98 MAKITAL OF THE MOLLUSCA. 



The species found at the Cape, Algoa Bay, Natal, &c., are for 

 the most part different — Potamides decoUatus, CUondla ainuatay 

 and an Assiminea inhabit brackish waters. 



Limax 4 



Arion 1 Limnsea 1 Paludina 3 



Physa 4 Neritina 1 



Vitrina 4 Physopsis 1 



Helix 35 Ancylus 1 CorMcula 



Succinea 4 Planorbis 3 Cyclaa , 



Bulimus 13 Pisidium , 



Pupa 6 Vaginulus 1 Unio , 



Achatina 7 Oncidium 1 Iridina 



Cyclostoma 6 Auricula 6 



5. Yemen — Madagascar. 



The S. W. Highlands of Arabia (Yemen) form a distinct 

 Botanical province isolated by rainless deserts to the north. 

 The land snails consist of a few species of Helix and BuUmus, 

 Cyclostoma lithidion, and 3 species of the section Otopoma, a 

 group also found in Madagascar. Two species are common to 

 the island of Socotra (No. 30), which also has a species (of Fupd) 

 common to Madagascar. BuUmus guillaini, Cyclostoma gratuw^ 

 modestum and Souleyeti are found on the island of Abd-el-Gouri. 



Yery few land shells have been collected on the mainland of 

 Eastern Africa, although it is a rainy region, and well wooded 

 in the southern part ; 5 species only are recorded from Moga- 

 doxa and Ibu, belonging to the genera Helix, Bulimulus, Acha- 

 tina, Pupa, and Otopoma. On the Island of Zanzibar are found 

 Achatina Rodatzi and allisa, Cyclostoma Creplini and Zangue- 

 harica ; Pupa cerea is common to Zanzibar and Madagascar. 



Madagascar itself is rich in land shells ; Dr. Pfeiffer enume- 

 rates — Helix 28 sp., BuUmus 6, Succinea 14, Pupa 1, Achatina 4 

 (one of which, eximia, is allied to A. Columna, of W. Africa), 

 and 32 Cyclostomidce, chiefly of the section with spiral ridges 

 {^Tropidophora), 3 of the division Otopoma. Cyclostoma carini- 

 ferum and Cuvieri are found on the Island of Nosse Be ; Helix 

 guillaini on S. Maria I. Amongst the fresh- water shells are 

 Melania amarula, Melanatria fluminea, and Neritina corona. 



The land shells of the Mascarene Islands are nearly all pecu- 

 liar; we are indebted to Mr. "W. H. Benson for most of the 

 information existing in respect to them. 



Comoro Islands. 



Helix russeola and Achatina simpularia are found in Mayotte ; 

 Cyclostoma pyrostoma in Mayotte and Madagascar. 



