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upper part, is exceedingly perfect ; and at its lower end, or point, part 
of its pedicle remains, which appears to have been remarkably small. 
Its external surface is marked by very strong alternate risings and 
depressions passing round it. Its texture, on this surface, appears to 
have been very close and without any openings, except the very mi-' 
nute foramina resulting from a spongeous texture, so fine as to ap- 
proach to the membranous, and a few winding openings, apparently 
the labour of some invading insect. The internal surface differs very 
much from the external, being so remarkably smooth and regular as 
to have the appearance of the pile of velvet. On being viewed with 
a lens, it is seen that the villous appearance is produced by the infi- 
nite number of minute openings arranged as close by each other as 
possible over the whole surface. It is of a light brown, or buff colour, 
and appears to have much less silex enter into its composition than in 
that of the two last described fossils. Previously to passing to the 
consideration of the next fossil, I must call your attention to the ob- 
vious difference of structure between these fossils and those which are 
represented Plate VIII. Fig. 5, and Plate XI. Fig. 7, and which possess 
somewhat of a similar form. This circumstance is also observable in the 
fossil we shall next examine. 
This fossil, represented in the frontispiece, was found in Wiltshire, 
and was originally in the collection of the Marquis of Donegal. At 
its inferior termination, several processes are given off, which, though 
broken, have much the appearance of the roots of a vegetable : 
an appearance which is, however, much more similar in another 
specimen. From the union of these, a narrow and nearly cylindrical 
neck is formed, which, gradually enlarging, forms a conical cup-like 
body, the sides of which are about the third of an inch in thickness, 
but become much thinner at their edge. From the root-like pro- 
cesses several fibres or tubuli originate, which, ramifying, pass along 
or penetrate the surface, in a direction tending towards its superior 
part. 
