CHAr. XIX.] THE MADAGASCAR GROUP. 405 

 ^ 



limited areas where the physical conditions were especially 

 favourable, or where they were saved from the attacks of enemies 

 or the competition of higher forms. 



Fresh-water Fishes. — The only other vertebrates in the Sey- 

 chelles are two fresh-water fishes abounding in the streams and 

 rivulets. One, Haplochilus playfairii is peculiar to the islands, 

 but there are allied species in Madagascar. It is a pretty little 

 fish about four inches long, of an olive colour, with rows of red 

 spots, and is very abundant in some of the mountain streams. 

 The fishes of this genus, as I am informed by Dr. Giinther, 

 often inhabit both sea and fresh water, so that their migration 

 from Madagascar to the Seychelles and subsequent modification, 

 offers no difiiculty. The other species is Fundidus orihonotus, 

 found also on 'the east coast of Africa ; and as both belong to 

 the same family — Cyprinodontidse — this may possibly have 

 migrated in a similar manner. 



Land-shells. — The only other group of animals inhabiting 

 the Seychelles which we know with any approach to complete- 

 ness, are the land and fresh-water moUusca, but they do not 

 furnish any facts of special interest. About forty species are 

 known, and Mr. Geoffrey Nevill, who has studied them, thinks 

 their meagre number is chiefly owing to the destruction of so 

 much of the forests which once covered the islands. Seven of the 

 species — and among them one of the most conspicuous, Achatina 

 fidica — have almost certainly been introduced ; and the remainder 

 show a mixture of Madagascar and Indian forms, with a prepon- 

 derance of the latter. Five genera— Streptaxis, Cyathoponea, 

 Onchidium, Helicina and Paludomus, are mentioned as being 

 especially Indian, while only two — Tropidophora and Gibbus, 

 are found in Madagascar but not in India.^ About two-thirds 

 of the species appear to be peculiar to the islands. 



Mauritius, Bourbon and Rodriguez. — These three islands 

 are somewhat out of place in this chapter, because they 

 really belong to the oceanic group, being of volcanic formation, 

 surrounded by deep sea, and possessing no indigenous mammals 

 or amphibia. Yet their productions are so closely related to those 

 of Madagascar, to which they may be considered as attendant 



' '^Additional Notes on the Land-shells of the Seychelles Islands.'' By 

 Geoffrey Nevill, C.M.Z.S. Froc. Zool Soc, 18r>9, p! 61. 



