LUSITANIAN REGION. 389 



Helix simolata, Syria — Egypt — Lancerotte. 



„ Michaudi, summit of Porto Santo — Teneriffe ? 



„ cyclodon, Azores — Canaries — C. de Yerdes. 



„ advena, (= eruhescens I.owe,) Madeira — Azores — St. Vincent. 



„ plicaria and planorbella, Canaries — Porto Rico ? 

 Bulimus subdiapliauus, Canaries — Azores — C. de Verdes. 



„ bcelicatus and badiosus, Canaries— St. Thomas ? 



Ascension. This barren volcanic island, in the midst of the Atlantic 

 Ocean, is not known to possess any terrestrial Pulmonifera beside a slug, 

 the Limax Ascensionis, Mr. Benson thinks that some Helicidce might pos- 

 sibly be found on the Green Mountain, 2840 feet high, where the garrison 

 have their garJeus. Mr. Darwin remarks " we may feel sure that at some 

 former epoch, the climate and productions of Ascension were very different 

 from what they now are." 



St. Helena. (No. 28 of Map). 



The Island of St. Helena is 800 miles S. E. of Ascension, and 1200 from 

 the nearest African coast of Beuguela. It is entirely volcanic. The indigenous 

 plants are all peculiar, and not more related to those of Western Africa than 

 to Brazil.* The land shells are also peculiar ; 13 species have been described ; 

 viz : — Helix, 3 sp. Bidimus 5, Achatina 2, Fv/pa 1, Succinea {Helisigd), 2. 

 As many more have been met with only in the condition of dead shells, rarely 

 retaining their colour and translucency. They are found beneath the surface- 

 soil in the sides of ravines worn by the heavy rains, at a height of 1200 to 

 1700 feet ; " their extinction has probably been caused by the* entire destruc- 

 tion of the woods, and the consequent loss of food and shelter, which occurred 

 during the early part of last century." — (Darwin's Journal, p. 488). A living 

 Bulimus, related to the extinct B. Blofieldi, is found feeding on the cabbage- 

 trees, only on the highest points of the Island. 



Extinct land-shells of St. Helena.-^ 



Bulimus auris vulpinus. Bulimus relegatus. 



„ Darwini. Helix bilamellata. 



„ Blofieldi. „ polyodon. 



„ Sealei. „ spurca. 



„ subplicatus. „ biplicata. 



„ terebellum. „ Alexandri. 



,, fossilis. Succinea Bensoni. 



The large Bulimus, (fig. 91, p. 164) has no living analogue in Africa, 



* " It miglit perhaps have been expected that the examination of the vicinity of 

 the Congo would have thrown some light on the origin, if I may so express myself, of 

 the Flora oiSt. Helena. This, however, has not proved to be the case; for neither 

 has a single indigenous species, nor have any of the principal genera characterising 

 the vegetation of that Island, been found either on the banks of the Congo, or on any 

 other part of this coast of Africa."— R. Brown, Appendix to Captain Tuckey's Narra- 

 tive of the Congo Expedition, (p, 476.) 1818. 



t G. Sowerby in Darwin's " Volcanic Islands," p. 73. Forbes, Journ. Geol. Sec* 

 1&J2, p. 197.— Benson, An. Xat. Hist. 1851, VII. 263. 



