ABSTRACT
The synopsis of species to be presented in Chapters 3 and 4 covers Africa, Madagascar and the Mascarene Islands, and includes snails likely to be found in moderately saline coastal habitats such as mangrove swamp. Two families are dominant (Table 2.1), the Thiaridae and the Planorbidae, which together contribute about half of the totals for both genera and species. Few species found in tropical Africa occur also north of the Sahara Desert, and likewise few species of the Mediterranean region extend southwards into the tropics. Faunal composition and biogeography are discussed in Chapter 12; here the contributions of the different families are briefly summarised.
