308 
INCRUSTATIONS ON PLANTS. 
minuted shell and sand: if this be the fact, their explanation is 
obvious. 
Other appearances of somewhat more difficult explanation were 
discovered and pointed out to me by Captain Maxwell near Simon’s 
Town. Somewhat to the eastward of the town is a large bank, 
which rises from the sea to the height probably of a hundred feet, 
and seems to have been formed by an accumulation of shell and 
sand brought up by the south-east wind. That such is the origin 
of the bank, is probable from its being exposed to the direct influ- 
ence of this wind, and from its very loose structure. I at first 
thought it possible that it might have resulted from the decom- 
position of sandstone ; but relinquished this opinion on finding 
the fragments of shell extending much below the surface. On 
this bank a great number of calcareous cylindrical bodies lie scat- 
tered about, and at first sight resemble the bones of animals bleached 
and disorganized by exposure to the air. On a closer examination 
many of them are found to be branched ; and others are discovered 
rising through the soil, and ramifying from a stem beneath thicker 
than themselves. Their vegetable origin immediately suggests 
itself, and is confirmed by a further enquiry. They are seldom 
solid, their centres being either hollow or filled with a blackish 
granular substance, which in many specimens, except in colour, 
much resembles the substance called roastone by mineralogists. 
Their outer crust is chiefly composed of a large proportion of 
sand, and a small proportion of calcareous matter, and in many 
specimens contains fragments of ironstone, and quartz an inch 
square. That they are really incrustations formed on vegetables 
which have afterwards decayed, is proved by the different degrees 
of change which the internal parts of different specimens have 
undergone. In some the organization of the plant sufficiently 
remains to leave its nature unequivocal, and near the sea the very 
commencement of the process of incrustation may be witnessed on 
the large Fuel which strew the shore. 
