1878.] HEMIPTERA OF ST. HELENA. 449 



Regarding the Mollusca, the late Edward Forbes thought that 

 both the terrestrial and marine species dimly indicated a closer geo- 

 graphical relationship between the African and American continents 

 than now maintains. " The marine mollusks 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." Commenting on this sugges- 

 tion, Mr. Gwyn Jeffreys 1 writes, " I am not quite satisfied with this 

 hypothesis, and I believe that more information is needed to support 



it 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 and 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 be- 

 tween 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." 



Mr. Andrew Murray, whose loss to science we have had so recently 

 to deplore, has given 2 a considerable amount of attention to the 

 origin of the fauna of St. Helena. After stating his conviction that 

 there at one time existed a land communication, now at the bottom 

 of the Atlantic, between the northern and southern hemispheres, and 

 arguing that there are only three great Coleopterous faunae or 

 stirpes (the Indo-African, the Brazilian, and what he calls, for want 

 of a better name, " the microtypal stirps "), he proceeds to say : — 

 " St. Helena, that great puzzle of naturalists, is a crucial test to my 

 hypothesis of a communication between the northern and southern 

 hemispheres by an Atlantic continent ; if that link snaps, the whole 

 chain will fall to the ground I say that its fauna is cer- 

 tainly microtypal, and, if so, almost necessarily a branch of the 

 Atlantic type of that stirps ; there is nothing else microtypal for it 

 to be attached to. Some three years ago Dr. Hooker gave an admi- 

 rable Lecture on Oceanic Islands, in which he discussed the origin 

 of the flora of St. Helena, and on the whole seemed inclined to refer 

 it to Africa. More in the spirit of ' audi alteram partem ' than from 

 any settled conviction of my own, I wrote a reply, in which I gave 

 some reasons for thinking that it might more probably have been 



1 Ann. & Mag. Nat. Hist. April 1872 ; Melliss, I. c.'\i. 114. 

 3 •' On the Geographical Kelations of the Chief Coleopterous Fauna," Journ. 

 Linn. Soc. xi. no. 4D. 



