The _Louisiades_, the _d’Entrecasteaux_, and _Trobriand Is._, and _Woodlark I._, are closely related to New Guinea, containing no peculiar genera. Each group, however, contains a considerable proportion of peculiar species, an indication that their separation from New Guinea dates from a very distant period. From the Louisiades are known 34 species in all, 22 of which are peculiar. The fauna of the _Admiralty Is._, of _New Hanover_, and _New Ireland_ is markedly Papuan, without any especial feature of distinction. The Admiralty Is. contain 15 sp. _Papuina_, 7 _Chloritis_, 1 _Planispira_, and 1 _Corasia_. A single _Janella_ shows relationship with the New Hebrides and with New Zealand. In New Ireland _Planispira_ (which is specially characteristic of W. New Guinea and the Moluccas) has disappeared, but there are 7 _Papuina_ and 6 _Chloritis_. The essentially Polynesian _Partula_ is present in both groups. The prominent feature of the Mollusca of the _Solomon Is._ is the extraordinary development of _Papuina_, which here culminates in a profusion of species and singularity of form. The genus is arboreal, crawling on the branches and attaching itself to the leaves of trees and underwood. Of the 140 land _Pulmonata_ known from the group, no less than 50, or 36 per cent, are _Papuina_. Ten species of _Corasia_ occur, but whether the shells so identified are generically identical with those of the Philippines, is not satisfactorily determined. _Trochomorpha_, with 22 species, here attains its maximum. _Chloritis_ begins to fail, but still has 3 species. Indo-Malay influence still appears, though feebly, in _Hemiplecta_ (3), _Xesta_ (1), and possibly even _Macrochlamys_ (1). The _Rhytida_, the 3 _Hadra_, and possibly the _Paryphanta_ represent the Australian element. The growing numbers of _Partula_ (13), the small and inconspicuous land operculates (only 22 in all, with _Helicina_ very prominent), and the almost complete absence of fresh-water bivalves, show signs of strong Polynesian affinities. An especial link with the New Hebrides, New Caledonia, and the Viti Is. is the occurrence of _Placostylus_ (16 sp.). It is very remarkable that this genus should occur in the Solomon Is. and not in New Ireland. The occurrence of _Streptaxis_, if authentic, is very noteworthy, the nearest species being from the Philippines. _Land and Fresh-water Mollusca of the Solomon Islands_