 (common to the Fijis) of Parmella, a slug akin to Helicarion, 

 Parmacochlea, and Cystopelta. & 



(3) The Polynesian Sub-region includes all the island groups I 

 of the central and southern Pacific (except those classified in the 

 Papuan and Australian sub-regions), from 

 the Pelews and Carolines in the west to 

 the Marquesas and Paumotus in the east, 

 and from the Tonga group in the south 

 to the Sandwich Is. in the north. It may 

 be subdivided into (a) the Polynesian pro- J 

 vince proper, and (5) the Hawaiian pro- 

 FiG. 216. — Characteristic vince, which includes the Sandwich Is. 



Polynesian Mollusca: A, ^vy^l-r;. 



(«) The general features of the Poly, 

 nesian province are very similar through- 

 out, although the Mollusca of each island 

 group are in the main peculiar. The species are mostly small 



1 Hedley and Siiter, Proc. Linn. Soc. N. S. Wales (2), vli. p. 613. Twenty- 

 one species are "introduced." 



Achatinella vulpina Fer., 

 Sandwich Is. ; B, Par- 

 tula planilabrum Pease, 

 Society Is. 



