basal margin extremely oblique, forming an acute angle with the
occludent margin; the lateral margin is slightly hollowed out, and is
separated from the tergal margin by a large rectangular projection or
shoulder. The occludent margin is nearly straight; externally, there is
a slight ridge running down the middle of the valve, from the apex to
the baso-lateral angle; and a second ridge running from the apex to the
tergo-lateral angle. The lines of growth do not end abruptly at the
tergo-lateral angle, as is the case with _S. ornatum_ and several fossil
species, but run up a little way along the tergal margin. The umbo is
seated at the uppermost point, and, therefore, the main growth is
downwards. There is a large rounded depression for the adductor muscle
(_a_, fig. 2 _a´_), and higher up, opposite the tergo-lateral angle,
there is another hollow (_b_), for the lodgment of the males; this
latter is of nearly the same shape as the hollow for the adductor
muscle, but rather more conspicuous than it. From the appearance of the
under surface of the scuta, it might readily have been thought, that
there had been two adductor muscles.
_Terga_, of large size, longer than the scuta, flat, triangular, with
the whole inferior part much produced and spear-like. A portion of the
apex, must have projected freely above the sack.
_Carina_ (Pl. VI, fig. 2 _b´_), simply bowed (_i. e._, not rectangularly
bent), with the umbo (and primordial valve) seated at the upper point;
rather massive, narrow, only slightly increasing in width from the upper
to the lower end; the two sides are flat, and at right angles to the
roof, which is bordered on each side by a rather broad, square-topped
ridge (_see section_ fig. 2 _c´_), or the roof may be said to have a
square-edged furrow running from the apex to the basal margin, and
widening downwards; these two ridges have their lines of growth oblique,
and hence have a twisted appearance; the central depressed portion of
the basal margin, which is square or truncated, descends lower down than
the two ridges. The sides of the valve close to the apex are broad, and
consist, as I believe, of intra-parietes, as well as of parietes, but
these parts are not separated from each other by ridges, as is commonly
the case, more especially with the fossil species. I have described the
carina in some detail, on account of its resemblance to that of the
cretaceous _S. fossula_, _S. trilineatum_, and _S. quadricarinatum_.
_Rostrum_, unknown; but one probably existed.
_Upper Latera_, of large size, elongated, quadrilateral, approaching to
diamond-shaped, with the angles rounded, nearly twice as long as broad;
almost flat; upper half acuminated, lying between the scuta and terga;
the lower half broad, forming a rectangular projection lying between two
latera of the lower whorl. The umbo is near the apex, the greater part
of the growth being downwards, but the valve is added to a little, round
the two sides of the apex; these additions do not take place in the
early stages of growth, (as explained under _S. vulgare_,) and,
therefore, they form a depressed rim.
_Rostral Latera_, almost exactly triangular, curved; basal margin
furnished with a just perceptible rim.
_Infra-median Latera_, quadrilateral, sides unequal in length; the
carino-basal margin being the longest; in area not quite twice double
the rostral latera; directed obliquely upwards.
_Carinal Latera_, sub-triangular, produced upwards, with the apex
rounded, and the two lateral margins hollowed out; the basal margin
exceeds a little in length the basal margin of the rostral latera. The
umbones of these two latera are seated at their basal outer angles, so
that the growth of the valves is towards each other and upwards. The
umbo of the infra-median latus is seated at the baso-rostral angle, and
hence the growth is obliquely upwards. The umbones of the rostral latera
must have been close together, over the unknown rostrum.
_Length_ of capitulum about 4/10th of an inch.
_Peduncle_, only small fragments are preserved; the calcified scales are
small, closely imbricated, several of them together only equalling in
length the basal margin of the rostral latera. Each scale is thin,
transversely elongated; basal imbedded portion straight; upper margin
rounded.
_Mouth._--Labrum with the upper part highly bullate, forming an
overhanging projection; palpi apparently small and narrow.
_Mandibles_, narrow, produced, with three teeth; inferior angle
pectinated, as is sometimes the third tooth; the distance between the
tips of the first and second teeth equals that between the second tooth
and the inferior angle.
_Maxillæ_, extremely narrow, produced, without any notch; spinose edge
exactly one third of the length of the mandibles: beneath the two upper
great spines there are only three or four pair of spines; on the convex
upper margin there are some minute tufts of the smallest hairs.
_Outer Maxillæ_, rounded with the inner margins very sparingly but
continuously covered with bristles. I could not ascertain whether the
olfactory orifices were tubular.
_Cirri._--These consisted, in the one specimen, of merely small
fragments. The segments of the posterior cirri are elongated, not
protuberant, and support, I believe, five pair of non-serrated spines,
and an exterior row of very minute spines: dorsal spines fine and long.
Either the second or third cirri, or probably both, are remarkable for
having the whole of one side of each segment covered with irregular rows
of long spines. Moreover, in the upper segments of these same cirri,
between each separate dorsal tuft, there is placed one or two long
bristles. The first cirrus appears to have had very broad segments, and
these are singular from the spines in the dorsal rows, being extremely
long. In some of the cirri, several of the basal segments are soldered
together.
_Caudal Appendages_, lost.
From the state of the specimen, it was quite impossible to ascertain
whether the individual here described was an hermaphrodite or female;
from the analogy of its nearest congener, _S. ornatum_, the latter is
the most probable; but the genus Ibla shows how the sexes may differ in
the most closely-allied forms.
_Affinities._--From the hollows on the under sides of the scuta, for the
lodgment of the males; from the umbones of the scuta and of the carina
being situated on the apices of these valves; and from all the
characters of the mouth, _S. rutilum_ is much more closely allied to _S.
ornatum_ than to any other species.
MALE, OR COMPLEMENTAL MALE.
In the concavity or hollow above the depression for the adductor muscle
(Pl. VI, fig. 2 _a´_), I found males, but in so extremely decayed a
condition, that they could hardly be examined. On one side, however, I
distinctly saw the larval prehensile antennæ, with pointed, hoof-like
discs; and part of the thorax, with its small limbs and long spines, as
in _S. vulgare_ or _S. ornatum_. I also saw clearly the eye. The four
calcified beads or rudimentary valves, I believe, were present; but in
removing the specimen, the whole fell to pieces and was lost. The outer
integument was covered with rather thick, very minute bristles, each
about, 2/10,000th of an inch in length, and therefore only half the
length of those on the complemental males of _S. vulgare_. The cavities
for the males are not formed, as in _S. ornatum_, by the thickening of
the internal surface of the valve round a defined space, but by the
scutum being externally convex and internally concave down the middle,
hollows being thus produced both for the lodgment of the males and for
the attachment of the adductor muscle. These hollows are separated from
each other by a slight transverse ridge. I do not know at which point of
the margin of the valve, the orifice of the male is situated, but I
presume close under the apex. In this species, as in _S. ornatum_, there
can be no question that the scuta of the female are specially modified
by their own growth for the reception of the males. It must be added
that, as it was not possible to ascertain whether the ordinary form of
_S. rutilum_ was hermaphrodite or female, so it must remain doubtful
whether the parasites are males or complemental males; but the former, I
think, is most probable.
[=TT= SUB-CARINÂ PRESENTE.]
4. SCALPELLUM ROSTRATUM. Pl. VI, fig. 7.
_S. (Herm.) valvis 15: rostro permagno: laterum paribus quatuor: pari
superiore pentagono._
(Herm.) Capitulum with 15 valves: rostrum very large: four pair of
latera; upper latera pentagonal.
Mandibles with four teeth; maxillæ with the inferior angle prominent.
_Complemental Male_, attached between the mouth and adductor scutorum
muscle; pedunculated; capitulum bearing a pair of elongated scuta and a
rudimentary carina; mouth and cirri prehensile.
Philippine Archipelago; Island of Bantayan. Attached to a horny
coralline: 20 fathoms. Mus. Cuming.
HERMAPHRODITE.
_Capitulum_, with the upper part narrow and produced.
_Valves_, 15 in number, placed close together, clouded pale red, covered
with membrane, which is thickly clothed with minute points.
_Scuta_ rather small, oval, with the upper end pointed; rather convex;
basal and lateral margins blending into each other; the upper produced
portion above the umbo is small; there is a deep pit for the adductor
muscle, and there is a fold on the occludent margin in the usual
position; occludent margin not straight.
_Terga_ large, one third of their own length longer than the scuta; fat,
sub-triangular; the three margins are not quite straight; the carinal
margin projects a little above the apex of the carina, and the scutal
margin is excised to fit the upper part of the scuta.
_Carina_ bowed, internally deeply concave; upper portion above the umbo,
about one fourth of the total length, extending between the terga for
two thirds of their length, up to the slight prominences on their
carinal margins: a ridge separates, on each side, the parietes from the
tectum.
_Rostrum_ (fig. 7 _a_) unusually large, about two thirds of the length
of the scuta, and twice as long as the rostral pair of latera;
internally concave, externally carinated; outline of the upper portion
acutely triangular, of the lower portion rounded; umbo seated at the
upper end.
_Upper Latera_ pentagonal, with the apex rounded.
_Rostral Latera_ flat, four-sided, with the basal margin the longest,
and the baso-carinal angle produced.
_Infra-median Latera_ nearly equalling in area the upper latera; not
descending so low down as the rostral and carinal latera; outline of
lower half semi-oval, of upper half rectangular.
_Carinal Latera_ flat, four-sided, with the basal margin the longest,
and slightly protuberant; baso-rostral angle produced; whole valve
larger than the rostral latus, but closely resembling it in form.
_Sub-carina_ minute, not above one third of the size of the rostral
latera, which are the smallest of the other valves; internally deeply
concave; externally solid, pyramidal, standing out beyond the surface of
the carina, with the umbo at the apex.
The umbones of the four pair of latera are seated a little above the
centre in each valve, on the summit of a raised triangular portion; this
arises from the valve at first growing only downwards, and when added to
at the upper end, the new part forms a ledge at a lower level round the
old part, which had already acquired some thickness.
_Peduncle_, short, about half the length of the capitulum; narrow;
thickly clothed with minute, longitudinally elongated, spindle-shaped,
calcareous scales or beads, which project but little.
_Length_ of the capitulum, rather under 3/10ths of an inch.
In a _Young Specimen_, with its capitulum, together with the peduncle,
only 1/10th of an inch long, the scuta, terga, and carina are very large
in proportion to the valves of the lower whorl. The latter project
more, and are externally more pointed, as in the genus Pollicipes. The
rostrum is well developed; the infra-median latera, in proportion, are
the least of all the valves. The carina is straight and pointed, and
not, relatively to the scuta, quite so long. The scuta are rather
broader in proportion to their length, which would naturally follow from
less having been added to their apices,--these valves at first growing
only downwards. The membrane covering and connecting the valves is
furnished with long thin spines.
_Mouth._--Labrum placed far from the adductor scutorum muscle, with the
upper part exceedingly prominent; apparently there are no teeth on the
crest. Palpi blunt.
_Mandibles_, narrow, with four teeth, of which the second is not smaller
than the others; inferior angle sharp and produced, barely pectinated.
_Maxillæ._--Under the two or three great upper spines, there is a tuft
of fine bristles; the inferior part of the edge is step-like, and much
upraised.
_Outer Maxillæ_, with the inner edge deeply notched, and the bristles
arranged in two quite distinct tufts; the bristles on the outer surface
are long. Olfactory orifices, thin, tubular, and projecting.
_Cirri._--The first pair is placed far from the second; the three
posterior pair are long and straight, with their segments much
elongated, not protuberant, bearing four or five pair of long spines,
with little intermediate tufts of minute spines, and with the minutest
spines on the lateral upper edges. Dorsal tufts with one spine extremely
long, equalling a segment and a half in length; the others very short.
Spines all serrated. First cirrus not very short; rami nearly equal,
with the four terminal segments of both tapering; all the basal segments
much thicker, and thickly covered with bristles. Second cirrus (as well
as the third in a less degree), with the anterior ramus thicker than the
posterior ramus, and with all the lower segments in both rami thickly
clothed with three or four longitudinal rows of spines.
_Caudal Appendages_, spinose, uni-articulate; but the specimen was
injured, and I could not exactly make out their shape: I believe it was
oval, and thickly fringed with fine spines.
_Penis_, very small, almost rudimentary, narrow, and hairy, scarcely
exceeding in length the pedicel of the sixth cirrus.
COMPLEMENTAL MALE. Pl. VI, fig. 5.
Before describing the parasite of the present species, which departs
entirely from the character of the males of the three preceding species,
it is proper to state that I consider it to be a Complemental Male
simply from analogy, as will hereafter be more fully shown at the end of
the genus. Had a specimen of the parasite been brought to me without any
information, I should have concluded that it was an immature individual
of a new genus of pedunculated Cirripedes, remarkable from the
rudimentary condition of the valves, and exhibiting, in one important
character, namely, in the form of the larval prehensile antennæ, an
alliance to Scalpellum. Had I been then told that three individuals in a
group, had been found attached to _S. rostratum_, not outside the
valves, but to the integument, in a central line, between the labrum and
the adductor scutorum muscle, in such a position that when the
Scalpellum closed its valves, these parasites were enclosed within the
capitulum, my surprise would have been great; for it is very improbable
that this singular and unparalleled position was accidental in this one
group of specimens, inasmuch as there seems to be a relation between the
naked condition of the capitulum of the parasite, and the protection
afforded to it by the capitulum of the Scalpellum. It further becomes
apparent on reflection, that these minute parasites, though having the
appearance of immaturity, can not increase in size, or but little, for
if they did grow, and acquired an ordinary size, they would either be
killed by the pressure of the scuta of the Scalpellum, or they would
destroy the latter, and in doing so soon lose their own support, and
thus necessarily perish!
The one full-grown specimen of _S. rostratum_, in Mr. Cuming’s
collection, was in a good state of preservation, but dry. The three
parasites were attached, as stated, close under the labrum, between it
and the adductor muscle. They are constructed like ordinary Cirripedia,
and have a mouth, thorax and cirri, enclosed in a capitulum, supported
on a peduncle of moderate length and narrow. The entire length of the
capitulum and peduncle, as far as could be ascertained in the shrivelled
condition of the specimens, was 35/1000ths, and the greatest width of
the capitulum 11/1000ths of an inch. Both capitulum and peduncle are
hirsute with spines, nearly 1/1000th of an inch in length, mingled with
shorter hairs in little rows of three and four together. The figure (5)
in Pl. VI is merely a restoration, as accurate as could be made from the
much shrivelled specimens. There are only three valves,--namely, an oval
carina (_a_), seated rather high up on the capitulum, in a rudimentary
condition and only 1/1000th of an inch in length, and a pair of scuta;
these latter consist of a narrow, slightly curved plate, 8/1000ths in
length, broadest at the lower end, where the breadth is 2/1000ths of an
inch. The prehensile antennæ, at the end of the peduncle, have pointed
hoof-like discs: I was not able to make out the other parts. It deserves
notice, that in the young specimen of the ordinary form of _S.
rostratum_, 1/10th of an inch in length, and therefore only thrice as
long as the parasites, all the valves were perfect, and seemed to have
followed the ordinary law of development.
_Mouth._--The largely bullate labrum is placed far from the adductor, in
the same manner as in the hermaphrodite. The mandibles have three large
sharp teeth, with the inferior point very sharp and small, so that there
is one less tooth than in the hermaphrodite. The maxillæ have two or
three large upper spines, the others being very thin; I believe the
lower part is upraised and step-like, as in the hermaphrodite. The
outer maxillæ are bilobed in front, with a few short bristles on the
outer side near the bottom. I was not able, from the dried state of the
specimens, to discover whether the olfactory orifices were tubular.
Altogether it was apparent, from this imperfect examination, that there
was a close similarity between the mouth of the parasite and of the
hermaphrodite.
The _Thorax_ is unusually elongated.
_Cirri._--The first pair is very short, and is distant from the second.
All have the appearance of immaturity, with their pedicels very long in
proportion to their rami; the latter are slightly unequal in length,
even in the sixth pair. There appeared to be six segments in the rami of
the sixth pair, each segment bearing two or three pair of long spines.
_Caudal Appendages_, with two or three little spines on their summits.
_Penis_, short, blunt, thick at the apex, with one or two spines on it.
I did not see any ovaria, but this could hardly have been expected in
specimens in a dried condition, without they had happened to have been
in a gorged condition. Certainly there were no ova.
In the general summary at the end of the genus, I shall give my reasons
for believing this parasite to be the Complemental Male of the
_Scalpellum rostratum_.
5. SCALPELLUM PERONII. Pl. VI, fig. 6.
SMILIUM PERONII. _J. E. Gray._ Annals of Philosoph., new series,
tom. x, 1825.
---- ---- . . . . . Spicilegia Zoologica, tab. iii, fig. 10, 1830.
ANATIFA OBLIQUA. _Quoy_ et _Gaimard_. Voyage de l’Astrolabe, Pl.
xciii, fig. 16, 1823-1834.
POLLICIPES OBLIQUA. _Lamarck._ An. sans Vertebres (2d edition).
_S. (Herm.) valvis 13: laterum paribus tribus; pari superiore multùm
elongato: pedunculi squamis calcareis nullis._
(Herm.) Capitulum with 13 valves: three pair of latera; upper latera
much elongated: peduncle without calcareous scales.
Mandibles with 10 or 11 unequal teeth: maxillæ with the edge nearly
straight, bearing numerous spines.
COMPLEMENTAL MALE, attached externally, between the scuta and below the
adductor muscle; pedunculated; capitulum formed of six valves, with the
carina descending far beneath the basal angle of the terga; mouth and
cirri prehensile.
Swan River, Australia, attached to a coralline; Mus. Cuming.
Port Western, Bass’s Straits, as stated in the Voyage of the
Astrolabe. Mus. Brit.
HERMAPHRODITE.
_Capitulum_ formed of 13 valves; namely, two scuta, two terga, a carina
and sub-carina, a rostrum, a pair of upper latera, and two pair of lower
latera; these latter valves, with the sub-carina and the rostrum, make a
whorl of six pieces. The upper part of the capitulum is, as usual,
produced. The upper valves are separated (in specimens which have not
been dried) by rather wide interspaces of membrane; they are covered
(excepting, generally, their umbones,) by membrane, which in the
interspaces is clothed with fine spines. The spines, or the marks where
they were once articulated, are visible over nearly the entire surface
of the membrane covering the valves. The spines are particularly
numerous round the orifice of the sack. The whole capitulum, (in a dried
condition), is coloured dull purplish-red, which is only in part due to
the underlying corium, for the valves themselves are pale red. After
having been long kept in spirits, the whole capitulum becomes
colourless. The valves are smooth, faintly marked by lines of growth.
The umbones of the lower valves project outwards, giving a denticulated
appearance to the base of the capitulum.
_Scuta_, slightly convex, oblong, breadth about two thirds of the
length, almost quadrilateral, with the upper portion produced into a
flat projection; this projection is almost spear-shaped, being
constricted a little on each side below the apex. There is a deep pit
for the adductor muscle. The umbo is near the apex, the part above not
being above one fifth of the whole length of the valve. As in _S.
vulgare_, the growth is at first downwards, and subsequently a little
upwards and downwards, thus producing the upper, small, spear-like
projection, which lies at a lower level than the umbo. There is a fold
on the occludent margin.
_Terga_, large, flat, triangular; carinal margin slightly hollowed out;
occludent margin slightly arched, with a small portion protuberant to a
variable amount. The apex is slightly curved towards the carina.
_Carina_, long, internally deeply concave, angularly bent, the lower
portion slightly longer and wider than the upper part; the two halves
meet each other at about an angle of 135°; the upper half is parallel to
the longer axis of the terga, between which it extends for three fourths
of their length. The external surface is rounded, except near the umbo,
where the edge is carinated; growth almost equally upwards and
downwards; the parietes and tectum are not separated by ridges.
The _Sub-carina_ lies close under the carina, and is placed almost
transversely to the longer axis of the capitulum; external surface
arched and smooth, the whole having the shape of half of a cone, with
the apex a little curved outwards; seen internally, it may be said to be
formed of two triangular wings placed at right angles to each other;
basal margin straight; in size equalling the carinal latera.
_Rostrum_, lying almost transversely to the longer axis of the
capitulum, under the basal margins of the scuta; in shape (fig. 6 _a_)
closely resembling the sub-carina, but about one third larger than it;
larger also than either the rostral or carinal latera; seen externally,
appears like a half cone; seen internally, is formed of two triangular
wings (with curved edges), placed at right-angles to each other.
_Upper Latera_, internally flat, oblong, twice as long as broad; upper
end square, truncated; upper half rather wider than the lower half;
fully twice as large as either of the lower latera. The basal points
extend below the basal margins of the scuta. The umbo is placed a little
above the centre.
_Rostral Latera_, minute, scarcely exceeding one third of the size of
the carinal latera, and very much less than the rostrum; they are placed
transversely under the basal point of the upper latus, or rather between
it and the baso-lateral angle of the scutum; basal margin, as seen
internally, straight; upper margin arched; rostral angle produced;
internally flat; the whole valve is very thick and solid, so that the
umbo which lies at the rostral end, projects rectangularly outwards.
_Carinal Latera_, oblong, nearly quadrilateral, with the upper angle
produced; placed obliquely, parallel to the lower half of the upper
latera; umbo slightly prominent, seated near the apex, with three
rounded ridges proceeding from it; internal surface very slightly
concave.