MOLLUSC A. 
117 
Island, whilst at the same time a pre-existing closer geographical 
relationship between the African and American continents than now 
maintains is dimly indicated. The information we have obtained 
respecting the extinct and existing terrestrial mollusks of this iso- 
lated fragment of land would seem to point in the same direction, 
and assuredly to indicate a closer geographical alliance between St. 
Helena and the west [? east] coasts of South America than now holds.” 
Mr. J. R. Blofeld, F.Gr.S., also records, in reference to the con- 
ditions under which he found these subfossil shells of St. Helena, 
about half a mile behind Longwood, at an elevation of about 1700 
feet above the sea, on a hill-side worn into numerous clefts or ravines 
by the heavy rains, as follows :* — “ The shells are met with in 
■various elevated parts of the Island. The surface of the hill to a 
depth of five to six feet consists of dark mould, and under this is a 
stratum of a greyish- brown friable earth about three to four feet 
thick ; in this latter bed the shells occur. f This earth also contains 
bird-bones,] perfect and fragmentary, in abundance; and it was 
suggested that possibly in some cases the shells may have been 
brought to the spot by birds that fed on their living occupants. 
“ The B. auris-vulpina is accompanied by B. subjolicata and Helix 
bilamellata. In the ‘shell-bed’ are found numerous lumps of 
several sizes, composed of a white powdery substance, and associated 
with a harder yellow substance. § Some specimens of a new species 
°f Bdimus [B. blofeldi, E. Forbes) were found (together with some 
young- Helix bilamellata) in a reddish clay or loam on the side of a 
* Proceed. Geol. Soc., March 10, 1852, p. 195. 
t “ This deposit is composed chiefly of vegetable matter and carbonate of lime. The 
batter is present, both in the form of prismatic crystals (shell tissue ?) and as the coating of 
vegetable fibres. The majority of the specimens of IS. auris-vuLpina presented to the Geo- 
lo gical Society’s Museum by the late Mr. Seale, F.G.S., wore embedded in a whitish coherent 
sa nd, consisting of grains (chiefly inorganic) coated witli calcareous matter.” 
X “ Professor Owen, having examined these bones, pronounces them to belong to marine 
'™ s - The Professor has also examined some specimens of similar bones from Turk’s Cap 
St. Helena, presented to the Geological Society by Captain Wilkes, It.N. These also are 
a bones of marine birds, most of them being of the Petrel kind ; some of them belong to the 
^ubgenus Pujfinw. The bones from Turk’s Cap Bay are from a greyish-brown” earthy 
e P°sit, containing much inorganic sand, the grains of which are partially coated with 
calcareous matter.” 
^ § “ This white substance has been chemically examined by Dr. Percy, F.G.S., who 
serves, that it consists of matter soluble in nitric acid with effervescence, with the exception 
® Sma11 quantity of insoluble residue, probably siliceous. The soluble matter is carbonate 
0 . j me > sulphate of lime, carbonate of magnesia, and phosphoric acid in combination with s?squi- 
C * 1 °c Ir ° U ' The h;uv *or yellow portion was found to contain organic matter, possibly the 
‘ lu ' e °‘ bhe yellow colour, aud to be similar in constitution with the white powder.” 
