460 



APPENDIX 



sion are really indigenous, namely, Hedyotis adscensionis and Euphorbia 

 origanoides, both of which are endemic. The first is more nearly 

 related to African and Asiatic species than it is to the St. Helena, 

 H. arborea. The second has its nearest ally in E. trinervia from the 

 Guinea coast, there being no indigenous species of Euphorbia in 

 St. Helena. Current-borne seeds could only reach Ascension through 

 the agency of the Main Equatorial Current, which would carry drift 

 to it from tropical Africa and from the extra-tropical southern 

 part of the continent, the South African Current here coming into 

 play. 



St. Helena, lying as it does in the track of the South Equatorial 

 Current, which is fed by the off-shore waters of the South African 

 Current, would not receive any African drift except from the southern 

 extremity of the continent ; but through the intermediate agency of 

 the South Atlantic Connecting Current it would be the recipient of 

 drift from the South American region gathered by the Brazil Current 

 between Cape St. Roque and the River Plate. It would be quite 

 cut off by the currents from Ascension and could receive no drift 

 from the north, Dr. White's contention that the flora and fauna 

 arrived from the north in the direction of the Cape Verde Islands 

 being quite untenable (quoted by Scharff, p. 388). If the currents 

 have been concerned in stocking the island, they would have brought 

 to it seeds from South Brazil and the River Plate as well as from 

 the Cape. It is noteworthy that whilst Hooker finds the most 

 characteristic affinities of the flora in southern extra-tropical Africa, 

 Hemsley, following Bentham, points to equal or closer affinities 

 between its arboreous Composite and South American types (Ibid., 

 III., 59). 



Though there is no evidence that the plants concerned are dis- 

 tributed by the currents, it is remarkable that this agency, if effec- 

 tive, might possibly explain in both Ascension and St. Helena the 

 affinities determined by the botanists. Yet from the endemism of 

 the genera with South American affinities, it may be inferred in the 

 case of St. Helena that whilst the South American connection is 

 largely a thing of the past, that with South Africa has been main- 

 tained up to relatively recent times. (The system of currents pre- 

 vailing in the South Atlantic is discussed in Chapter III. and Note 18.) 



Note 12 (pp. 51-55). 



Bottle-drift on the Azores. 



The answer to the question as to the source of the vegetable drift 

 stranded on the Azores is plainly given in the results tabulated below 

 for bottle-drift. All the seeds stranded there must come from the 

 west, namely, from the coasts of the New World between Newfound- 

 land and the West Indies. Nothing comes from the eastward, and 

 it will subsequently be shown that bottles dropped into the sea in 

 the vicinity of this group either display the same easterly drift or are 

 carried south into the North Equatorial Current, ultimately reaching 

 the West Indies. This conclusion applies to all seasons of the year, 



