CHAP. XIX.] 
TIIE 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. Gunther, 
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 Fundulus orthonotus, 
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 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 
fulica — 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 . 1 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 
1 “Additional Notes on the Land-shells of the Seychelles Islands.” By 
Geoffrey Nevill, C.M.Z.S. Proc. ZooL Soc. 1869, p. 61. 
