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VL SAINT HELENA. 



The Gastropods of St. Helena are but few in number, as regards 

 species ; and yet the fauna is not quite so poor as has generally 

 been supposed* Considering the smallness of its area, its ex- 

 treme isolation, and the basaltic character of its rocks, we should 

 hardly expect that Molluscous life in the island would be very 

 greatly developed ; and I do not think, therefore, that twenty-nine 

 specific formSj apart from certain important varietal modifica- ■ 

 tions, can be regarded as much below the average of what may 

 be said to obtain in most other spots whicli are more or less 

 similarly circumstanced. True it is that about half of them 

 (indeed imore than half, if only the essentially indigenous ones 

 be taken into account) are now extinct, occurring mei-ely in a 

 subfossil condition ; but this is only what the deteriorated 

 nature of the country might have led us to anticipate, — the 

 wholesale destruction of its aboriginal wood liaving so far altered 

 the climatical equilibrium as to bring entire districts, which 

 must once have been comparatively fertile, into a hopeless state 

 of arid sterility. But at a former epoch, when the forests of 

 gumwood and ebony clothed many of the outer regions above 

 the corst, and the great central ridge was an unbroken jungle 

 of cabbage-trees, asters, and tree-ferns, it is easy to understand 

 how the increased moisture and the presence of swamps would 

 have afforded conditions better suited for the requirements of 

 the Pulmonifera, and sustained Succlnece and Bulimi which 

 have now either totally died out, or else linger sjaaringly on 

 under a more or less depauperated aspect. 



Although the genuine Bidimi of St. Helena may be said to 

 ))elong essentially to a past epoch, two at least of them (the B. 

 helena, Quoy, and the exulatus, Bens.) cannot long have become 

 extinct. Indeed it is far from impossible that they may still 

 survive on some of the rocky and well-nigh inaccessible slopes 

 in the extreme north of the island, — many of the bleached ex- 

 amples of the B. helena which lie scattered loosely on the sum- 

 mit of the Barn liaving not only their outer cuticle but even 

 tlieir colour almost completely preserved. Mr. MellisSj in 



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