_The Canaries_ have about 160 species, only about a dozen of which are not peculiar. As many as 75 of these belong to _Helix_ (the sub-genera being very much the same as in the Madeiran group), and 11 to _Patula_. There is 1 species of _Parmacella_ (which occurs in this group alone), and 6 of _Vitrina_, of considerable size. A remarkable slug (_Plectrophorus_) was described from Teneriffe by Férussac many years ago, but it has never been rediscovered, and is probably mythical, or wrongly assigned. _Buliminus_ (_Napaeus_) has as many as 28 species, all but one being peculiar, and _Ferussacia_ 7. _Cyclostoma_ has two indigenous species, which, with one _Hydrocena_ and one _Craspedopoma_, make up the operculate land fauna. _The Azores_ are comparatively poor in Mollusca, having only 52 species, nearly two-thirds of which are peculiar. _Helix_ has 15 species, _Patula_ 4, and _Pupa_ 8. _Ferussacia_, so abundant in Madeira and the Canaries, is entirely absent, its place being taken by _Napaeus_ (7 sp.), which is curiously absent from Madeira, but richly represented in the Canaries. There are 7 _Vitrina_, while the land operculates consist of one each of _Craspedopoma_ and _Hydrocena_. A singular slug (_Plutonia_), with an ancyliform internal shell, is said to occur. The group was long believed to possess no fresh-water Mollusca, but two species (one each of _Pisidium_ and _Physa_) have recently been discovered. _The Cape Verdes_, owing to the extreme dryness of their climate, are poor in land Mollusca. There are 11 _Helix_, nearly all of which belong to the group _Leptaxis_, which is common to Madeira and the Canaries. _Ferussacia_ is absent, _Buliminus_ is represented by a single species, and there are no land operculates. Ethiopian influence, however, as might be expected from the situation of the group, is seen in the occurrence of an _Ennea_, a _Melania_, and an _Isidora_. It will be noticed how little countenance the molluscan fauna of these island groups gives to any theory of an Atlantis, any theory which regards the islands as the remains of a western continent now sunk beneath the ocean. Had ‘Atlantis’ ever existed, we should have expected to find a considerable proportion of the Mollusca common to all the groups, and perhaps to Europe as well, and there would apparently be no reason why a genus which occurred in one group should not occur in all. As a fact, we find the species extremely localised throughout, and genera occur and fail to occur in a particular group without any obvious reason. All the evidence tends to show that the islands are purely oceanic, and have been colonised from the western coasts of the Mediterranean, _i.e._ from the direction of the prevailing currents and winds.