410 
ISLAND LIFE. 
[part II. 
situated about fourteen miles north-east of Mauritius, possesses 
a snake which is not only unknown in Mauritius, but also in any 
other part of the world, being altogether confined to this minute 
islet ! It belongs to the python family, and forms a peculiar 
and very distinct genus, Casarea, whose nearest allies seem to 
be the Ungalia of Cuba and Bolgeria of Australia. It is hardly 
possible to believe that this serpent has very long maintained 
itself on so small an island; and though we have no record of 
its existence on Mauritius, it may very well have inhabited the 
lowland forests without being met with by the early settlers ; 
and the introduction of swine, which soon ran wild and effected 
the final destruction of the dodo, may also have been fatal to 
this snake. It is, however, now almost certainly confined to 
the one small islet, and is probably the land-vertebrate of most 
restricted distribution on the globe. 
On the same island there is a small lizard, Thyrus boyeri , 
also a peculiar species and genus, but this is recorded from 
Mauritius and Bourbon as well, though it appears to be rare in 
both islands. As Round Island is connected with Mauritius by 
a bank under a hundred fathoms below the surface, it has pro- 
bably been once joined to it, and when first separated would 
have been both much larger and much nearer the main island, 
circumstances which would greatly facilitate the transmission 
of these reptiles to their present dwelling-place. 
Flora of Madagascar and the Mascarene Islands . — The botany 
of the great island of Madagascar has been perhaps more 
thoroughly explored than that of the opposite coasts of Africa, so 
that its peculiarities may not be really so great as they now 
appear to be. Yet there can be no doubt of its extreme 
richness and grandeur, its remarkable speciality, and its anoma- 
lous external relations. It is characterised by a great abundance 
of forest-trees and shrubs of peculiar genera or species, and 
often adorned with magnificent flowers. Some of these are 
allied to A frican forms, others to those of Asia, and it is said 
that of the two affinities the latter preponderates. But there 
are also, as in the animal world, some decided South American 
relations, while others point to Australia, or are altogether 
isolated. 
