Mr. J. Gwjn Jeffreys on the Mollusca of St. Helena. 263 



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 intro- 

 duced by the agency of man; others are peculiar to the island. 

 A few of the marine shells are Mediterranean, while the greater 

 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 12000 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. crenatusj 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 correspon- 

 dence between the Mollusca of the Indian Ocean and of the 

 Mediterranean may have been owing to the Guinea Current, 

 as well as to a passage which formerly existed across Africa 

 in the line of the Sahara — a very wide tract, which certainly 

 was submerged during the quaternary period. I must admit, 

 however, that our information as to the marine Mollusca of 

 the South- Atlantic region, including St. Helena, is very scanty 

 and unsatisfactory. The only dredging that has ever, to my 

 knowledge, been attempted off St. Helena was made by Dr. 

 Wallich in 1857, on his return home from India; and this 

 was at a depth of from 20 to 30 fathoms. It produced a few 

 small shells, which Dr. Wallich kindly gave me. Many of 

 these appear to be undescribed species. The promised cir- 

 cumnavigation expedition, under the auspices of the Royal 

 Society, will doubtless enable us to learn something of the 

 South -Atlantic fauna. 



Mr. Edgar Smith will describe such of the species in the 

 subjoined list and of those dredged by Dr. Wallich as are new 

 to science. Mr. Melliss has presented to the Britisli Museum 

 all the specimens, with the exception of a few duplicates, 



