394 POLYPI. 
ORDER III. 
CORALLIFERI(1). 
The Coralliferi constitute that numerous suite of species 
which were long considered as marine plants, and of which 
the individuals are in fact united in great numbers to consti- 
tute compound animals, mostly fixed like plants, either form- 
ing a stem or simple expansions, by means of a solid internal 
substance. ‘The individual animals, more or less analogous to 
the Actinie or Hydre, are all connected by a common body, 
and are nourished in common, so that what is eaten by one 
goes to the nutrition of the general body, and of all the other 
Polypi. Their volition is even in common, at least it is cer- 
tainly so in the free species, such as the Pennatule, which are 
seen swimming by the contractions of their stems, and the 
combined motions of their Polypi. 
The name of Polypiers has been given to the common parts 
of these compound animals; they are always formed by de- 
position, and in layers like the ivory of teeth, but are some- 
times on the surface, and sometimes in the interior of the 
compound animal. ‘This difference of position has given rise 
to the following families. 
FAMILY I. 
TUBULARII. 
Those of the first inhabit tubes of which the common gela- 
(1) The Poryres a Poryrrers of ourauthor. Here is another instance of the many 
difficulties I have had to encounter in the course of this work, and of the impro- 
