433-4 ISLAND LIFE 



streams and rivulets. One, Haplodiihts '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 difficulty. The other species is F^mdnhts 

 orthonohcs, found also on the east coast of Africa ; and as 

 both belong to the same family — Cyprinodontidae — 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 

 completeness, are the land and fresh-water mollusca, 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 ftdica — 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 are mentioned as 

 being especially Indian, while only two are found in 

 Madagascar but not in India.^ Only one-fourth of the 

 species appear to be peculiar to the islands, according to the 

 latest enumeration by Von Martens and Weigmann in 1898. 



MauritiiLS, Bouiion 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 satellites, that it is; 

 absolutely necessary to associate them together if we wish to 

 comprehend and explain their many interesting features. 



Mauritius and Bourbon are lofty volcanic islands, 

 evidently of great antiquity. They are about 100 miles 



1 "Additional Notes on the Land-shells of the Seychelles. Islands." By 

 Geoffrey Nevill, C.M.Z.S. Proc. Zool. Soc, 1869. p. 61. 



