9G MANITAL OP THE M0LLT7SCA. 



volcanic. The iudigenous plants are all peculiar, and not rnoro 

 related to those of Western Africa than to Brazil.* The land 

 shells are also peculiar ; 13 species have been described, viz. • — 

 Helix, "^ sp, Buliraus 5, Achat hia 2, Fiqm 1, Succinea {Helisiga) 

 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 1,200 to 1,700 feet. 

 * ' Their extinction has probably been caused by tho entire de- 

 struction 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 BulimuSy related to the 

 extinct B. Blofiddi, is found feeding on the cabbage-trees, only 

 on the highest jDoints of the island. 



Extinct Land-shells of St. Helena, f 



Buliinus amis viJpinua. Bulimus relegatus. 



„ Darwini. Helix bilamellata. 



„ Blofieldi. „ polyodon. 



„ Sealei. „ epurca. 



„ subplicatua. „ biplicata. 



„ terebellum. „ Alexandri. 



„ fossilis. Succinea Bensoni. 



The large Bulimus, (fig. 123, p. 291), has no living analogue in 

 Africa, but is a member of a group characteristic of tropical 

 America (to which the names Plecochilus, Pachyotis and Caprella 

 have been given), including B. signatus, B. hilahiatus, B. goni- 

 ostomus, and especially B. sulcatus (Chilonopsis, Fischer) of St. 

 lago.J The four next species belong to the same type, but are 

 smaller and slenderer. ' ' The marine mollusks of the coast of 

 St. Helena would lead us to infer the very ancient isolation of 

 that island, whilst at the same time a pre-existing closer 

 geographical relationship between the African and the American 



* " It might perhaps have been expected that the examination of the nchiity of the 

 Congo would have thi'own some light on the origin, if I may so express mj-self, of the 

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

 sinj^Ie indigenous species, nor have any of the prhicipal 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 Narrative of 

 the Congo Expedition (p. 476). 181S. 



t G. Sowerby in Darwin's " Volcanic Islands," p. 73, Forbes, Joui-n. Geol. Soc. 

 1852, p. 197.— Benson, An, Nat. Hist, 1851, vii, 263. 



X As Dr, Pfeiffer includes this (with a sign of doubt) amongst the sjnonyms of 

 B. auris-vulpimis, he must have suspected that the specimens came from St. Helena 

 and not from St. lago. The only other group of Bulimi resembling the St. Helena 

 shells occurs in the Pacific Islands •.—JRuIimns Caledonicus at Mulgrave I., B. aims 

 tcvina at tlie Solomons, and B. shongi in New Zealand. 



