70 
CLASS T— ORDER IL 
NEMERTESIA. 
Plant-lire and horny; garnished through its 
whole extent with small polypiferous oils, curved to- 
wards the stem, and verticillated ; cells placed on the 
inner part of the cil. 
The Nemertesias, not numerous in their species, 
are distinguished from the Sertularias, with which 
they have hitherto been classed, by a variety of cha- 
racters that belong to them exclusively, and which 
do not allow us to confound them with any of the 
genera which compose that Order. 
These Polypidoms are sometimes branching, some- 
times not branching ; in the latter case, their general 
appearance resembles a mouse's tail ; in the first case, 
they cannot be compared to any thing, their aspect is 
peculiarly their own. 
Their cells are invisible to the naked eye, bare, 
and always placed on the interior part of the cils, a 
single one at each articulation. 
The numerous ovaria are axillary to the cils and 
stem. 
The substance of the Nemertesias is membranous, 
horny, and very flexible ; they become almost trans- 
parent by desiccation. 
Their colour, when first taken from the sea, is a 
beautiful citron-yellow, sometimes orange; they be- 
come dull and whitish when exposed to the air and 
light. 
Their height varies from two to five decimetres. 
The Nemertesias are never parasites on marine 
