176 MADAGASCAR. [CH. Ill 



have carried with it the single species S. carinata, which 

 extends to so northerly a situation. 



" Lemuria." 



By some naturalists, Madagascar is believed to be the 

 remnant of a great continent extending across the Indian 

 Ocean, and has been referred to as Lemuria. Some of the 

 islands lying to the north of Madagascar will be in this 

 event other scraps of the same continent. Among these 

 islands the Seychelles at least offer other evidence of 

 being the last fragment of a vanished continental expanse : 

 they are a group of about thirty islets lying 700 miles, to 

 the north of Madagascar. Though oceanic in most of 

 their characters they are composed of "granitoid or 

 gneissoid" rocks, thus arguing original continental con- 

 ditions. In spite of this fact in their geological structure 

 they do not possess a single indigenous mammalian 

 inhabitant. This fact, it may be incidentally pointed out, 

 is of importance ; it shows that the true remains of 

 continents may be without mammals and that the absence 

 of mammalia is not always to be relied on as an infallible 

 sign of an oceanic island. Their small size may have 

 caused the decay of the original mammalian fauna, an 

 argument that can of course be applied to the doubtful 

 case of the Galapagos archipelago (see below). There are 

 however four Amphibia, a more infallible sign of a former 

 continental connection. These are a frog, Rana mascarina, 

 which is widely distributed in this region of the world, 

 a peculiar Tree frog and two Csecilians, that group of 



