Ill 
The edge of the upper part, or that which forms the base of the cone, 
is either pierced with several holes, or else is marked with traces of 
holes, which are now filled up with flint. The lower termination, 
which forms the apex of the cone, is also either pierced with one, and 
sometimes with two holes, or bears marks which shew that such openings 
have existed, but have been since filled up by silicious matter. The 
specimen. Fig, 15, will give a tolerably correct idea of the general 
appearance of these fossils. 
Anxious to obtain what knowledge I was able respecting the formation 
of these pebbles, I broke many of them in different directions, and 
was thereby enabled to ascertain that their shape and their openings 
depended on the figure of a body, which they contained in a cavity 
in their central part. This was, of course, seen with more distinctness 
in those which, as in Fig. l6, had been broken in a perpendicular 
direction. 
By the aid of the opening made by fracture, Fig. 16, some of the 
remains of this body will be seen. It will be there perceived, that it 
is formed by a congeries of tuberculated tortuous filaments, which, by 
intertwining with each other, form, in the apex of the cone, which I 
presume to have been the inferior part of this body, a closely reticulated 
columniform body, which, after having proceeded less than an inch, 
appears to have separated into about a dozen ramifications formed 
in a similar manner. At the superior part, on the side, a portion is 
still adherent, in which the original characteristic forms of the ramifica- 
tions of this body may still be seen, bearing a slight resemblance to 
the formation of the fan sponge. 
That this body has derived its origin from some lost species of alcyo- 
ninm or of sponge, I am firmly of opinion ; and trust that in this opinion 
I shall be joined by those who are acquainted with the characters 
of these two genera. Positive evidence will not be obtained until 
the nature and form of this body is ascertained in some more 
perfect specimens,; the difficulty of procuring which is considerable, 
