The fresh-water Mollusca of Madagascar contain further traces of Indian relationship. Thus we find two species of _Paludomus_, a genus whose metropolis is Ceylon, India, and Further India, and which is barely represented on the Seychelles and in the Somali district. _Melanatria_, which is peculiar to Madagascar, has its nearest affinities in the Cingalese and East Indian faunas. Several of the _Melania_ and the two _Bithynia_ are of a type entirely wanting in Africa, but common in the Indo-Malay sub-region. Not a single one of the characteristic African fresh-water bivalves (_Mutela_, _Spatha_, _Aetheria_, _Galatea_, etc.) has been found in Madagascar. On the other hand, certain African Gasteropoda, such as _Cleopatra_ and _Isidora_, occur, indicating, in common with the land Mollusca, that an ultimate land connexion with Africa must have taken place, but at an immeasurably remote period. _Land and Fresh-water Mollusca of Madagascar_ Ennea 9 Urocyclus 2 Helicarion (?) 1 Macrocyclis (?) 1 Kaliella 1 Nanina (inc. sed.) 9 Ampelita 35 Helicophanta 17 Pachnodus 2 Rachis 2 Leucotaenia 2 Clavator 2 Achatina 3 Opeas 2 Subulina 3 Vaginula 4 Limnea 2 Planorbis 3 Isidora 3 Melania 7 Melanatria 4 Paludomus 2 Vivipara 1 Bithynia 2 Cleopatra 2 Ampullaria 6 Cyclophorus 2 Cyclotus (?) 1 Cyclostoma 54 Otopoma 5 Lithidion 1 Acroptychia 3 Hainesia 3 Unio 1 Corbicula 2 Sphaerium 1 Pisidium 1 _The Comoro Islands._--This isolated group possesses about 100 species, almost all of which are peculiar. The principal feature is the rich development of _Ennea_ (30 sp.). On the whole the group shows more relationship to Madagascar than to the mainland. Thus we have six species of true _Cyclostoma_, and only one _Achatina_, while among the fresh-water genera is _Septaria_, which is characteristic of the whole Malagasy Sub-region, but is absent from the mainland. The Helicidae are all of insignificant size. Peculiar to the group is the remarkable genus _Cyclosurus_ (Fig. 152, p. 247). (_b_) _The Mascarene Province_ (Mauritius, Bourbon, Rodriguez, and the Seychelles).--The percentage of peculiar species, which is very high, can only be paralleled in the case of some of the West Indian islands, and sufficiently attests the extreme isolation of the group from Madagascar. We have--