(_a_) _The Papuan Province._--The molluscan fauna of New Guinea is the richest and by far the most original of all the Australasian region. We find ourselves, almost in a moment, in a district full of new and peculiar forms. New Guinea may be regarded as the metropolis of the rich Helicidan fauna, which is also characteristic of the Moluccas to the west, of N. and N.E. Australia to the south and south-east, and of the Solomons and other groups to the north-east. Here abound species of _Papuina_ and _Insularia_ (the latter being quite peculiar), among which are found, if not the largest, certainly the most finished forms of all existing _Helices_. _Chloritis_ (13 sp.), _Planispira_ (5), and _Cristigibba_ (9) are common with the Moluccas, while a tropical Australian element is shown in _Pedinogyra_ (1) and _Hadra_ (4). Very remarkable, too, is the occurrence of one species of _Obbina_ and _Rhysota_, genera which culminate in the Philippines and here find their most eastward extension; while a single _Corasia_ serves to form a link between the _Corasia_ of the Philippines and those of the Solomon Is., if the latter are true _Corasia_. We naturally find considerable traces of a Polynesian element, which appears to be principally characteristic of the eastern part of the island. Most noteworthy in this respect is the occurrence of _Partula_ (3), _Tornatellina_ (1), _Charopa_ (1), _Thalassia_ (3). As compared with the true _Pulmonata_, the operculates are feebly represented, and the great majority are of a markedly Polynesian type. Not a single _Cyclophorus_ occurs; _Lagochilus_, _Alycaeus_, and all the tubed operculates, so marked a feature of the Indo-Malay fauna, are conspicuous by their absence, and the prevailing genera are _Cyclotus_, _Helicina_, and a number of sections of _Pupina_. _Leptopoma_, as in the Philippines, is strongly represented. Not that an Indo-Malay element is altogether absent. We still have _Xesta_ (5), _Hemiplecta_ (8), and even _Sitala_ (2), but the great predominance of _Helix_ seems to have barred the progress, for the greater part, of the Indian Naninidae. The slugs appear to be represented by a solitary _Vaginula_. A single _Perrieria_ is a very marked feature of union with Queensland, where the only other existing species (_P. australis_) occurs. The solitary _Rhytida_, so far the only representative of the carnivorous group of snails, emphasises this union still further. Little is known of the fresh-water fauna. _Melania_ (28 sp.) is predominant, but on the whole the relations are Australian rather than Indo-Malay. _Ampullaria_ is wanting, while a decisive point of similarity is the occurrence of _Isidora_ (3 sp.), a genus entirely strange to the Oriental region, but markedly characteristic of the Australasian. _Land and Fresh-water Mollusca of New Guinea_