COOKE: GEOGRAPHICAL DISTRIBUTION OF MOLLUSCA. 1 33 



The fresh-water molluscan fauna of Madagascar contains further 

 unmistakable traces of Indian relationship. Thus we find two species 

 of Paludomus, a genus whose metropolis is Ceylon, India, and 

 Further India, and which is barely represented on the Seychelles 

 and in the Somali region of the African mainland. The genus 

 Melanatria, which is quite peculiar to Madagascar, has its nearest 

 affinities in the Cingalese and East Indian faunas. Two species of 

 Bithynia occur, another genus whose metropolis is India, and which 

 is quite strange to tropical Africa. Several of the Melanice are of 

 a type entirely wanting in Africa, but common in the Indo-Malay 

 region. Not a single one of the characteristic African fresh-water 

 bivalves (Afutela, Spatha, Aetheria, Galatea, &c.) has been found 

 in Madagascar. On the other hand, certain African genera of 

 gasteropoda, such as Cleopatra and Isidora, occur, indicating, in 

 common with the land mollusca, that an ultimate land connection 

 of Madagascar with Africa must have taken place, but that it 

 occurred at an immeasurably remote period. 



Nossi Be and Nossi Comba. — The Mollusca of these two small 

 islands, which lie off the N.E. of Madagascar, are well known. They 

 show, as would be expected, close relationship to Madagascar itself, 

 the great Helicidce and Cyclostomidce both occurring freely, together 

 with a single Melanatria. Omphalotropis, not yet recorded from 

 Madagascar, but abundant in the Mascarenes, is found, this being 

 the extreme of its westward range. Perhaps the most remarkable 

 feature is the occurrence of two species of the Indian genus Sitala 

 (which may therefore be looked for in Madagascar), and one of 

 Geostilbia. 



MOLLUSCA OF MADAGASCAR.* 



Besides those contained in this list, 18 sp. "Heli.v," 2 " Bulijuus" and 11 "Cyclostoma," 

 have been described, but not figured, in Bull. Soc. Philoni. (7) x. (1886), pp. 124, 139, 182. 



