Fig. 223.—Helix (Helicophanta) Souverbiana Fisch., Madagascar, showing embryonic shell. × ⅔.
Fig. 224.—Cyclostoma campanulatum Pfr., Madagascar.
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—
| Total sp. | Land sp. | Fresh-water sp. | Peculiar | Peculiar to group | |
| Mauritius | 113 | 104 | 9 | 78 | 102 (90 p.c.) |
| Bourbon | 45 | 40 | 5 | 19 | 38 (84 p.c.) |
| Rodriguez | 23 | 19 | 4 | 15 | 21 (95 p.c.) |
| Seychelles | 34 | 27 | 7 | 24 | 30 (90 p.c.) |
The Mollusca of the group exhibit three distinct elements, the Indigenous, the Madagascan, and the Indian and Australasian.