MO 
NATURAL HISTORY. [NEW BUILDING. 
three orders, the Zoanthiaria , Zoophytaria , (p. 142,) and 
Polypiaria , (p. 145). 
The first order of these animals, or Zoanthiaria, 
(Cases 1 to 20,) are so called from their resembling a 
flower when their tentacles are expanded: they are cha¬ 
racterized by having very numerous simple tentacles 
placed in one or more series round their mouth, and their 
stomach furnished with more or less numerous longi¬ 
tudinal folds, which subdivide it into different cells. 
Some of these, as the Sea Anemonies, (Actiniadee,) 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 Zoanthidee (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 
the animal which, by the growth of new parts, are no 
longer wanted for its nourishment, and in this manner 
they form a hard and stony case, amongst the folds of 
which they can contract themselves, so as to be pro¬ 
tected from external injury, and by the same means to 
form for themselves a permanent attachment, which pre¬ 
vents their being tossed about by every wave of the ele¬ 
ment in which they live. The stony substances so formed 
are called Corals , and their mode of formation causes 
them exactly to represent the animal which secretes 
them ; the upper surface is always furnished with radiat¬ 
ing plates, the remains of the calcareous particles which 
were deposited in the longitudinal folds of the stomach 
before referred to, and as these plates do not usually 
reach to the centre, there is almost always a vacant space 
in the middle between them. 
The structure of these animals, and of the corals they 
form, is most easily studied in those kinds which are 
