412 



ISLAND LIFE. 



[part II. 



fifty are endemic, twenty-two are Asiatic but not African, while 

 twenty-eight are African but not Asiatic. This iraphes that the 

 more ancient connection has been on the side of Africa, while 

 a more recent immigration, shown by identity of species, has 

 come from the side of Asia; and it is probable that when the 

 flora of Madagascar is more thoroughly worked out, the same, or 

 a still greater African preponderance, will be found in that island, 



A few Mascarene genera are found elsewhere only in South 

 America, Australia, or Polynesia ; and there are also a con- 

 siderable number of genera whose metropolis is South America, 

 but which are represented by one or more species in Mada- 

 gascar, and by a single often widely distributed species in 

 Africa. This fact- throws light upon the problem offered by 

 those mammals, reptiles, and insects of Madagascar which now 

 have their only allies in South America, since the two cases 

 would be exactly parallel were the African plants to become 

 extinct. Plants, however, are undoubtedly more long-lived 

 specifically than animals — especially the more highly organised 

 groups, and are less liable to complete extinction through the 

 attacks of enemies or through changes of climate or of physical 

 geography ; hence we find comparatively few cases in which 

 groups of Madagascar plants have their only allies in such 

 distant regions as America and Australia, while such cases are 

 numerous among animals, owing to the extinction of the allied 

 forms in intervening areas, for which extinction, as we have 

 already shown, ample cause can be assigned. 



Curious Relations of Mascarene Plants. — Among the curious 

 affinities of Mascarene plants we have culled the following 

 from Mr. Baker's volume. Trochetia, a genus of Sterculiacese, 

 has four species in Mauritius, one in Madagascar, and one in 

 the remote island of St. Helena. Mathurina, a genus of Turner- 

 aceae, consisting of a single species peculiar to Rodriguez, has 

 its nearest ally in another monotypic genus, Erblichia, confined 

 to Central America. Siegesbeckia, one of the Compositse, con- 

 sists of two species, one inhabiting the Mascarene islands, the 

 other Peru. Labourdonasia, a genus of Sapotace£e, has two 

 species in Mauritius, one in Natal, and one in Cuba. Neso- 

 genes, belonging to the verbena family, has one species in 



