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CLASS I\ T . 
ALCYONIUM. 
Polypidoms of various shapes, having the appear- 
ance of a thick, porous, or cellular mass, spread out or 
ramified, sometimes lobed, and at others in the form 
of a crust ; the interior substance spongy or corky, 
surrounded by a radiated, tubulous tegument, and en- 
closed in a hard leathery rind. 
The cells of this Polypidom are round, and une- 
qual in their diameters, from four to five milleme- 
tres in depth, separated from each other by thin 
partitions, which are rendered opaque by a vast 
quantity of solid globules, that appear to form the 
least animated part of the zoophyte. These cells en- 
close a polypus, externally composed of a transparent 
sack or membrane ; which is fortified by eight fili- 
form longitudinal fibrous bands, placed at equal dis- 
tances, and difficult to be perceived owing to the 
presence of numerous transverse and parallel fibres. 
The longitudinal fibres seem attached to the bor- 
ders of the cells, and to the roots of the tentacula. 
The sack (which is capable of extending and con- 
tracting, the upper part falling back when the little 
animal retires within its transparent covering) en- 
closes the body of the polypus, having in the centre 
a hemispheric mass, divided into eight equal parts 
by vertical partitions, whose summits present a 
round or lozenge-shaped opening, at the will of the 
