1890.] MARINE MOLLXJSCA OF ST. HELENA. 249 



tended to assimilate, to some extent, the faunas of the West Indies 

 and West Africa by transmitting from place to place the pelagic fry 

 of some of the species, and the adult forms and the ova of others 

 attached to floating sea weed. 



Not more than fourteen species in this collection belong to forms 

 which occur in the Indo-Pacific region. This comparative paucity 

 of species common to these two regions is probably, in a great 

 measure, attiibutable to the cold Antarctic currents, which, flowing 

 northward to the Cape of Good Hope, bar the emigration of species 

 from the Indian Ocean into the Atlantic. Semper ' refers to the 

 sudden and marked change in the fauna on rounding the Cape, 

 the result of different currents and temperature. 



The only list of species from St. Helena which has yet appeared 

 is that prepared by Jeffreys', which was based upon a collection 

 made by Mr. Melliss, who, in his book on St. Helena (pp. 1 13-128), 

 has reproduced and somewhat amplified it. In this list only forty- 

 one marine species are enumerated, the majority consisting of shells 

 of fairly large dimensions, which, with one exception {Osirea crista- 

 guJli), were all picked up on the shore. 



This list did not contain all the species which had been previously 

 recorded from the island, at least half a dozen forms being omitted. 



The large proportion of new species hereafter described, most of 

 them very small, is not therefore altogether surprising, as so little 

 was previously known of this f.iuna. 



Thanks to Capt. Turton's energy, as many as 138 additional 

 named species are now added to the list, bringing up the total of 

 known forms to 1/8. 



This number, however, does not at all approximate the total of 

 the species which really exist around St. Helena : for, in addition 

 to those which I have been able to determine, there is a considerable 

 number, nearly a hundred species, which, on account of their imma- 

 ture or bad condition, could not be satisfactorily identified or 

 described. Btsides, whenever more extensive dredging is carried 

 on, many additional species will doubtless be discovered ^. 



A certain number of species have been described from St. Helena 

 which in reality do not inhabit that region. This mistake has arisen 

 from the misspelling of St. Elena on the west coast of America. 

 The species are : — (1) Cancellaria tessellata, Sowerby ; (2) C. ohtusa, 

 Kiener (non Deshayes)=C. solida. Sow. ; (3) Marginella granum, 

 Kiener=^ra^o scabriuseula. Gray ; (4) Purpura undata, Lamarck, 

 partim=P. biserialis, Blainv. ; (5) Ostrea columbiensis, Hanley ; 

 (6) Circe fiuctuata. Sow. ; (7) Strombus granulatus. Gray *. 



1 Animal Life, p. 278. - Ann. Mag. Nat. Hist. 1872, vol. ix. pp. 262-4. 



^ Specimens of Cyprcea iestudinaria, C. moneta, C. arabica, and Placuna sella 

 wei-e obtained by Capt. Turton as St. Helena shells ; but he shrewdl}- doubted 

 their genuineness. He observes, " ships from all parts of the world touch here, 

 often bringing shells which are got by the natives, and then offered as island 

 shells." This is evidently the true explanation of the presence of these species 

 at St. Helena. 



* Species 1 to 4 are quoted from Kiener's ' Icon. Coq. Viv.,' and 5, G, and 7 

 from ileeve's ' Conch. Icon.' 



