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reticulated and the finer fasciculated kinds, which seem to partake of 
both sorts. 
In the substances considered as alcyonia by Donati, as well as in 
some of those which have been described by Count Marsilli, similar 
large bundles of elastic fibres like needles were discovered. These had 
been reckoned alcyonia by most authors, but in Mr. Ellis’s opinion 
they should not be so reckoned, since neither Donati nor Marsilli 
mention any polype suckers extending out of their pores ; he considering 
the existence of these as the distinguishing character of the genus 
alcyonium, as much as the pores without the polypes in these elastic 
fibrous bodies is the character of the sponges.* 
It is evident that these needle-like spiculae cannot be considered as 
belonging to the genus spongia only ; since among the alcyonia some 
are admitted to be formed of a spongy substance, into the composition 
of which these spicules may of course be expected to enter: on the 
presence or absence therefore of polypes in the cells of the substance 
must alone depend the necessary distinction. 
But when the difficulty of distinguishing between the alcyonia and 
the sponges, even in a recent state, is considered, the oryctologist will 
easily find an excuse for his inability, to make a similar distinction 
between these substances, after they have undergone the lapidifying 
process : when their pores have become filled ; and their colour and 
their substance, and, in fact, their whole nature has been changed. 
Indeed, the assumed generic difference between the alcyonia and 
sponges is such as must be entirely lost in most of these substances 
which have undergone the change of petrifaction. Whether the pores, 
which are discoverable in a fossil, were the dwellings of the polypous 
hydrae or not, can no longer be ascertained ; since their radiation, 
which is supposed to characterize the openings in which these minute 
animals exist, and which is frequently so faint in the recent alcyonium 
* The Natural History of Zoophytes, &c. P. 183. 
