SOUTHERN ARABIA SOUTH AFRICA 



AraT)ia the mixture of types produces curious results : tlie Helix, 

 Cl(insili((, and Vitrina being Palaearctic, the Limicolaria and 

 all the operculates Ethiopian, while the single TrorJiomorplia 

 is Indian. Indian influence, indeed, conies out unmistakably 



Fig. 219.— Tiphubia Ilorci E. A. Smitli, 

 L. Tanganyika. • 



Fig. 220. — Mollusca cliarac- 

 teristicofL. Tanganyika: A, 

 Na.sso/)sis nassa Woodw. ; 



B, Sjickia zonata Woodw. ; 



C, Si/rnolopsis lacustris E. 

 A. Smith. 



throughout the province. Thus in Socotra there are two Cyrlo- 

 topsis, in Abyssinia two Africario7i (closely related to the Indian 

 GiTasia), two Microcystyis, and a Glessida, and in the Scioa dis- 

 trict there is a Sitfda. The fresh-water Mollusca of Socotra are 

 Indian forms. 



(2) The South African Sub-region. — The principal charac- 

 teristic of the Mollusca of S. Africa is 

 the occurrence of numerous small species 

 of Helicidae, belonging chiefly to the 

 groups PcUa, Fhasis, Dorcasia, aiul 

 Scidptaria, all of which are practically 

 peculiar. Carnivorous genera are also 

 prominent, Ennca here attaining its 

 maximum. lihyfida (to which several 

 species still regarded as Fella belong) is 

 common only to the S. racific and Aus- 

 tralasia, and forms, with Isidora among 

 the fresh -water pulmonates, a remarkable 

 liid< (if connexion. Aeropc, the largest 

 (jf all helicoid carnivorous genera, and 

 Chlamydepliorus, a carnivorous slug with 

 an internal sliell, are peculiar. Achatina 

 is still abundant, but Liviicolaria is wanting. Lichdtacca, a 



Fk;. 221. — AcJmtma zebra 

 Lam. , S. Africa, x ^. 



