77 
In others (Isis and Melitea ) the axis is equally calca¬ 
reous, but jointed, and in the first the internodes, or parts 
between the joints, are solid, and the joints cartilaginous, 
whilst in the latter the internodes are fibrous, and the 
knots are spongy and swoln. The knots at the base 
of the axis of these genera, and especially of the Horse¬ 
tail Coral, become obliterated in old age, when they 
are covered by a calcareous coat. 
The Gorgoniae are easily known by the axis being 
horny and continuous, and the bark is persistent. In 
most of these the cells of the animals are even with the 
surface, as the double-edged Sea-Fan (Gorgonia an - 
ceps ); in others, as the common Sea Fan (Gorgonia 
Jlabellum ), the cells are slightly prominent. The Eu¬ 
nice® only differ from the Gorgoniae by the cells being 
cup-shaped and prominent, the bark thicker, and the 
axis more slender and tubular. The Plexaurae have 
the same thick bark as the Euniceae, but the cells 
are immersed. The Muriceae and Primnoae have a 
rather thinner bark and prominent cells, covered with 
scales. 
The Antipathes have an axis like that of the Gor¬ 
goniae, but it is covered with minute spines so as to 
be rough to the touch, and in a living state with a thick 
gelatinous bark, as may be seen in one of the speci¬ 
mens, in which the polypes are immersed; but both the 
polypes and the bark are deciduous. 
The family of Alcyonia ( Alcyoniadce ), are very like 
the Gorgoniae and the true Corals in the form of their 
polypes, which live in cells sunk into a fleshy bark, 
attached to marine bodies by a dilated base ; but they 
are without any distinct axis, and are strengthened by 
variously disposed calcareous or siliceous needle-like 
spines. 
In the first division of these the coral is covered with 
a smooth fleshy bark, in which are immersed eight¬ 
sided cells. This division contains the Lobulariae, 
characterized by the coral being branchy and soft, 
and the internal part scattered with small spicula; and 
the 
ROOM XL 
Nat. Hist. 
