98 MANUAL OF THE MOLLUSCA. 



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

 the most part different — Potamides decoUatus, Clionella sinuata, 

 and an Assiminea inhabit brackish waters. 



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 Bulimus, 

 Cydostoma 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 Pupd) 

 common to Madagascar. Bulimus guillaini, Cydostoma gratum, 

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



Very 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, BuUmulus, AcJia- 

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

 Achatina Rodatzi and allisa, Cydostoma Creplini and Zangue- 

 larica ; Pupa cerea is common to Zanzibar and Madagascar. 



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

 rates — Helix 2S sp., Bulimus 6, Succinea 14, Pupa 1, Achatina 4 

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

 and 32 Cyclostomido}. chiefly of .the section with spiral ridges 

 {Tropidophora), 3 of the division Otopoma. Cydostoma 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 Jiuminea, 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. . 



Hdix russeola and Achatina simpularia are found in Mayotte ; 

 Cydostoma pyrostoma in Mayotte and Madagascar. 



