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 Ace- 

 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- 



