Fig. 219.—Tiphobia Horei E. A. Smith, L. Tanganyika.
Fig. 220.—Mollusca characteristic of L. Tanganyika: A, Nassopsis nassa Woodw.; B, Spekia zonata Woodw.; C, Syrnolopsis lacustris E. A. Smith.
Fig. 221.—Achatina zebra Lam., S. Africa. × ½.
(2) The South African Sub-region.—The principal characteristic of the Mollusca of S. Africa is the occurrence of numerous small species of Helicidae, belonging chiefly to the groups Pella, Phasis, Dorcasia, and Sculptaria, all of which are practically peculiar. Carnivorous genera are also prominent, Ennea here attaining its maximum. Rhytida (to which several species still regarded as Pella belong) is common only to the S. Pacific and Australasia, and forms, with Isidora among the fresh-water pulmonates, a remarkable link of connexion. Aerope, the largest of all helicoid carnivorous genera, and Chlamydephorus, a carnivorous slug with an internal shell, are peculiar. Achatina is still abundant, but Limicolaria is wanting. Livinhacea, a form with a continuous peristome, perhaps akin to Bulimus; Apera, a form of slug; and Coeliaxis, a genus perhaps akin to the Papuan and Queensland Perrieria, are all peculiar. The land operculates, which are not numerous, are of the East African type.
Land Mollusca of the S. African Sub-region
| Chlamydephorus | 1 |
| Ennea | 31 |
| Aerope | 5 |
| Rhytida | 3 |
| Helicarion | 3 |
| Trochonanina | 1 |
| Trochozonites | 1 |
| Limax | 1 |
| Apera | 1 |
| Vitrina | 7 |
| Nanina | 6 |
| Conulus | 2 |
| Patula | 2 |
| Pella | 44 |
| Dorcasia | 8 |
| Phasis | 1 |
| Sculptaria | 2 |
| Helix (inc. sed.) | 4 |
| Rachis | 1 |
| Pachnodus | 3 |
| Buliminus (?) | 4 |
| Pupa | 20 |
| Vertigo | 2 |
| Achatina | 18 |
| Livinhacea | 1 |
| Stenogyra | 4 |
| Coeliaxis | 1 |
| Succinea | 3 |
| Vaginula | 2 |
| Cyclophorus | 1 |
| Cyclostoma | 7 |
| Cyclotus (?) | 1 |
| Blanfordia | 1 |
St. Helena.—The Molluscan fauna of St. Helena is perhaps the most puzzling, as regards its geographical affinities, of any in the world. It consists of 29 peculiar species of land Mollusca (fresh-water species being unknown), 19 of which are recently extinct, partly owing to the destruction of the forest, but are found in considerable abundance in a state of good preservation.[375] The genera are—