INSULAR FLORAS. 47 1 



to H. attenuata, a species inhabiting the Cameroons, West 

 Africa, at an elevation of over 7000 species. Wellstedia 

 socotrana, figured on the same plate as the Habenana, is a 

 new endemic o-enus of anomalous structure, which Balfour 

 is inclined to regard as an aberrant member of the 

 Borragineoe, from which it diverges in its capsular fruit, 

 pendulous ovules and an embryo with accumbent cotyledons. 



One of Balfour's most detailed tables deals with the 

 affinities and other points of the endemic phanerogams of 

 the flora of Socotra ; some of the particulars of which I 

 have already given. This is followed by a table showing the 

 distribution of the genera with endemic species, and several 

 other tables which it is unnecessary to designate. The 

 sum of these facts shows that the flora is essentially African ; 

 but, apart from the general Asian element, there are forms 

 which have "relations only in restricted districts in India, 

 or further east, but which have no connections in the inter- 

 mediate regions ". There is also strong evidence that it is 

 a very old flora, though in remote antiquity the island was 

 joined to the mainland of Africa ; and the presence of 

 highly specialized African types, now occurring sporadically 

 in distantly separated situations westward to the Atlantic 

 Islands and southward to the Cape of Good Hope, together 

 with isolated instances of exceedingly rare types represented 

 in more distant countries in the same isolated manner, 

 strongly support the view of an earlier tropical African 

 flora than the present, now only existing in widely separated 

 areas. The genera Aloe, Draccena (of the D. Draco group) 

 and cereus-like species of Euphorbia are familiar examples 

 of this doubtless very ancient flora. 



Schweinfurth himself says on this point (52), that out of 

 a collection of 790 species of vascular plants made by him 

 in the northernmost part of the Abyssinian highlands, in 1 89 1 , 

 half had been collected by him in Arabia the previous year; 

 whilst three-fourths of the remaining half of his Arabian 

 collection had been found by other collectors in some part 

 of Abyssinia. According to this rough computation at 

 least seven-eighths of the species are common to both sides 

 of the Red Sea. 



