CHAP XIX THE MADAGASCAR GROUP 435 



apart, and the sea between them is less than 1,000 fathoms 

 deep, while on each side it sinks rapidly to depths of 2,400 

 and 2,600 fathoms. We have therefore no reason to 

 believe that they have ever been connected with Mada- 

 gascar, and this view is strongly supported by the character 

 of their indigenous fauna. Of this, however, we have not 

 a very complete or accurate knowledge, for though both 

 islands have long been occupied by Europeans, the study 

 of their natural products was for a long time greatly 

 neglected, and owing to the rapid spread of sugar cultiva- 

 tion, the virgin forests, and with them no doubt many 

 native animals, have been almost wholly destroyed. There 

 is, however, no good evidence of there ever having been 

 any indigenous mammals or amphibia, though both are now 

 found and are often recorded among the native animals.^ 



The smaller and more remote island, Rodriguez, is also 

 volcanic ; but it has, besides a good deal of coralline rock, 

 an indication of partial submergence helping to account 



^ In Maillard's Notes sur VIsle de Rhmion^ a considerable number of 

 mammalia are given as ** wild, "such as Lemur mongoz and Centetes setosus, 

 both Madagascar species, with such undoubtedly introduced animals as a 

 wild cat, a hare, and several rats and mice. He also gives two species of 

 frogs, seven lizards, and two snakes. The latter are both Indian species 

 and certainly imported, as are most probably the frogs. Legouat, who 

 resided some years in the island nearly two centuries ago, and who was 

 a closer observer of nature, mentions numerous birds, large bats, land- 

 tortoises, and lizards, but no other reptiles or venomous auimals except 

 scorpions. We may be pretty sure, therefore, that the land-mammalia, 

 snakes, and frogs, now found wild, have all been introduced. Of lizards, 

 on the other hand, there are several species, some peculiar to the island, 

 others common to Africa and the other Mascarene Islands. The following 

 list by Prof. Dumeril is given in Maillard's work : — 



Platydact^lus cepedianus, Hemidactylus frenatus. 



„ ocellatus. Qongylus bojerii. 



Hemidactylus peronii. Ablepharus pcronii. 



,, mutilatuB. 



Four species of chameleon are now recorded from Bouibon and one from 

 Mauritius (J. Reay Greene, M.D., in Pop. Science Rev. April, 1880), but 

 as they were not mentioned by the old writers, it is pretty certain that these 

 creatures are recent introductions, and this is the more probable as they 

 are favourite domestic pets. 



Darwin informed me that in a work entitled Voyage ct VIsle de France, 

 par un Officier du Roi, published in 1770, it is ^-tated that a fresh -water fish 

 had been introduced from Batavia and had multiplied. The writer also 

 says (p. 170) : ^' On a essaye, 07iais sans succes, d^y transporter des grenouilles 

 qui mangent les oeufs que les nwustigues deposent sur lesljcaux stagnaiites," 

 It thus appears that there were then no frogs on the island. 



