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tie resembling any known animal substance should be allowed a place 
in this part of a work, will not, by many, be readily admitted. By 
those, however, who are aware of the vast variety of forms which this 
animal matter assumes, the probability of its having been the origin 
of this fossil will not, I trust, be denied. 
I have some reasons for supposing that the termination of this sub- 
stance is in small and very numerous ramifications ; and that these ra- 
mifications occasion the small tubuli and foramina perceived in cer- 
tain pebbles which are frequently found among the gravel. To these 
terminations of this fossil, I also attribute the light-coloured ramifying 
* veins, observable on the fractured surfaces of some pebbles : the vacui- 
ties which those pebbles originally acquired, by having been formed 
on those ramifications being filled up by subsequently added sili- 
cious matter. These, however, are conjectures too little supported by 
observation to be insisted upon. 
Not less problematical than that of the last is the origin of the 
fossil Plate X. Fig. 12. The one which is here figured was formerly 
in the collection of Mr. Strange. These fossils are formed of chalk, 
and generally have somewhat of a conical figure, the apex of the cone 
being rather rounded. The surface is very closely beset with small 
depressions, pretty regularly disposed in somewhat of a quincunx or- 
der. From cursory observation I had been led to suppose this fossil to 
have owed its origin to either a flustra or millepore : but, on close in- 
spection, especially with a glass, I found reason to dispose it among 
the alcyonia. That it was not a flustra I concluded from being able, 
as I imagine, to trace its organization to some depth into the chalk : 
and that it was not a millepore I was satisfied, from perceiving that, 
Avith the glass, the substance interposed between the pores had every 
appearance of alcyonic or spongeous structure. I have since obtained 
a similar fossil by the kindness of Mr. Cunnington, from the chalk- 
pits of the northern parts of Wiltshire. 
There is no one among the fossil zoophytes which displays a more 
VOL. II. Q 
