Ill 
lions, as analogous to the stems of Antipathes, room xl 
or Black Coral, and therefore the axis of zoo¬ 
phytes ; and have fancied that, when alive, they 
were covered like the Antipathes, with an eva¬ 
nescent bark, in which they supposed the po¬ 
lypes which formed them to be situated. But 
recent observations on sponges in their living 
state have not verified this theory; for they 
have been found to be entirely destitute of any 
polypes, but to be living masses, covered with a 
gelatinous coat, and absorbing water through 
the small pores spread over its surface, and 
emitting it by the larger scattered holes called 
oscula; and that though the fibres of many of 
the sponges greatly resemble the axes of Gor - 
gonice , in their chemical composition and or¬ 
ganic structure, they nevertheless cannot be 
confidently pronounced to belong to the ani¬ 
mal, rather than to the vegetable kingdom. 
The sponges have been divided into several 
genera, according to the structure of the ske¬ 
leton. 
In the common sponge (Spongia) the body 
is very elastic, composed of horny fibres anas¬ 
tomosing in every direction, w ; hile in the Calcio- 
spongici the body is harder, rather elastic, com¬ 
posed of subcartilaginous fibres, and supported 
by stellate, calcareous spicula. The Halina , or 
Flinty Sponges, are rigid and friable, composed 
of 
