90 
portunity of fair comparison could be found, between the recent and 
fossil alcyonia. 
This, however, is very far from being the case : and indeed when we 
reflect on the transmutation which has taken place ; that a soft, gela- 
tinous, or spongy substance, has become a hard and ponderous stone, 
we cannot but be affected with a high degree of astonishment ; especially 
on perceiving that this great and extraordinary change of substance 
has been accompanied by so little change of form. In consequence 
of this I trust I shall be able to place before you many bodies, even 
in a silicified state, which will immediately appear to have been 
animals of this description, belonging to a former world. So great 
indeed will be the variety of these bodies, and so perfectly well preserved 
will they appear, as to render it necessary for me to say a few words, 
respecting the state of preservation in which they are found. 
This is rendered necessary; since the comparatively frequent ap- 
pearance of these bodies, in a fossil state, appears to contradict a 
position laid down in the former volume, whilst speaking of fruits, that 
substances possessing a pulpy consistence were not likely to be found 
in a fossil state ; since their decomposition would most probably take 
place with too much rapidity to allow of that change being effected, 
on which their mineralization would depend. But a peculiarity of 
structure exists in these animals, which exempts them from the in- 
fluence of this law. It appears, as we have seen from the observations 
of Marsilli and Donati, that these animals have blended, with their 
gelatinous and carneous substance, innumerable minute spiculie, which 
may be considered as tbe bones of tbe animal. These manifest them- 
selves by the prickling sensation they occasion, on being handled, 
which has obtained for some of these animals the name of the sea- 
nettle. That these spiculse, formed of a hard and durable matter 
may, in some, and especially that the spongy fibres and coriaceous 
covering may, in others, keep up the form of the animal, for a sufficient 
time to admit of the petrifactive process being accomplished, seems 
