chitine, without any calcareous matter; externally covered by the common
integument of the capitulum; these valves are placed very near to each
other, close under the orifice, and therefore high up on the capitulum;
the membrane between them is smooth and unwrinkled; they are formed of
two rather acuminated lobes, joining each other at above a right angle;
one lobe (the longer one) stretching nearly transversely across the
capitulum, the other running down parallel to its rostral margin: in
shape and position they resemble the scuta of _Conchoderma aurita_; and
if another lobe had been developed it would have run along the orifice,
and then these valves would have resembled the scuta of _Conchoderma
virgata_. In a specimen with a capitulum 2/10ths of an inch long, the
scuta from point to point were 1/20th of an inch in length.
_Peduncle_, much wrinkled, about one third in diameter of the capitulum,
and shorter than it; at the base it is generally expanded into two or
three finger-like projections. _Length_ of the largest specimen, about
one fourth of an inch. _Colour_, according to A. Costa in the work above
cited, “rufo-flava vittatâ;” but after spirits the whole becomes
uniformly yellowish.
_Filamentary Appendages_, situated beneath the basal articulation of the
first cirrus, on the posterior edge of the usual enlargement;
acuminated, about two thirds of the length of the shorter ramus of the
first cirrus.
_Prosoma_ well developed.
_Mouth._--On each side there are two slight prominences; one under the
mandibles, the other transverse nearer to the adductor muscle.
_Labrum_, placed near the adductor muscle, with the upper part not more
bullate than the lower part; crest with a row of blunt teeth, and many
fine bristles growing chiefly outside the teeth; there are many fine
bristles on the inner or supra-oesophageal fold of the labrum.
_Palpi_ not nearly touching each other, pointing towards the adductor:
much hollowed out on their inner sides, hence narrow and acuminated,
with doubly serrated bristles.
_Mandibles_, with three teeth and the inferior angle ending in a single
sharp spine; whole inferior portion narrow; first tooth as far from the
second, as the latter from the inferior angle; owing to the presence of
short thick spines projecting from the sides of the jaw, the lower edges
of the second and third teeth appear pectinated.
_Maxillæ_, nearly two thirds of the width of the mandibles; beneath the
three larger upper spines there is a considerable notch, and the whole
lower part is very slightly upraised; edge irregular, with obscure
traces of either two projections, or perhaps of four steps.
_Outer Maxillæ_, with bristles in front continuous; exteriorly there is
a slight prominence near each olfactory orifice, with a tuft of long
bristles.
_Cirri_ not much elongated; first pair placed not quite close to the
second; five posterior cirri nearly equal in length; pedicels long, with
irregularly scattered spines,--those on the pedicel of the first cirrus
beautifully and conspicuously feathered. The segments of the three
posterior pair are _not_ very short or broad; very slightly protuberant,
each with a long transverse, crescentic, narrow brush of bristles, which
stand two or three deep in the middle, but on the sides are single:
dorsal tufts long, and in the upper segments the spines are thick and
claw-like. This structure is common to all the cirri. First cirrus with
the rami unequal in length by two segments; from the shortness of the
pedicel, this cirrus is much shorter than the second, but its rami are
about two thirds of the length of those of the second cirrus. Second
cirrus (and in a less degree the third cirrus), with the anterior ramus
a shade broader than the posterior ramus, and rather more thickly
covered with spines than are the three posterior cirri. Fifteen segments
in the sixth cirrus; nine in the longer ramus of the first cirrus.
_Caudal Appendages_, rather longer than the pedicels of the sixth
cirrus, composed of seven cylindrical, tapering segments, each with a
circle of very fine bristles on its summit.
The acoustic (?) sacks are situated some way below the basal
articulations of the first cirrus.
2. ALEPAS PARASITA.
ALEPAS PARASITA. _Sander Rang._ Man. des Mollusq., p. 364, Pl.
viii, fig. 5, 1829.[44]
ANATIFA UNIVALVIS. _Quoy_ et _Gaimard_. Annales des Sciences,
Nat., tom. x, p. 234, 1827, Pl. vii, fig. 8.
---- PARASITA. _Quoy_ et _Gaimard_. Voyage de l’Astrolabe, Pl.
xciii, 1834.
TRITON (ALEPAS) FASCICULATUS. _Lesson._ Voyage de la Coquille.
Mollusc. Pl. xvi, fig. 6, tom. ii, part I, 1830, p. 442.
[44] M. Sander Rang rejects the specific name “_univalvis_,” as
signifying a generic character, and he has been followed in this
by MM. Quoy and Gaimard themselves. This, according to the Rules
of the British Association, would hardly have been a sufficient
reason, but it appears that _A. parasita_, like _A. minuta_, has
a pair of horny scuta or valves; and, therefore, the name
_univalvis_ is too obviously false to be retained. With respect
to the generic name Triton, I fully believe that it was applied
by Linnæus to the cast-off exuviæ of sessile Cirripedes.
_A. aperturâ non prominente, capituli longitudinis 2/3 æquante: scutis
corneis: longitudine totâ ad 2 uncias._
Orifice not protuberant, equalling two thirds of the length of the
capitulum: scuta horny. Total length two inches.
Animal unknown.
Parasitic on Medusæ, Mediterranean and Atlantic Oceans: south
shore of England(?)[45]
I have not seen this species, and have drawn up the above specific
character from the Plates and brief descriptions in the Voyages of the
Coquille and Astrolabe. M. Lesson thinks that his species differs from
that of MM. Quoy and Gaimard; but as the peculiar yellow colour of the
capitulum, general shape, short cirri, habits and range, are all common
to both, I believe that they are identical. There is, however, one
singular difference, namely, that the cirri are coloured bright blue in
the Plate in the Voyage of the Astrolabe, and yellowish in that in the
Voyage of the Coquille: this possibly may have resulted from the drawing
in the latter case having been made from a specimen long kept in
spirits.
M. Lesson says that there are seven pair of cirri, from which I infer
that this species has a pair of long, articulated, caudal appendages: he
asserts that each cirrus has ten segments; the cirri are short and
little curled. M. Lesson remarks, that “deux languettes bifurques
occupent le bas de l’ouverture ovale:” I can hardly doubt but that these
are horny scuta of nearly the same shape as in _A. minuta_. The whole
animal seems to be extremely transparent, and of a “jaune-citron clair.”
MM. Quoy and Gaimard, however, remark, that different specimens vary
from white to yellow. Entire length two inches, of which the capitulum
is fourteen French lines. The peduncle is narrow and short.
[45] See Foot-note, p. 159.
3. ALEPAS CORNUTA. Pl. III, fig. 6.
_A. aperturâ parvâ, leviter prominente: scutis nullis: capitulo
plerumque tribus, parvis, compressis eminentiis secundum carinalem
marginem instructo._
Orifice small, slightly protuberant; capitulum without horny scuta;
generally with three small flattened projections along the carinal
margin.
Outer maxillæ with the inner bristles divided into two groups; segments
of the posterior cirri extremely numerous, each with one pair of main
spines; inner rami of the fifth and sixth cirri rudimentary.
St. Vincent’s, West Indies, attached to an Antipathes, collected
by the Rev. L. Guilding.
_Capitulum_ globular, slightly flattened, smooth, translucent, entirely
destitute of valves; orifice slightly projecting or tubular, parallel to
the longitudinal axis of the peduncle, with the edges sinuous; it
appears more tubular than it really is, from the convexity of the part
of the capitulum immediately beneath the orifice. Three small, flexible,
horny, irregular prominences project from the carinal margin; one at the
bottom of the capitulum; a second about half-way up it; and a third
generally close to the orifice; but their positions vary a little, and
the prominences vary still more in shape and size, being either rounded
and very small, or much flattened and considerably prominent; they are
imperforate; in the membrane under them a few tubuli may be seen, which
are not elsewhere visible; their summits are roughened with very minute
points and beads of chitine; others, still minuter, are scattered over
the whole capitulum.
_Peduncle_ short, narrower than the capitulum, into which it insensibly
blends; strongly wrinkled; surface of attachment wide; position with
respect to the branches of the coralline, various.
_Size and Colour._--The largest specimen, including the peduncle, was
half an inch in length, and 3/10ths of an inch across the capitulum;
colour, after having been long in spirits, brownish-yellow.
_Filamentary Appendages_, one on each side, short, tapering and pointed;
seated on the posterior margin of a slight swelling beneath the basal
articulation of the first cirrus; they are about equal in length to the
pedicels of this cirrus.
The _Mouth_ is directed abdominally; labrum much produced downwards, so
as to be far separated from the adductor muscle; moderately bullate,
forming about one third of the longitudinal axis of the entire mouth;
upper part forming a slightly overhanging prominence; crest with a row
of blunt, bead-like teeth, and externally to them there are numerous
curved short bristles.
_Palpi_ (Pl. X, fig. 8,) unusually narrow, a little hollowed out along
their inner margins; pointing towards the adductor muscle; thickly
covered with doubly serrated bristles.
_Mandibles_, with either two or three teeth; inferior angle narrow and
tooth-like; both sides covered with strong bristles or spines,
projecting beyond the toothed edge.
_Maxillæ_, with two large upper spines, and a third rather distant from
them; beneath these, there is a wide notch or hollow; inferior part
square, projecting, bearing six pair of moderately long spines, (of
which the central one is the longest,) mingled with finer ones.
_Outer Maxillæ_, with a semicircular outline; the serrated bristles in
front are divided into two groups; externally there is a rounded and
very considerable projection covered with long bristles. Olfactory
orifices slightly prominent, approximate, seated within and just beneath
the rounded projections at the base of the maxillæ.
_Body._--Prosoma little developed; thorax small.
_Cirri_, extremely long, but slightly curled, capable of being protruded
so as almost to touch the base of the peduncle or the surface of
attachment; segments short, extraordinarily numerous. In the three
posterior cirri (excepting the rudimentary rami), each segment supports
two long, slightly serrated spines, with two or three minute
intermediate ones, and with one or two very short, thick spines on the
inner and upper lateral margins: dorsal tufts with only two or three
long, fine, unequal spines. All the segments are extremely flat, broad,
short, with their anterior faces not protuberant; the greater number of
the segments, especially the lower ones, have very obscure
articulations, to be seen only with a high power, and these can be
capable of little or no movement.
_First Cirrus_ placed far from the second, with the top of its pedicel
on a level with the top of the lower segment of the pedicel of the
second cirrus; rami short, barely half the length of those of the second
cirrus; unequal, the anterior ramus being only two thirds of the length
of the posterior one; the shorter ramus contains thirteen
inverted-conical segments, with one side rather protuberant; the longer
ramus contains twenty-three thinner segments; the segments on both rami
are clothed with bristles, arranged in two or three rows, forming narrow
transverse brushes.
_Second Cirrus_, with its pedicel long, and its rami nearly equalling in
length those of the sixth pair; the two rami of nearly equal length; the
anterior one rather thicker than the posterior one; this posterior ramus
has fifty-five segments! The bristles on the second and third cirri are
arranged on the same principle as on the three posterior pair; but from
an increase in size and number of the little intermediate bristles
between the main pairs, and of those on the lateral rims, the segments,
especially the basal ones, of the anterior ramus of the second cirrus,
are clothed with thin brushes of bristles; these same bristles, on the
posterior ramus of the second, and on both rami of the third cirrus, can
hardly be said to form brushes, though longer and more numerous than
those on the three posterior pair of cirri.
_Fifth and Sixth Cirri._--These resemble each other, and have their
inner or posterior rami in an almost rudimentary condition. In the sixth
cirrus (Pl. X, fig. 28) the outer ramus (_a_) has actually sixty-three
segments, whereas the rudimentary ramus (_k_) has only eleven, nearly
cylindrical segments. These are furnished with extremely minute spines,
of which those on the dorsal face are longer than those on the anterior
face; the spines on the summit of the terminal segment are the longest;
the segments are not half as thick as the normal ones in the outer
ramus. The rudimentary ramus is only one seventh part longer than the
pedicel which supports both it and the normal ramus. In the fifth
cirrus, the rudimentary ramus is rather longer, and has thirteen
segments, resembling those in the rudimentary ramus of the sixth. In the
fourth cirrus there is no trace of this peculiar structure, the rami
being equal in length and strength. The two rudimentary rami on each
side are nearly straight, and seem incapable of movement; they project
out behind the normal rami, and closely resemble in general appearance,
the two caudal appendages; hence this cirripede, at first sight, appears
to be six-tailed.
_Pedicels of Cirri._--The pedicel of the first pair is very short; that
of the second is the longest; those of the posterior cirri decreasing in
length. Upper segments short; lower segments in the second, third and
fourth cirri, irregularly and rather thickly clothed with bristles, but
in the fifth and sixth cirri, there is a regular double row of main
spines, with some minute intermediate ones: hence there is a difference,
both in the rami and in the pedicels, between the fourth cirrus and the
fifth and sixth, and this is a unique case. On the dorsal surface of the
pedicel of the second cirrus, there is a tuft of much feathered fine
spines.
_Caudal Appendages._--Each consists of eight much tapering, very thin
segments, furnished with a few short simple spines round their upper
margins, and with a longer tuft on the terminal short segment; basal
segments twice as thick as the middle ones. In length, these caudal
appendages equal the pedicels of the sixth pair of cirri, and are a
very little shorter than the rudimentary rami of these same cirri.
_General Remarks._--Having examined this species first in the genus, I
fully anticipated that the very remarkable character of the inner rami
of the fifth and sixth cirri being rudimentary, and serving the same
function (if any) with the caudal appendages, would have been generic;
but this is not the case, for _Alepas cornuta_ cannot be separated from
_A. minuta_ without violating a clear natural affinity.
4. ALEPAS TUBULOSA.
Quoy et Gaimard. Voyage de l’Astrolabe, Pl. xciii, fig. 5, 1834.
_A. aperturâ parvâ prominente et tubulosâ: scutis et prominentiis
secundùm marginem carinalem, nullis._
Orifice small, tubular, protuberant; capitulum without horny scuta or
projections along the carinal margin.
Animal unknown.
New Zealand, Tolaga Bay. Attached to a living Palinurus.
I have given the above brief character from the plate, and imperfect
description in the voyage of the Astrolabe. The small and distinctly
tubular orifice, and the smooth carinated edge of the globose capitulum,
appear sufficiently to distinguish this species from _A. cornuta_. The
colour is stated to have been white with violet tints. Length, two
(French) lines.
ANELASMA. _Gen. Nov._ Pl. IV.
ALEPAS. _Lovén._ Ofversigt of Kongl. Vetenskaps-Akad.
Fördhandlinger: Forsta Argangen. Stockholm, 1844, p. 192,
Tab. 3.
_Capitulum sine valvis: aperturâ amplâ: pedunculus fimbriatus,
sub-globosus, infossus._
Capitulum without valves; aperture large; peduncle fimbriated,
sub-globular, imbedded.
Cirri without spines; outer maxillæ and palpi rudimentary, spineless;
mandibles minute, with several small teeth irregularly placed; maxillæ
minute, with very minute irregularly scattered spines. No caudal
appendages.
* * * * *
I owe to the great kindness of Professor Steenstrup, an examination of
this very curious cirripede, well described and figured by Lovén, who
considered it an Alepas. It lives parasitic, with its peduncle imbedded
in the skin of sharks, in the North Sea. According to the principles of
classification which I have followed, this cirripede cannot possibly
remain in Alepas, and must form a new genus; for some time, indeed, I
thought that a new family or sub-family ought to have been instituted
for its reception; but when I considered that its highly peculiar
characters are all negative, as the non-articular, non-spinose structure
of the cirri, and that no new or greatly modified functional organ is
present, I concluded that it might properly remain amongst the Lepadidæ.
We shall, moreover, hereafter see that the male of Ibla, which, of
course, must remain in the same family with the female, is, in some
analogous respects, even more abnormal than Anelasma.
1. ANELASMA SQUALICOLA. Pl. IV, figs. 1-7.
ALEPAS SQUALICOLA. _Lovén_, ut supra.
North Sea. Parasitic on Squalus.
_Capitulum_, destitute of valves; oval, much flattened; the double
membrane composing it, thin, highly flexible, coloured externally and
internally, by the underlying corium, of a blackish purple; aperture,
extremely large, extending from the upper end of the capitulum, to close
above the peduncle, gaping, and not protecting (in the dead condition)
the cirri and mouth.
The _Peduncle_ is about half as long as the capitulum, but, according to
Lovén, this part varies in length; it is a little narrower than the
capitulum; colourless, from being imbedded in the shark’s skin;
sub-globular; basal end almost hemispherical. Total length of animal
1.3; diameter of peduncle .4 of an inch.
The external membrane of the capitulum is not nearly so thick as is
usual in other Cirripedes, and is, therefore, unusually flexible. The
internal membrane, on the other hand, is very much thicker than is
usual, being only a little thinner than the outside coat; this
circumstance, as well as the similarity in colour on both sides, is
evidently due to the remarkable openness of the sack, and consequent
exposure of its inside. The inner membrane, when viewed under a high
power, is seen to be covered with the minutest spines; the external
membrane is structureless, except that there are a few rows of very
minute beads of hard chitine, like those which occur on the capitulum of
_Conchoderma aurita_. Lovén, however, states that there are imbedded in
the outer membrane, scattered, minute, dendritic, calcareous particles.
Of these, I could see no trace. There is a very thin muscular layer
between the two coats, all round the capitulum, and this layer becomes
rather thicker round the base, near the peduncle. The adductor muscle,
occupying its usual place close below the mouth, is thinner than in any
other Cirripede of the same size seen by me; nor does it end so abruptly
at each extremity, as is usual: where attached to the outer coat, no
impression is left. It is a singular fact, that in this Cirripede alone,
the fibres of the adductor, and of the muscles of the cirri, and of the
trophi of the mouth, are destitute of transverse striæ; but it is not
singular, that the muscles surrounding the capitulum should, also, be
destitute of striæ, for this is the case with the muscles which, running
up from the peduncle, surround the capitulum in Alepas, and partly
surround it in Conchoderma. It must not be inferred from the absence of
transverse striæ in the muscular fibres of the adductor and of the
cirri and trophi, that they are involuntary, but only that they are in
an embryonic condition, for I find in the natatory larva, that all the
muscles, with the exception of some connected with the eyes, are
similarly destitute, and yet perform voluntary movements.[46]
[46] Dr. C. Schmidt in his Contribution to the comparative
Anatomy of the Invertebrate animals, &c., (translated in Taylor’s
Scientific Memoirs, vol. v, p. 1,) says that in young Crustacea,
“we find plain primitive fibres, which subsequently acquire the
transversely striated aspect.”
Although in the dead state, the aperture of the capitulum seems to be
always gaping, yet I have little doubt, that the living animal can fold
the flexible membrane, like a mantle, round its thorax and cirri, and
thus protect, though feebly compared with most Cirripedes, these organs.
I suspect that the mouth is always exposed.