112 
CLASS II.— ORDER I. 
NESEA. 
Polypidom in the form of a hair-pencil; stem 
simple, terminated by articulated branches, which are 
cylindrical, dichotomous, and united in a head. 
The Neseas have been classed among the Coral- 
lines by all preceding naturalists ; they however differ 
from the latter in too many circumstances to permit 
our confounding one with the other. Their stems are 
not fistular, like those of the Polyphysa and the A6e- 
tabularia ; nor so compact as those of the Corallines ; 
they are composed of numerous fibres loosely anasto- 
mosised, rather longitudinal than transversal, and con- 
tained in a membranous tube, which is encased in a 
calcareous crust, varying in thickness. These stems are 
always simple, sometimes isolated, and at other times 
consisting of several united together, and adhering so 
firmly that it is difficult to separate without injuring 
them. This adhesion is probably caused by the gela- 
tinous matter which wholly covers these Polypidoms 
in a living state, and which in drying glues together the 
parts where it most abounds. 
The branches which diverge from the extremity 'of 
the stem are always dichotomous, articulated, cylin- 
drical, polypous at the extremities, and bear a strong 
resemblance to the genus Galaxaura. 
Having had no opportunity of seeing the Neseas 
in the plenitude of existence, when they are first 
taken from the sea, I can only presume, from atten- 
tively observing their organisation, that in a living 
state the stem is animated like the mass of the 
Alcyoneas, and susceptible of some obscure move- 
