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CLASS III. — ORDER II. 
Gorgonias of the two last sections, whose polypi ap- 
pear in small papillous risings or tubercles, nor with 
the first, whose very thin rind almost wholly dissolves 
in acids, whilst that of the Plexauras scarcely effer- 
vesces with them : in short, the nature of the fleshy 
envelope, its great thickness, the stiffness of the 
branches, their form, and the largeness of the polypi, 
which never project, and still more the existence of 
real cells, will always distinguish the Plexauras from 
others of the Gorgonian order. 
In these Polypidoms is found a membrano-granu- 
lous substance, of the colour of violet, which ap- 
pears to unite the rind with the axe, and adheres to 
these two parts, or sometimes to one alone, or first 
to one and then to the other ; its thickness is not 
considerable ; the internal part is slightly striated ; 
the external surface is marked with numerous deep 
furrows, longitudinal and parallel. This membrane 
is in all probability of great importance during 
the existence of the animal ; it is scarcely apparent 
in the Gorgonias; it visibly exists in the Isidias, 
and also in the Corallinas. It is perhaps destined 
to connect the myriads of animalcula which com- 
pose the swarms inhabiting the deep, and to effect a 
mutual communication between these singular beings, 
every individual of which seems to enjoy a peculiar 
life, whilst the mass is endued with a general exist- 
ence independent of that of the individuals : or it 
may be destined to supply the increase of the inte- 
rior, by adding new layers to the axe that sustains 
the fleshy envelope or rind ; its adherence to both the 
envelope and the axe renders this hypothesis not im- 
probable, particularly as the cells do not penetrate so 
deeply through the fleshy rind. 
