LAND REGIONS. 191 



1 Melanin, 4 Pirena, a few Limnffia, Physa, Planorbis, Ampnllaria, 

 Paludomus, Paludiiia, Lanistes, etc. A very doubtful Unio and 

 a C^'clas are the only bivalves found in this region. As might 

 be expected, Madagascar, besides the special forms of the region, 

 possesses some purely African genera ; but these may haA^e been 

 introduced. The dunes of Cape St. Marie, where occur the 

 bones of the gigantic extiuct bird, ^pyornis, contain a few 

 equally extinct shells, mixed with those of species still living. 



About fifty species ai'e known from the Comoro Islands, 11 of 

 which are Ennea. 



The island of Bourbon contains 69 species, 9 of which are 

 operculated ; and that of Mauritius a richer favina, including 28 

 species of Gribbus — of which form it may be considered the 

 metropolis — 8 of Omphalotropis, etc. Gibbus Lyorietianus, one 

 of the most bizarre-looking of land shells, appears to be rapidly 

 becoming extinct. The island of Rodriguez possesses a fauna 

 resembling that of Mauritius. The Se^^chelles contain two large 

 Helices (Stylodonta) and the singular slug Mariella Dussumieri. 

 The genera Cyathopoma, Leptopoma and Helicina are repre- 

 sentatives of Asiatic forms, as well as the species Ennea bicolor 

 and Helix aimilaris — the two latter acclimated throughout this 

 region. 



11. Afro-Arabio Region. 



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

 botanical province isolated by rainless deserts to the north, 

 Abyssinia, the island of Socotra, and the African shore of the 

 Gulf of Aden form a region but little known, but which differs 

 sensibly from the African and Indian faunas. In Arabia and 

 Socotra, Ennea, Vitrina, Buliminus, Opeas, Csecilianella, Pupa, 

 Coelostele,Isidora, Cl^-clostoma, Otopoma, Lithidion and Melania 

 are found. There are no Helices ; Buliminus 14 sp. 



The fauna of Abj^ssinia is curious alike for the absence of 

 African genera, such as ^Etheria, Iridina, Galatea, Achatina, 

 Lanistes, and for the intrusion of forms from other regions. The 

 latter include 2 species of Limicolaria, several European species 

 (Succinea, Limnsea, Helix), some Buliminus, etc. There is not 

 a single species of operculated land shells, but there are 2 

 Clausilia, 12 Pupa, 8 Vitrina, 9 Subulina; Paludina occurs, but 

 no Ampullaria. There are 3 Uniones, a Corbicula and a Cyclas. 



12. Indian Region. 



This province has been very well studied, and the rich results 

 are included in the magnificent " Conchologia Indica," b}^ Hanley 

 and Theobald, published in 18*16. Among the most remarkable 

 terrestrial genera may be cited : Anadenus 2 sp., Vitrina 12, 

 Succinea 10, Lithotis 2, Nanina (sections Macrochlamys, Xesta, 



