one (_h_) is seated on the posterior margin of a swelling, beneath the
basal articulation of the first cirrus, and this is the longest; the
second (_g_) is short and thick, and is seated a little lower on the
side of the prosoma, (near to this, there are also two little pap-like
eminences;) the third (_i_) is seated on the posterior margin of the
pedicel of the first cirrus, above the basal articulation; the fourth,
fifth, and sixth (_j_, _k_, _l_) in similar positions on the pedicels of
the third, fourth, and fifth cirri. These three latter filaments are
shorter and smaller than the first three. At the base of the second
cirrus, which has no proper filament, there is a swelling as if one had
been united to it.
_Mouth._--_Mandibles_, with the basal edges of the five teeth pectinated
by minute, short, strong spines on one side; inferior angle extremely
short. In one specimen, there was a minute pectinated tooth between the
first and second; in another, the second tooth was bifid on its summit;
in another, the fourth was rudimentary.
_Maxillæ_, with five steps: sometimes each step commences with a spine
rather larger than the others; at the upper angle, there are two large
unequal spines (neither pectinated,) with a third longer and thinner,
seated a little below. _Outer maxillæ_ (Pl. X, fig. 16), simple.
_Cirri_, with twice as many segments in the sixth cirrus as in first;
spines on the first and second cirri doubly serrated.
_Colours_ (when alive).--Capitulum and peduncle grey, with a tinge of
blue, with six black bands, tinged with purplish brown. The two bands
near the carina become confluent on the peduncle, and sometimes
disappear; the carina is edged, and the interspace between the two
scuta, coloured with the same dark tint. The whole body and the pedicels
of the cirri are dark lead-colour, with the segments of the cirri almost
black: in some specimens, the colour seems laterally abraded from the
cirri. Ova white, becoming in spirits pinkish, and then yellow. The dark
bands on the capitulum and peduncle become in spirits purple; but are
sometimes discharged; the general grey tint disappears. Professor
Macgillivray states that many individuals are light-brown or
yellowish-grey, with irregular brown streaks, or crowded dots: he states
that in very young specimens the colours are paler, and the valves
spicular.
_Size._--The largest specimen which I have seen, had a capitulum rather
above one inch long and three fourths of an inch wide: growth very
rapid.
_Monstrous Variety._--In the British Museum, there is a dried and
somewhat injured specimen of a monstrous variety, the _Pamina
trilineata_ of J. E. Gray: it differs from the common form only in
having a tubular projection, just behind the notch separating the upper
points of the terga; this tube springs from over the terga, and is,
therefore, in a different position from the ear-like appendages in
_Conchoderma aurita_. It does not open into the sack: the membrane
composing it appears to have been double in the upper part, and to have
been lined with corium: in short, this tube seems to have been an
excrescence or tumour, of a cup or tubular form.
_General Remarks._--It will have been seen how much subject to variation
the valves of this species are. When I first examined the _Cineras
chelonophilus_ of Leach, from 36° N. lat., Atlantic Ocean, and found in
many specimens, both old and young, that the terga were very small,
flat, acuminated at both ends, with a projecting shoulder on the carinal
margin, and situated at about their own length from the apex of the
carina, and at twice their own length from the scuta; and when I found
the carina acuminated at both ends, and the scuta very imperfectly
calcified, with the lateral lobe broad, flat, and standing out at right
angles; and lastly, when I found the whole capitulum bluntly pointed,
instead of being square on the summit, I had not the least doubt, that
it was a quite distinct species. Afterwards, I found in the _Cineras
Olfersii_ of Leach, from the South Atlantic, the same form of terga; but
within slightly more concave or furrowed, and not nearly so small, and
therefore not placed at above half so great a distance from the other
valves; and here, the carina had its usual outline, as had nearly the
scutum on one side, whereas, on the other side, it presented a new and
peculiar form, having five ridges or points, and was imperfectly
calcified; seeing this, it was impossible to place much weight in the
precise form or size (and therefore, relative separation,) of the
calcified valves; and on close examination, I found every part of the
mouth and cirri identical in Leach’s _Cineras chelonophilus_ and _C.
Olfersii_, and in the common form. Therefore, I conclude, that _C.
chelonophilus_, and still more _C. Olfersii_, are only varieties; the
terga presenting the greatest, yet variable, amount of difference,
namely, in their acumination and flatness. We know, also, that in the
species of the closely allied genus of Lepas, the terga are very
variable in shape, and this is the case, even in a still more marked
degree, in _Conchoderma aurita_. Professor Macgillivray, I may add, has
come to a similar conclusion regarding the extreme variability of the
valves of this species.
As the varieties here mentioned are very remarkable, and may perhaps
turn out to be true species, I think they are worth describing in some
detail: I will only further add, that we must either make several new
species, or consider, as I have done, several forms as mere varieties.
C. VIRGATA, var. CHELONOPHILUS of _Leach_. Pl. III, fig. 2 _c_.
Atlantic Ocean, 35° 15´ N., 16° 32´ W. On the Testudo caretta.
Capitulum not above half an inch long, composed of very thin membrane,
with six bands (as stated by Leach) of faint colour; summit bluntly
pointed; valves very small, far distant from each other; the scuta are
imperfectly calcified, the central part of the umbo consisting of thick,
brown chitine, with imbedded shelly beads; terga and carina perfectly
calcified.
_Scuta_ trilobed, flat, within slightly concave, upper lobe rather more
acuminated than the lower; lateral lobe triangular in outline, twice as
wide as either the upper or lower lobes; lying in the same plane with
them and standing out at almost exactly right angle.
_Terga_, flat; placed obliquely to the scuta, and barely half as long;
separated from them by nearly twice their own length; upper and lower
points acuminated; the umbo on the carinal margin forms a projecting
shoulder; the scutal margin is straight, they are separated by nearly
their own length from the apex of the carina.
_Carina_ narrow, very slightly arched, within slightly concave, both
points acuminated; lower third rather wider than the upper part; in
length equalling three fourths of the scuta, and longer by one third
than the terga; about as wide as the latter.
_Filaments, Cirri, and Mouth_ exactly as before.
In some specimens sent to me by the Rev. R. T. Lowe from off the
_Testudo caretta_, taken near Madeira, the scuta have their lateral
lobes broad and nearly rectangular: the carina extends nearly to between
the terga: the terga are nearly straight, somewhat pointed at both ends,
distant from the scuta, almost solid within, with their upper points
bowed outwards: the whole capitulum is bluntly pointed, as in the _var.
chenophilus_, to which form this makes a rather near approach.
C. VIRGATA, var. OLFERSII.
CINERAS OLFERSII. _Leach._ Tuckey’s Congo Expedition.
_Hab._ South Atlantic Ocean.
_Scuta_, unlike on the opposite sides of the same individual, on one
side with a single lateral lobe as usual, but this very narrow, on the
other (fig. 2 _d_), with five lobes or projections.
_Terga_ slightly concave within, separated by a little more than their
own length from the tips of the scuta, and by one third of their own
length from the tip of the carina.
_Carina_ longer than the scuta by about one fifth or one sixth of its
own length, blunt at both ends, considerably bowed.
Again, I possess a group of remarkably fine specimens given me by Mr. L.
Reeve, from the southern ocean, (as I infer from a young _Lepas
australis_ adhering to them,) in which all the individuals, young and
old, are characterised as follows:--Scuta, with the lateral lobe
generally broad, but to a very varying extent, with the upper and lower
lobes extremely sharp. Terga separated from the scuta, by one and a
fourth of their own length, and by their own length from the carina;
somewhat acuminated at both ends, nearly straight, with a very slight
shoulder near the umbo. Carina equalling the terga in length, and about
three fourths of the length of the scuta; neither the upper nor lower
point much acuminated. All the valves most imperfectly calcified: in one
specimen, the scutum on one side was simply horny, without a particle of
calcareous matter. The summit of the capitulum nearly intermediate in
outline between the common square, and bluntly-pointed form of _var.
chelonophilus_. I compared the cirri and trophi with those of a common
variety, and could detect not the smallest difference. This variety
differs from _var. Olfersii_, in the less development of its carina, and
from _chelonophilus_, in the greater development of its carina, and
especially of its terga. It would appear as if the great variability of
the valves was connected with the absence of calcareous matter.
3. CONCHODERMA HUNTERI. Pl. III, fig. 3.
CINERAS HUNTERI. _R. Owen._ Cat. Mus. Coll. of Surgeons, (1830),
Invert. Part I., p. 71.
_C. valvis angustis: scutis trilobatis, prominentiâ laterali non latiore
quam inferior: tergorum parte superiore pæne rectangulè secundùm
aperturæ marginem flexâ: carinâ valde arcuatâ: pedunculo brevi, in
capitulum coalescente._
Valves, narrow: scuta, trilobed, with the lateral lobe not wider than
the lower one: terga, with the upper part bent almost rectangularly
along the margin of the orifice: carina considerably arched: peduncle
short, blending into the capitulum.
No filament attached to the pedicel of the second cirrus.
_Var._--Carina absent; scuta, with the upper lobe absent; terga, with
the rectangular projection little developed.
Attached to the skin of a snake, probably the Hydeus or Pelamis
bicolor, and therefore from the tropical Indian or Pacific
Oceans. Mus. Coll. of Surgeons.[40]
[40] I owe to the kindness of Professor Owen, an examination of
these specimens, and information regarding them.
_Capitulum_, with the membrane very thin; summit obtusely pointed.
Valves linear and thin.
_Scuta_, elongated, flat, with the upper projecting lobe rather more
acuminated than the lower, and equalling it in length; lateral lobe not
wider than the lower, and about as long as it, forming an angle of about
55° with the upper one.
_Terga_, of somewhat variable length, generally about half as long as
the carina, narrow, and of nearly equal width throughout; lower point
sharp; externally convex; internally solid, with a trace of a central
depressed line; the upper fourth part generally a little bowed out of
the plane of the lower part, and abruptly bent at rather above a right
angle along the occludent margin of the orifice. These valves are
situated at about half their own length from the upper points of the
scuta.
_Carina_ considerably arched, extending to the lower points of the
terga, or running up between them for even half their length; equally
narrow throughout; scarcely broader than the terga; both points rounded;
internally concave; the lower point does not extend as far down as that
of the lower lobe of the scuta.
_Peduncle_, narrow, shorter than the capitulum, which, in the largest
specimen was 4/10ths of an inch long. Longitudinal purple bands appear
to have originally existed on the peduncle.
_Filamentary Appendages, trophi and cirri_ all similar to the same parts
in _C. virgata_; but perhaps the anterior faces of the segments in the
posterior cirri are rather less protuberant; perhaps also the first
cirrus is rather shorter in proportion to the sixth cirrus.
_Variety_ (_monstrous_).--Amongst the specimens, I found one very young
one, in which the scuta had not upper lobes, so that in outline they
exactly resembled the scuta in the quite distinct _C. aurita_: there was
not even a rudiment of a carina: the tergum, _on one side_, was
externally bordered by a projecting, semicircular, calcified disc; and
the upper points of both terga showed only traces of the rectangular
projection, which is the chief characteristic of _C. Hunteri_. From
these traces alone, and from the specimen being mingled with the others,
do I here include this variety.
_General Remarks._--I have very great doubts whether I have acted
rightly in considering this as a species; but as there were many
specimens, old and young, all differing remarkably from the common
species, this form anyhow deserves description. The points by which it
can be distinguished from _C. virgata_, are--the almost rectangular
manner in which the upper portion of the tergum is bent outwards and
along the orifice of the sack--the narrowness of all the valves, and
especially of the lateral lobes of the scuta,--and lastly, the greater
curvature of the carina, which in some specimens runs up far between the
terga; had this last character been constant, it would have been an
important one, but such is far from being the case. Great as are these
differences in the valves, and though common to many specimens, they are
not sufficient to convince me that it is a true species, and I should
not be at all surprised at varieties, intermediate between it and the
common form, being hereafter found;--had a name not been already
attached to it, I should not have given one. In the monstrous variety
described, we see to what an extent the valves may vary. The _C.
Hunteri_ approaches nearest to the var. of _C. virgata_, called by Leach
_Cineras chelonophilus_, for in both, the top of the capitulum is
bluntly pointed and the terga are solid within; in the _Var.
chelonophilus_, the terga and carina are minute, whereas here, though
very narrow, they are much elongated. Certainly _C. chelonophilus_ has
almost as strong a claim to rank as a species as _C. Hunteri_; but, in
the former, by the aid of other varieties, the differences were almost
reduced to the peculiarities in the terga--the valves, the most subject
to variation. In _C. Hunteri_ we have other differences, and the form of
the terga is even still more peculiar. I have, therefore, provisionally
attached to it the specific name by which it is designated in the Museum
of the College of Surgeons. From having been long kept in spirits, all
aid from colour is lost.
_Genus_--ALEPAS. Pl. III.
ALEPAS. _Sander Rang._ Manuel des Mollusques, 1829.
ANATIFA. _Quoy_ et _Gaimard_. Voyage de l’Astrolabe, 1834.
TRITON. _Lesson._ Voyage de la Coquille, 1830.
CINERAS. _Lesson._ Secundum Sander Rang.
_Capitulum aut sine valvis, aut scutis corneis, pæne abditis._
Capitulum without valves,[41] or with horny, almost hidden, scuta.
[41] Any one not attending to the characters derived from the
softer parts of the Balanidæ and Lepadidæ, might easily confound
with Alepas the genus Siphonicella (genus nov.), which,
undoubtedly, though having the external appearance of a
pedunculated cirripede, belongs to the Balaninæ, and is closely
related to Coronula.
Filaments seated beneath the basal articulations of the first pair of
cirri; mandibles, with two or three teeth; maxillæ notched, with the
lower part irregular, projecting; caudal appendages multi-articulate.
Attached to various living objects, fixed or floating.
_Capitulum_ either entirely destitute of valves, or with transparent
horny scuta, not containing any calcareous matter, and almost hidden in
membrane. These scuta are formed of a lower and a lateral lobe, placed
at above right angles to each other; they are added to by successive
layers, and closely resemble in shape the scuta of the _Conchoderma
aurita_. The orifice in _A. tubulosa_ projects so much as to be almost
tubular. In _A. parasita_ and _A. minuta_ it does not project, and is
either moderately large, or very small in proportion to the length of
the capitulum; from contraction it is much wrinkled. The membrane
forming the capitulum is smooth and very transparent; it contains very
few tubuli, except under certain irregular projections in _A. cornuta_.
The _Peduncle_ is rather short and narrow; it blends into the capitulum,
and is not, in some of the species, separated from it by any distinct
line; the surface of attachment is rather wide. Within the peduncle we
have the three usual layers of striæ-less muscles; namely, the innermost
and longitudinal, which run lower down than the others; the middle and
transverse; and, lastly, the exterior, oblique muscles, which cross each
other (becoming transparent) on the rostral central line. These several
muscles run up from the peduncle and surround the capitulum; from the
transparency of the membranes they can be seen from the outside: they
are particularly conspicuous round the orifice, which they probably
serve to close. There is, in all cases, the usual adductor scutorum
muscle (with transverse striæ), which is attached under the horny scuta,
where such exist. The fact of the striæ-less muscles of the peduncle
surrounding the whole capitulum, has been observed only in one other
genus, namely Anelasma. In consequence of this structure, the capitulum
must possess considerable powers of contraction.
The antennæ of the larva in the _Alepas cornuta_ and _A. minuta_ have
the sucking disc nearly circular, with the spines unusually plain on the
distal as well as proximal margin. Basal segment broad, much constricted
where united to the disc. The ultimate segment has on the middle of the
outer margin, in _A. cornuta_, two minute spines, which I have not
observed in any other cirripede: on the summit there are the usual
spines.
_Size._--Three of the species are small.
_Filamentary Appendages._--These are rather small; there is only one on
each side, situated on the posterior margin of a slight swelling,
beneath the basal articulation of the first cirrus; and therefore in the
position in which the filaments are most constant in Lepas, and where
they likewise occur in Conchoderma.
_Body._--The prosoma is either pretty well developed or is small,
according as the first cirrus is placed near to, or far from the second
cirrus.
_Mouth._--Labrum moderately bullate, with the lower part more or less
produced; crest with blunt, bead-like teeth, and short hairs.
_Palpi_ (Pl. X, fig. 8), acuminated and narrow to an unusual degree.
_Mandibles_, with two or three teeth, and the inferior angle acuminated;
the lateral bristles unusually strong, so as to give the main teeth the
_appearance_ of being pectinated.
_Maxillæ_, widely notched, with three great upper spines; the part
beneath the notch projecting, and either straight or irregular.
_Outer Maxillæ_, with the inner bristles either continuous or divided
into two groups: exteriorly there is a smaller or larger prominence,
with long bristles. The olfactory orifices are either slightly, or not
at all protuberant.
_Cirri._--In the three posterior pair, the segments have their bristles
arranged in a transverse row, either in the form of a narrow brush, or
consisting only of a single pair with two or three minute, intermediate,
and lateral marginal spines. The anterior ramus of the second cirrus is
thicker, and more thickly clothed with spines than is the posterior
ramus: this latter ramus, however, and both rami of the third cirrus,
are rather more thickly clothed with spines than are the three posterior
pair. The unique case in _A. cornuta_ of the inner rami of the fifth and
sixth cirri being rudimentary (Pl. X, fig. 28) will be minutely
described under that species.
_Caudal Appendages_, thin, tapering, multi-articulate, about as long as
the pedicels of the sixth cirrus.
_Stomach._--The oesophagus runs in a somewhat sinuous course, and enters
the top of the stomach obliquely. There are no cæca. The biliary
envelope presents a reticulated structure, instead of the usual
longitudinal folds.
_Generative System._--The penis is hairy, not very long, and ringed or
articulated in an unusually plain manner; the space between each ring
being about one fourth of the diameter of the penis: the unarticulated
basal portion or support is here remarkably long. The vesiculæ seminales
are long, tortuous, and enter the prosoma. The ovarian tubes are of wide
diameter: in _A. cornuta_ they surround the whole capitulum. The
ovigerous fræna are small, constricted at the base, and square on the
free margin, which is studded with minute glandular beads, borne on the
finest footstalks.
_Range._--Southern shores of England, Mediterranean, Atlantic,
West Indies, New Zealand, attached to various objects. _A.
parasita_ has been always taken on Medusæ.[42]
[42] It appears that Solander (Dillwyn Des. Cat., vol. i, p. 34)
observed a species of this genus adhering to a Medusa on the
coast of Brazil. Mr. Cocks informs me that an Alepas, apparently
_A. parasita_, has been cast on shore near Falmouth, attached to
a Cyanæa; and that two other specimens adhered to the bottom of a
vessel arriving at that port from Odessa.
_Affinities._--This genus differs from all, except Anelasma, in the
manner in which the striæ-less muscles of the peduncle run up and
surround the capitulum, and likewise in the reticulated character of
the biliary envelope of the stomach. To Conchoderma, especially to _C.
aurita_, there is manifest affinity in the form of the horny scuta:
there is also some affinity to this same genus in the presence of
filamentary appendages though here little developed, and in the circular
form of the disc of the larval antennæ, and, lastly, in the ovarian
tubes in _A. cornuta_ surrounding the capitulum. There is quite as
close, if not closer affinity to Ibla, in the following
peculiarities,--in the curved oesophagus,--in the general character of
the cirri and trophi, with the olfactory orifices in one species in some
degree prominent,--in the multi-articulated caudal appendages,--and in
the plainly-articulated penis, with its elongated unarticulated support,
though both these characters are exaggerated in Ibla. Lastly, the scuta
in Ibla, though not at all resembling in shape those of _A. cornuta_,
are formed without calcareous matter; and again, in Ibla, the muscles of
the peduncle run up to the bases of the valves, and so almost surround
the space in which the animal’s body is lodged.
The four species of Alepas appear to form two little groups; viz. _A.
parasita_ and _A. minuta_ on the one hand, and _A. cornuta_ and _A.
tubulosa_ on the other.
1. ALEPAS MINUTA. Tab. III, fig. 5.
ALEPAS MINUTA. _Philippi._ Enumeratio Mollusc. Siciliæ, 1836,
Tab. xii, fig. 23.
---- ---- _A. Costa._ Esercitazione Accadem., vol. ii, part I, Naples,
1840, Pl. iii, fig. 5 (secundum Guerin in Revue Zoolog.,
1841, p. 250.)
---- ---- _Chenu._ Illust. Conch., Pl. iii, figs. 8-10.
_A. aperturâ non prominente, capituli longitudinis vix tertiam partem
æquante: scutis corneis, pæne absconditis: longitudine totâ ad quartam
unciæ partem._
Orifice not protuberant, one third of the length of the capitulum:
scuta horny, almost hidden. Total length quarter of an inch.
Outer maxillæ, with the spines in front continuous; posterior cirri,
with several long spines arranged in a transverse row on each segment;
caudal appendages longer than the pedicels of the sixth cirrus.
Sicily; attached to a Cidaris:[43] island of Capri (_A. Costa_).
[43] I am greatly indebted to Professor J. Müller, of Berlin, for
kindly lending me specimens.
Capitulum oval, blending insensibly into the peduncle; moderately
flattened; composed of thin structureless membrane, with the exception
of two horny, almost quite hidden scuta. Orifice situated near the
summit, and in a line, which is oblique to the longitudinal axis of the
peduncle; much wrinkled; barely one third of the length of the whole
capitulum.