66 NATURAL HISTORY. Qn. ZOOL. GAL. 
the society is composed to procure a fair and equal share of 
nourishment from the water which surrounds them, and 
on which they live, as the leaves of trees extract nou¬ 
rishment from the air in which the plant grows. 
Each individual animal of these zoophytes has a simple 
plaited membranaceous bag-like stomach, with only a 
single orifice, like that of the Star-fish, and their mouth is 
surrounded by a more or less numerous series of tentacles, 
which search for and conduct the food that comes within 
their reach into the digestive cavity, while the animal 
itself is generally attached by its back to marine bodies, 
and very commonly to others of its own kind ; the union 
which they form with each other is sometimes so intimate 
that one individual cannot be injured without its being 
felt by the whole society. The hard parts of these 
animals have been all classed under the name of Corals, 
but the animals which form them are of three very dif¬ 
ferent kinds, each forming a peculiar kind of skeleton for 
its protection. 
The first kind of these animals, or Zoanthiaria, 
(Cases 1 to 20,) are so called from their resembling a flower 
when their tentacles are expanded: they are characterized 
by having very numerous simple tentacles placed in one 
or more series round their mouth, and their stomach fur¬ 
nished with more or less numerous longitudinal folds, 
which subdivide it into different cells. 
Some of these, as the Sea Anemonies, ( Actiniadce ,) are 
quite soft and covered with a smooth skin, so that they 
can only be preserved in a damp state. The Lucernarice 
only differ from these in the mouth being cut into 4 or 8 
lobes. A few have a hard cartilaginous outer skin, 
which is often strengthened by the deposition of earthy 
grains within its surface, as the Zoanthidce (Casel). 
Some of these are crowded together into a mass, as 
Corticifera; others are distinct from one another, but 
arise from a common surface, which is either an ex¬ 
panded base, as in Mammillifera , or a creeping stem as 
in Zoanthus. By far the greater number of these ani¬ 
mals, as they grow, deposit in the cellular substance 
of the flesh of their back an immense quantity of earthy 
matter, which enlarges as the animal increases in size, 
and in fact fills up all those portions of the substance of 
