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being filled with the grey flint, a longitudinal section, which would 
pass through that part, would give a cordlform or cyathiform figure, 
from this dipping of the matter of grey flint, into the middle of the 
substance of the alcyonium : and if the alcyonium was formed with a 
broad base, similar to that which is observable in the specimen, Plate IX. 
Fig. 4, the appearance yielded by its longitudinal section would perfectly 
accord with the figure of the inclosed fossil, Plate XI. Fig. 4. The 
colour of this fossil next excited my consideration, doubting how far 
this instance would authorize the attributing of this colour, even to other 
alcyonia of the same species ; but on looking over my collection of these 
fossils, I found the detached ficoid fossil, purposely introduced, Plate IX. 
Fig. 8, which exactly agreed in its form with that which in this specimen 
is involved in the flint. Not only is the red colour very evident in 
the body of this detached fossil, but it still retains, over great part 
of its surface, a thin white covering, apparently the remains of a 
similar coat, with that which is seen to surround the alcyonium 
contained in the flint. It is hardly necessary to remark, that the red 
colour of the animal, blended with the dark semidiaphanous flint, will 
perfectly account for the purple hue so frequently observable in these 
specimens. 
The flint stone, Plate XII. Fig. 5, found on the sea-shore, at Southend, 
in Essex, had often engaged my attention. The curious contexture of 
the plexus of tubuli, of which it is chiefly composed, led me, at first, 
to suppose it to be a mass of minute serpulae ; this opinion was, however, 
soon corrected, on discovering, by means of a lens, the frequent inoscu- 
lations of these tubuli. I became then suspicious of its alcyonic nature; 
and after having attended to the alcyonic flints just examined, was 
convinced that it owed its form to a substance of this kind : the circular 
mark of its original cortical investing matter, yielding the most corro- 
borating proof that this opinion was correct. 
Just before the plate which this chapter refers to was engraved, 
the son of that ingenious artist, Mr. Springsguth, to whose labours this 
