550 
PENNATULA, 
This genus of animals differs remarkably from all the 
other zoophytes by their fwimming freely about in the 
fea, and many of them having a mufctilar motion as they 
fwim along. They have no opening at the bottom as 
was formerly thought, nor any other paffage but through 
their polype mouths; by thefe they take in their food, 
and through thefe they produce their eggs, as in moll 
zoophytes. When we compare them with the other zoo¬ 
phytes, they approach nearelt to the Gorgonia, as having 
a bone in the inlide like them, which is covered with 
ffefli, and their upper parts full of polype-like mouths. 
1. Pennatula coccinea, the fcarlet fea-pen : ftem round, 
radiating, with papillous polype-bearing fides, and cla- 
vate at tlie top. It inhabits the deeps of the White Sea, 
and unites the two genera, Alcyonium and Pennatula; 
it is loft, red, an inch and half high, and as thick as 
the little finger; it is wrinkled, with the papillae difpofed 
in rows. 
2. Pennatula grifea, the thorny fea-pen : ftem flelhy, 
with a fmooth midrib and imbricate plaited fpinous ra¬ 
mifications. It is found in the Adriatic, and is about 
eight inches long; it ftiines by night; back of the mid¬ 
rib lanceolate, fmoothilh; rays imbricate, and undulate 
on the anterior margin, the lobules are armed with a 
fpine, and obtufely crenate at the margin. 
3. Pennatula phofphorea, the Britifh fea-pen : ftem 
flelhy, with a rough midrib and imbricate ramifications. 
It is about four inches long, and red. Dr. Solander calls 
it the Britifh fea-pen, to diftinguilh it from the rubra, 
which he calls the Italian fea-pen, and becaufeit is found 
in great plenty flicking to the baits on the filhermen’s 
lines round the coafts of this kingdom ; efpecially when 
they make ufe of mufl'els to bait their hooks. Great num¬ 
bers have been taken on the coaft of Scotland, efpecially 
near Aberdeen. 
This animal was well known to the ancients by the name 
of the fea-pen ; many of the old authors took it fora fucus, 
or fea-plant. It has been found in the ocean from the coaft 
of Norway to the moft remote parts of the Mediterranean; 
and not only dragged up in trawls from great depths of 
the fea, but often found floating near the furface. Dr. 
Shaw, in his Hiftory of Algiers, remarks that they afford 
lo great a light in the night to the fifhermen, that they 
can plainly difcover the fifh fwimming about in various 
depths of the fea. The luminous effect is confined to the 
plumule of the quill, or that part which is inhabited by 
the polype. Spallanzani, in a letter to Bonnet, ftates that 
the light is only emitted when the fea-pen is in motion ; 
and that there is a mucous luminous fubftance furnifhed 
by the polype, which is foluble in water, and becomes 
mixed with the fea-water that is admitted into the,pen 
by means of a hole fituated at the extremity of its (talk. 
(Mem. Soc. Ital. tomo ii.) But the exiftence of any hole 
at the extremity is denied by Mr. Ellis, whofe defcrip- 
tion (Phil. Tranf. liii.) is as follows : 
“The outward appearance of this animal is not unlike 
one of the quill-feathers of a bird’s wing; but they are 
found of different fizes, from four to eight inches in 
length; the lower half of it is naked, round, and white, 
not unlike the quill-part of a writing-pen ; the upper part 
reprefents that of the feathered part of the pen, and is of 
a reddifh colour. This upper half, which arifes from the 
quill, and is feathered on both fides, is a little compreffed, 
and becomes fmaller and fmaller till it ends in a point at 
the top; along the back of this, in the fame manner as in 
the inner fide of a common writing-pen, there is a groove 
in the middle, from the quill to the extremity; from each 
fide of this upper part of the ftem proceed little parallel 
feather-like fins ; thefe begin at the top of the quill-part, 
very final) on each fide at firfl, but lengthen as they ad¬ 
vance towards the middle; hence they fhorten gradually 
on each fide, till they end in a point at the top, their 
terminations preferving on each fide the figure of the feg- 
ment of a circle. 
“To come now to confider more minutely thofe pin- 
1 
nulae, or feather-like fins, that projeCt on each fide, and 
form the upper part of this animal. Thefe are evidently 
defigned by nature to move the animal backward or for¬ 
ward in the fea, confequently to do the office of fins, 
while at the fame time, by the appearance of the fuckers 
or mouths furniftied with filaments or claws, they were 
certainly intended to provide food for its fupport; for, 
notwithftanding what Linnaeus has faid in regard to its 
mouth, in his Syftem of Nature, viz. Os bajeos commune 
rotundum , Mr. E. could not, with the help of the beft 
giafl'es, difcover that the point of the bafe was penetrated 
in the leall; fo that he is clearly of opinion, that this ani¬ 
mal, like the Hydra arCtica, or Greenland polype, de- 
fcribed in his Eftay on Corallines, nourifties and lupports 
itfelf by thefe fuckers or polype-like filaments ; that by 
thefe both kinds take in their food, and have no other vi- 
fible means of difcharging the exuviae of the animals they 
feed on, than by the fame way which they take them in ; 
and that, from attentively confidering the ftruCture and 
manner of living of both thefe animals, he clafies them 
in the fame genus of Pennatula, though they vary very 
much in their exterior form and fize, and confequently 
are of very different fpecies. The ftem of the fuckers of 
this animal is of a cylindrical form; from the upper part 
proceed eight fine white filaments or claws, to catch their 
food : when they retreat on the alarm of danger, they 
draw themfelves into their cafes, which are formed like 
the denticles of the corallines, but here each denticle is 
furnifhed with fpiculas, which clofe together round the 
entrance of the denticle, and protect this tender part from 
external injuries.” 
Some of the moil curious remarks of Dr. Bohadfch on 
the anatomy of this animal, as alfo on the appearance of 
it while alive in fea-water, areas follow: “When the 
trunk is opened lengthwife, a faltifh liquor flows out of 
it, fo vifcid as to hang down an inch ; the whole trunk 
of the ftem is hollow; its outward coriaceous membrane 
is more than a line thick, and forms a llrong covering to 
it : between this and another thinner membrane of the 
pinnated part of the trunk, are innumerable little yellow- 
ifli eggs, floating in a whitifh liquor, about the fize of a 
white poppy feed; thefe are beft feen when the trunk is 
cut acrofs ; this thin membrane lines the whole infide of 
the trunk, in which we obferve nothing but a kind of 
yellowifh bone, which takes up three parts of the cavity. 
This bone, in fome of thefe animals, is above two inches 
and a half long, and about half a line thick; in the mid¬ 
dle part of it, it is quadrangular; towards each end it 
grows round and very taper: that end is fmallefl which is 
neareft the top of the pinnated trunk. The whole bone 
is covered with a yellowifh clear fkin, which at each end 
changes into a ligament; one of which is inferted in the 
top of the pinnated trunk, the other in the top of the 
naked trunk; by the help of this upper ligament, the 
end of this little bone is either contracted into a very 
narrow arch, or difpofed into a ftraight line, according to 
the motion of the trunk. The fins likewife are compofed 
of two fkins : the outer one ftrong and leathery, and co¬ 
vered over with an infinite number of crimfon ftreaks, 
the inner fkin is thin and clear : thecylindrical part of the 
fuckers are in the fame manner, only with this difference, 
their outer fkins may be fofter. Both the fins and the 
fuckers are hollow, fo that the cavity of the fuckers may 
communicate with the fins, as their cavity does with the 
trunk. 
“ We now come to the appearance which this animal 
makes when alive in fea-water. The trunk then was 
contracted circularly at the bottom of the naked part of 
the Item, and by this contraction formed a zone of the 
mod intenfe purple, which moved upwards and down¬ 
wards fuccefiively: when it moved upwards through the 
length of the pinnated trunk, it there became paler, and 
at length terminated at the top : the motion being fcarcely 
finifhed, a like zone appeared at the end of the naked 
trunk, which finifhed its motion in the fame manner as 
the 
