109 
by variously disposed calcareous or siliceous RQOM XI 
needle-like spines. 
In the first division of these the coral is co¬ 
vered with a smooth fleshy bark, in which are im¬ 
mersed eight-sided cells. This division contains 
the genera Lobularia , characterized by the coral 
being branchy and soft, and the internal part 
scattered with small spicula; and Cydonium , in 
which the bark is hard, and the centre of the 
coral almost entirely formed of large radiating 
spicula. In the other division, containing the 
genus Zenia , the coral is light and cellular, 
especially in the dry state, and the outer sur¬ 
face of the stem is scattered with small spicula, 
which are crowded together, and form a tuft 
round the mouths of the cells, which are placed 
at the tips of the branches, giving the coral 
much the appearance of the Sea-Pens, from 
which they differ in being attached and irregu¬ 
larly branchy. 
The last family of this order are the Sea-Pens 
(P enncitulidce), which are peculiar for not being 
attached by a dilated base, like the other corals, 
but free, living partly imbedded in the sand on 
the sea-coast. They have often been called 
Swimming Corals, but it is now generally be¬ 
lieved that they never willingly leave their si¬ 
tuation in the sand. They are all brilliantly 
phosphorescent. Their main stem is simple, 
subcylindrical, and fleshy, supported by a linear, 
fusiform, 
