114 
ST. HELENA. 
the late Professor E. Forbes in the Quarterly Journal of the Geological 
Society of London, for August, 1852. In the opinion of the last- 
named author ‘ a closer geographical relationship between the African 
and American continents than now maintains is dimly indicated’ by 
the marine mollusks of St. Helena ; and 1 the information we have 
obtained respecting the extinct and existing terrestrial mollusks of 
this isolated fragment of land would seem to point in the same direc- 
tion, and assuredly to indicate a closer geographical alliance between 
St. Helena and the west [? east] coasts of South America than now 
holds.’ And in the Report of the British Association for 1851 will 
be found an abstract of a paper by the same distinguished naturalist, 
entitled, ‘ On some Indications of the Molluscous Fauna of the Azores 
and St. Helena.’ It is here stated that ‘ the marine mollusks [of 
St. Helena] would seem to point to the submergence of a tract of land 
probably linking Africa and South America before the elevation of 
St. Helena. Along the sea-coast of such a tract of land the creatures 
common to the West Indies and Senegal might have been diffused.’ 
I am not quite satisfied with this hypothesis, and I believe that more 
information is needed to support it. Some of the land-shells of St. 
Helena are European, and may have been introduced by the agency 
of man ; others are peculiar to the Island. A few of the marine 
shells are Mediterranean, while the gi-eater number are well-known 
inhabitants of the Indian Ocean and the West Indies ; all these 
may have originated anywhere. But it must be borne in mind that 
St. Helena is separated from Africa and South America in every 
direction by very deep water, which is nowhere less than 2000 
fathoms or 12,000 feet. It therefore seems scarcely probable that 
such an abyssal and extensive tract of the sea-bed could have been 
dry land or ‘sea-coast,’ in a geologically recent period, so as thus to 
account for the diffusion of littoral species such as Mytilus edulis, M. 
crenatus, and Littorina striata. I should be rather inclined to 
attribute the present distribution of the marine fauna of St. Helena 
(not to a supposed continuity of land between Africa and South 
America in that or any other direction, but) to the action and 
influence of the great Agulhas Current, which issues from the Indian 
Ocean and flows round the Cape of Good Hope northwards towards 
St. Helena, and thence past Ascension to the West Indies. The 
partial correspondence between the Mollusca of the Indian Ocean 
and of the Mediterranean may have been owing to the Guinea 
