1852.] FORBES EXTINCT LAND-SHELLS OF ST. HELENA. 197 



4. On the Extinct Land-Shells of St. Helena. 

 By Prof. Edward Forbes, F.R.S., G.S. 



[Plate V.] 



The presence in St. Helena of considerable numbers of a remarkable 

 extinct univalve once supposed to be of marine origin, and described 

 by mistake as from China, but afterwards proved to be a land-snail 

 of the genus Bulimus, has long been known. This shell, to which 

 the name of Bulimus auris-vulpina (Ferussac) has been given, is of 

 considerable dimensions, and hence had attracted the notice of col- 

 lectors. Their true position was first indicated by Mr. Scale, a resi- 

 dent of the island, who communicated other species found with this 

 and elsewhere in the island to Mr. Darwin. These are described by 

 Mr. G. B. Sowerby in the appendix to Mr. Darwin's work upon 

 Volcanic Islands. There are other forms of land-mollusks, not now 

 known as living species, associated with it. 



The slight knowledge which we possess at present respecting the 

 details of the natural history of St. Helena prevents our asserting with 

 confidence that these forms are extinct. A small collection of existing 

 shells brought from this locality by my friend and pupil Mr. Edward 

 Alexander affords some additional means of comparison. The same 

 gentleman procured some subfossil forms hitherto unobserved, and 

 one or two others have been brought home by Mr. Blofeld. 



I take this opportunity of placing these on record, with a remark 

 on the indications they afford of the ancient geographical relations of 

 the island in which they occur. 



The so-called *' subfossil " St. Helena shells with which I am ac- 

 quainted are five species of Bulimus, one of Achatina, one or two of 

 Helix, and one of Succinea. The existing indigenous land-shells of 

 St. Helena are five species of Bulimus, two Achatince, three Helices, 

 and two species of Succinea. 



Of the five subfossil Bulimi, the affinities of two are decidedly and 

 remarkably South American. The Bulimus auris-vulpina is unlike 

 any Old World form, and its relations must be sought for in the 

 Brazilian B. bilabiatus, and probably B. melanostoma and its allies. 

 For allies of the equally peculiar Bulimus Darvinianus we must also 

 go to Brazil and compare with B. goniostoma and similar types. Of 

 the other two, the affinities are with species now living in St. Helena. 

 Bulimus Sealeianus is nearly allied to Bulimus Helena of Beeve (not 

 of Quoy) and the Achatina exulata of Benson. Cochligena fossilis 

 of Sowerby is allied to this, but very distinct. Bulimus Blofeldi is 

 nearly allied to an existing undescribed species found by Mr. Alexan- 

 der feeding on the cabbage-trees only on the highest points of the 

 island. The affinities of the latter are decidedly West- African ; those 

 of the former point in two directions, African and South American, 

 the latter character possibly prevailing. 



An Achatina, called Cochlicopa subplicata by Mr. Sowerby, is 

 chiefly connected with West Indian forms, but has also relations on 

 the west coast of Africa, such as the A. clavata of Sierra Leone. 



