514 CLASS ECHINODERMATA. 
in its divers parts, by means of fibrous layers which enter 
into its composition. Its axis enclosesa simple stony stem. 
The polypi have generally eight denticulated arms. Most of 
the species shed a lively phosphoric light. 
Whatever may be the general form of the pennatule, they 
have always one of their extremities without polypi. This 
has been compared to the tubular part of the feathers of birds. 
PENNATULA, (properly so called) Cwv., 
Which, having given their name to the whole genus, have them- 
selves derived it from their resemblance to a quill. The part 
without polypi is cylindrical and terminated in a blunt point. 
The other part is furnished on each side with wings, or barbs, 
more or less long, and broad, supported by spines, or stiff 
sete, which spring from their interior, and bristle one of their 
edges, without, however, being articulated with the petrous 
stem of the axis. It is from the centre of these barbs that the 
polypi issue forth. 
The Ocean and the Mediterranean both produce 
Pennat. rubra, et Penn. phosphorea, Gm., Albinus Annot. 
Acad, i. vi. 3—4. Which has the stem between the barbs 
very rough behind, except on a line which traverses its 
length. 
We find more particularly in the Mediterranean, 
Pennatula grisea, Gm., Albinus, Annot. Acad. 1, 2. larger, 
with broader barbs, more spiny, and a smooth stem. 
VIRGULARIA, Lam., 
Differ from the pennatule, only because their wings, much 
shorter in proportion to their total length, are deprived of 
spines. (Pennatula mirabilis, Mill., Zool., Dan. xi., very. 
different from the true Pen. mirabilis of Linneus.) 
These wings sometimes represent only simple transverse 
ranges of tubercles. (Pennat. juncea, Pall. et Gm.) 
