_Lord Howe’s I._ 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 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 province proper, and (_b_) the Hawaiian province, which includes the Sandwich Is. only. [Illustration: FIG. 216.--Characteristic Polynesian Mollusca: =A=, _Achatinella vulpina_ Fér., Sandwich Is.; =B=, _Partula planilabrum_ Pease, Society Is.] (_a_) The general features of the _Polynesian province_ are very similar throughout, although the Mollusca of each island group are in the main peculiar. The species are mostly small and obscure. _Helix_ scarcely occurs, its place being taken by small Zonitidae (_Microcystis_, _Charopa_, _Trochomorpha_, etc.), and by groups of so-called _Patula_ (_Endodonta_, _Pitys_, etc.), the exact position of which is not yet settled. _Libera_, remarkable for its method of ovipositing (p. 128), is peculiar to the Society and Hervey Is.; _Partula_ is almost universal, attaining its maximum (40 sp.) in the Society Is.; _Tornatellina_, _Pupa_, and _Vertigo_ occur throughout. The land operculates consist chiefly of _Omphalotropis_, _Pupina_, _Realia_, and _Helicina_. _Diplommatina_ and _Palaina_ are abundant on the Pelews, and a _Moussonia_ occurs in the Samoa Is. _Ostodes_, a small form of _Cyclophorus_, is found in some of the southern groups. The fresh-water operculates are _Melania_, _Neritina_ (including _Clithon_, a sub-genus furnished with spines), and _Navicella_; there are no Unionidae, while fresh-water _Pulmonata_ are very scarce. (_b_) The land Mollusca of the _Hawaiian province_ are distinguished by the possession of four entirely peculiar genera--_Achatinella_, _Leptachatina_, _Carelia_, and _Auriculella_. More than 300 of the two former genera have been described, every mountain valley of some of the islands having its own peculiar species. The destruction of the indigenous herbage by goats is rapidly extinguishing many forms. _Partula_, and the small land operculates, so characteristic of the other groups, are, with the exception of _Helicina_, entirely wanting. The occurrence of one of the _Merope_ group of _Helix_ (Solomon Is.) is remarkable, and there is a rich development of _Succinea_. “_Patula_,” _Microcystis_, _Tornatellina_, and the other small Polynesian land _Pulmonata_ are well represented. The presence of _Isidora_, absent from the central Pacific groups, is remarkable, and _Erinna_ is a peculiar genus belonging to the Limnaeidae.