196 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 10, 



Bulimi, Succinece, and Helices'^ are found in the superficial soils of 

 the islandf . The Bulimus auris-vulpina is not now found in a living 

 state. The shells are met with in various elevated parts of the island. 

 The specimens accompanying this communication were found by the 

 author about half a mile behind Longwood, at an elevation of about 

 1 700 feet above the level of the sea, on a hill-side which is worn into 

 numerous clefts or ravines by the heavy rains. The surface of the 

 hill to a depth of 5 to 6 feet consists of dark mould, and under this 

 is a stratum of a greyish-brown friable earth about 3 to 4 feet thick ; 

 in this latter bed the shells occur J. This earth also contains bird- 

 bones §, perfect and fragmentary, in abundance ; and it was suggested 

 by the author, 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. subplicata and Helix 

 hilamellata. In the " shell-bed" are found numerous lumps of se- 

 veral sizes, composed of a white powdery substance, and associated 

 with a harder yellow substance jj. Some specimens of a new species 

 of Bulimus (B. Blofeldi, E. Forbes), collected by the author, also 

 accompanied this paper. These were found (together with some 

 young Helix hilamellata) in a reddish clay or loam on the side of a 

 hill overlooking the "Briars" in the cutting of the road from James 

 Town to Longwood, about 1200 feet above the sea-level, and about 

 two miles in a direct line from the spot where the larger Bulimi were 

 found. 



* Detailed descriptions and figures of these shells are given by Prof. E. Forbes 

 in the next following communication. 



t For a detailed description of the Geology of St. Helena, see Darwin's * Vol- 

 canic Islands,' pp. 73 et seq. 



X This deposit is composed chiefly of vegetable matter and carbonate of lime. 

 The latter is present, both in the form of prismatic crystals (shell-tissue?), and 

 as the coating of vegetable fibres. The majority of the specimens of B. auris-vul- 

 pina presented to the Geological Society's Museum by the late Mr. Scale, F.G.S., 

 were imbedded in a whitish coherent sand, consisting of grains (chiefly inorganic) 

 coated with calcareous matter. 



§ Prof. Owen, having examined these bones, pronounces them to belong to 

 marine birds. The Professor has also examined some specimens of similar bones 

 from Turk's Cap Bay, St. Helena, presented to the Geological Society by Captain 

 Wilkes, R.N. ; these also are all bones of marine birds, most of them being of the 

 Petrel kind ; some of them belong to the subgenus Pujffinus. The bones from 

 Turk's Cap Bay are from a greyish-brown earthy deposit, containing much inor- 

 ganic sand, the grains of which are partially coated with calcareous matter. 



Ij This white substance has been chemically examined by Dr. Percy, F.G.S., who 

 observes, that it consists of matter soluble in nitric acid vrith effervescence, with 

 the exception of a small quantity of insoluble residue, probably siliceous. The 

 soluble matter is carbonate of lime, sulphate of lime, carbonate of magnesia, and 

 phosphoric acid in combination with sesquioxide of iron. The harder yellow por- 

 tion was found to contain organic matter, possibly the cause of the yellow colour, 

 and to be similar in constitution with the white powder. 



This substance may possibly be the same as that referred to by Mr. Darwin in 

 the footnote at page 87, ' Volcanic Islands.' Under the microscope much prismatic 

 matter is visible, which might readily be taken for the carbonate of Ume hberated 

 from the prismatic cells of shell-tissue ; but, as this withstands to some extent the 

 action of nitric acid, it would appear to be sulphate of Ume. 



