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red colour, where it is not invested with its cortical part, which is of 
a grey colour, pervaded by a slight tinge of red, is represented Plate IX. 
Fig. 8. The pedicle and the opening at the superior part are here 
very perfect. Slight traces of lines, passing from the pedicle to the 
opening, are discoverable on this specimen, and doubtlessly point out 
the arrangement of fibres, by which the animal was enabled to draw in 
and eject the water which supplied it with food. This fossil, I have 
reason to believe, is English. 
The set of fossils, which I shall next place before you, is, in many 
respects, extremely interesting. In the general outline of their form, 
many of them so much resemble the fossils last described, as, at first 
sight, to lead to the supposition that they are only varieties of the 
same species ; but, on a closer investigation, several circumstances are 
observed, which seem to warrant a contrary opinion. 
The following are the most remarkable circumstances, in which these 
fossils differ from the former. First, They appear to be almost entirely 
silicious. Secondly, In that part of the fossil, in which an opening 
existed in the former species, a rather prominent substance is found. 
Thirdly, Instead of the finely granulated surface possessed by the 
former, which appears to have been produced by innumerable minute 
openings, passing into the substance, the surface is, in the latter, such 
as might be expected to result from the instillation of lapidifying 
matter, into a substance of spongeous texture, embraced by numerous 
ramifying filaments. Fourthly, An entire difference in their internal 
organization. 
One of these fossils is represented, Plate IX. Fig. 12, with its 
longitudinal section, displaying its internal organization. The general 
figure of this fossil approaches very nearly to that of the fossil last 
described ; or , perhaps, it may be considered as bearing a nearer re- 
semblance to a fig. Its spongy alcyonic texture is observable, not only 
on its polished internal, but on its rough external surface ; and like 
the preceding fossils, it appears to have terminated at its lower end in 
a gradually diminishing pedicle. At the centre of the superior part, 
VOL. II. 
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