capitulum in length. The whole surface is most thickly clothed with
minute spines, which are not visible when the specimen is dry; I think
it probable that they may sometimes all drop off before a new period of
exuviation. The peduncle does not (at least in the specimens which I
have examined, which were grouped in a bunch) taper at the lower end to
a point; and after careful examination, I feel sure that the cement does
not debouch from several successively formed orifices, as in _S.
vulgare_ and as in some Pollicipes, but only from the two original
orifices in the prehensile antennæ of the larva. In these latter organs,
the sucking disc is hoof-like and pointed, and is narrower than the
basal segment. The ultimate segment has on its inner side (supposing
this segment stretched straight forwards,) a notch or step bearing at
least three spines. The proportions of the different parts differ
slightly from those in _S. vulgare_; but, as I shall hereafter have to
give all the measurements, I do not think them worth repeating here. In
the one large group of specimens examined by me, in Mr. Cuming’s
possession, all were attached symmetrically to the coralline, as in the
case of _S. vulgare_, capitulum upwards, and their carinas outwards.
_Length_ of capitulum about three quarters of an inch; width about half
an inch; entire length, with peduncle, a little more than one inch.
The _Mouth_ is placed far from the adductor muscle.
_Labrum_, with its basal margin much produced; upper part highly
bullate, forming a rounded projection equalling the longitudinal axis of
the rest of the mouth; crest without any teeth.
_Palpi_, triangular, with the two margins, thickly clothed with
bristles; on each side of the mouth, near where the palpi are united to
the mandibles, there is a slight, orbicular, shield-like swelling.
The _Mandibles_ (Pl. X, fig. 3) have nine or ten very unequal teeth,
with the inferior angle rather broad and pectinated; of these, there are
four main teeth, of which the second is always the smallest, and between
the four, one or two small teeth are interpolated; so that the total
number is either nine or ten, and often varies on the two sides of the
same individual, as likewise does the shape of the inferior angle.
_Maxillæ_, with the edge nearly half as long as that of the mandibles,
supporting from seventeen to twenty pairs of spines; the upper pair is
only slightly larger than the others; a part near the inferior angle
projects slightly beyond the rest of the nearly straight edge. The
apodeme, at its base or point of origin, is unusually broad and flat.
_Outer Maxillæ_, large and triangular. The inner margin is slightly
concave, and continuously covered with short spines. The outer margin is
bilobed, as in _S. vulgare_, with the basal part supporting a great tuft
of long bristles, of which the greater number turn outwards, and almost
cover the olfactory orifices. The latter are slightly prominent, placed
some way apart from each other, with the above-mentioned tufts of
bristles between them. All the spines of the trophi are in some degree
doubly serrated.
_Cirri._--The first pair is seated rather far from the second pair, and
the prosoma being little developed, the shape of the body nearly
resembles that of _S. vulgare_. The posterior cirri are elongated, very
little curled, with the segments much flattened, not at all protuberant,
bearing from five to seven pair of long serrated spines, with a few
small spines in an exterior row; between each pair there is a very
minute tuft of small bristles; the upper lateral rim of each segment is
toothed with small spines; spines of the dorsal tufts, long, serrated.
_First pair_, elongated, having numerous segments, namely, seventeen,
whilst the sixth pair in the same individual had only twenty-one
segments; rami nearly equal; segments short, nearly cylindrical, thickly
clothed with long serrated spines. The _second_ and _third_ pair are
nearly equal in length; they have their anterior rami slightly thicker
than their posterior rami, both being much more thickly clothed with
spines, than are the three posterior pair of cirri. Pedicels, rather
short, with their inner edges not forming a projection, as in _S.
vulgare_.
_Caudal Appendages_ (Pl. X, fig. 20), uni-articulate, flat, rounded at
their ends and moderately long; clothed most thickly, like brushes, with
very fine bristles, which latter are serrated, and are longer than the
appendages themselves.
_Penis_, of small size, narrow, pointed, and thickly clothed with
delicate hairs; in length equalling only one fourth of the sixth cirrus.
_Ovigerous Fræna_, small, semicircular; entire edge thickly covered with
glands. Ovarian tubes, within the peduncle, fully developed as usual.
_Affinities._--This species differs from all the others in the absence
of calcareous scales on the peduncle; but it has no other character
which at all justifies its generic separation. In the shape of the scuta
and carina it comes nearest to _S. vulgare_. Taking all the characters
together, it is scarcely possible to say to which of the other species
it is most closely allied, having close affinities with all. In the
entire structure, however, of the Complemental Male, immediately to be
described, this species certainly comes nearer to _S. villosum_ than to
any other species. I may add, that in _S. villosum_ the latera are
almost rudimentary, and therefore tend to disappear, whereas in _S.
Peronii_ it is the calcareous scales on the peduncle which have actually
disappeared.
COMPLEMENTAL MALE. Pl. VI, fig. 3.
I examined, owing to the great kindness of Mr. Cunning, six dry
specimens of the hermaphrodite _S. Peronii_, from Swan River, and one in
spirits from another locality, in the British Museum. Out of these seven
specimens, only three appeared to have had parasites attached to them,
and these I infer, from reasons to be more fully given at the end of the
genus, are Complemental Males. One of the three specimens, however, had
two males close together. These parasites were firmly cemented to the
integument of the hermaphrodite, in a fold, in a central line between
the scuta, a little below (the animal being in the position in which it
is figured) the adductor scutorum muscle, and therefore some way below
the umbones of these valves. When the scuta are closed, the parasites,
from their small size, are enclosed and protected. In every detail of
structure, they are obviously pedunculated Cirripedia.
The _Capitulum_ (Pl. VI, fig. 3) has six valves; namely, a pair of scuta
and of terga, a carina, and a rostrum, all united by finely-villose
membrane, furnished near the orifice with some much longer and thicker
spines. The capitulum is truncated in a remarkable manner, the orifice
not being, as in the hermaphrodite, in the same line with the peduncle,
but almost transverse to it, and therefore almost parallel to the
surface of attachment. The largest specimen measured transversely,
through the scuta and terga, was 30/1000ths of an inch in breadth;
another was only 26/1000ths to 27/1000ths: this latter specimen,
measured longitudinally, from the base of the carina to the tips of the
terga, was 15/1000ths of an inch. A scutum of the largest specimen was
17/1000ths in length. The scuta and terga are broadly oval, with the
primordial valves very plain at their upper ends. I may here mention,
that in a central line between the scuta, I observed the _apparently_
single, minute, black eye, as in ordinary Cirripedia.
The _Carina_ is straight, triangular, and internally slightly concave;
its basal margin descends far below the basal points of the terga.
The _Rostrum_ is shorter, and internally more concave than the carina: I
believe it projects more abruptly outwards than is represented in the
figure.
The _Peduncle_ commences some little way below the scuta: it is narrow
and very short: it is finely villose: it is lined by delicate transverse
striæ-less muscles, within which there are the usual stronger,
longitudinal muscles. The base is flat and truncated. I examined, and
carefully compared, the prehensile antennæ with those of the
hermaphrodite, and found every part and every measurement the same. The
full importance of this identity will hereafter be more fully insisted
on. The antennæ are represented of their proper proportional size in
fig. 3.
_Mouth._--The labrum, as in the hermaphrodite, is highly bullate, and
far removed from the adductor scutorum muscle. The _Palpi_ are small and
triangular, with their blunt apices clothed with a very few scattered
bristles.
_Mandibles_, with only three teeth, and the lower angle minute, slightly
pectinated; the first tooth is distant from the second, and larger than
it. Width of the whole organ, .0021 of an inch.
_Maxillæ_, bearing only a few spines, furnished with a long apodeme;
beneath the upper large pair there is a notch, under which there are two
spines of considerable size and a small tuft of fine bristles; width
.001 of an inch, and therefore only 1/16th of the size of the same organ
in the hermaphrodite: the relative sizes of the maxillæ and mandibles
are the same in the male and hermaphrodite.
_Outer Maxillæ_ blunt, triangular, with a few thinly-scattered bristles
on the inner face; those on the outside being longer.
_Cirri._--The First pair is far removed from the second; the rami are
very short, barely exceeding the pedicel in length; they are formed of
only four segments, each bearing a pair of spines; but on the end of the
terminal segment, there are three spines, of which the central one is
very long. Second pair also short. In the sixth pair there are five or
six elongated segments, each bearing three pair of long spines; dorsal
tufts large. The cirri are furnished with transversely-striated muscles.
The _Caudal Appendages_ exist as two very minute plates, with a few
bristles at their apices.
The _Penis_ is not acuminated, with four bristles at the end; it is
short, equalling only the lower segment of the pedicel of the sixth
cirrus. In the one specimen preserved in spirits, I unfortunately
omitted to search for the vesiculæ seminales; I cannot doubt that such
existed, but it would have been important to have ascertained whether
they contained spermatozoa. I made out, most distinctly, that there was
no trace of ovarian tubes within the peduncle; and my assertion may be
believed when I state, that I traced the two much finer and more
transparent cement-ducts, from the prehensile antennæ up to the body of
the animal: in Lepas I have _repeatedly_ detected, with ease, the
ovarian tubes within the peduncle, before the calcification of the
valves had even commenced, and therefore at a much earlier period of
growth than in these parasites. Consequently I am prepared to affirm,
that these parasites are not females, but that, as far as can be judged,
from external organs, they are exclusively males.
_Concluding Remarks._--In comparing the capitulum of the hermaphrodite
with that of the complemental male (Pl. VI, figs. 6 and 3), we must be
struck with the differences in their shape, in the number, relative
sizes, and forms of the several valves. It should, however, be borne in
mind, that the scuta and carina in the hermaphrodite at first grow
exclusively downwards; so that if we remove the upper portions
subsequently added, the difference in shape in these valves is not so
great as it at first appears. The rostrum in the male is of much larger
relative size; whilst of the upper latera there is not a trace, although
in the hermaphrodite these valves are larger than the rostrum. The
terga, compared with those of the hermaphrodite, differ more essentially
than do the other valves; and the manner in which the primordial valves
project, shows that from the first commencement of calcification, the
lines of growth have followed an unusual course. The great breadth and
shortness of the terga is evidently related to the shortening of the
whole capitulum, and the transverse position of the orifice; and this
shortening of the capitulum, no doubt, is rendered necessary for its
reception and protection within the shallow furrow between the scuta of
the hermaphrodite. Finally, if we compare the internal parts of the
hermaphrodite and male, the differences are considerable, though partly
to be accounted for by the youth of the latter: the form and position of
the labrum, and the distance between the first and second pair of cirri,
is the same in both; but the mandibles and maxillæ differ considerably.
To put the case as I have before done, if a specimen of one of these
parasites had been brought to me to class without any information of its
habits,--the downward direction of growth in all the valves, the
presence of a rostrum, the villose outer integument, all the details of
the prehensile antennæ, the form of the animal’s body, and the position
of the labrum, would have convinced me that, though a quite new genus,
it ought to have stood close to Scalpellum, and nearer to it than to
Ibla.
6. SCALPELLUM VILLOSUM. Pl. VI, fig. 8.
POLLICIPES VILLOSUS on Plate (TOMENTOSUS in text). _Leach._
Encyclop. Brit., Suppl., vol. iii, 1824, Pl. lvii.
---- VILLOSUS.[59] _G. B. Sowerby._ Genera of Shells, Pollicipes,
fig. 3, 1826.
CALANTICA HOMII. _J. E. Gray._ Annals of Phil., vol. x, p. 100,
1825.
[59] As Mr. Sowerby has adopted the name _villosus_, I have
followed him; though as _tomentosus_ is used through some mistake
by Leach in the text, both names have equal claims as far as
priority is concerned.
In Lamarck, ‘Animaux Sans. Vert.,’ the _P. villosus_ of Sowerby
is made synonymous with _Anatifa villosa_ of Brugière, which is
certainly incorrect, although the _A. villosa_ of this latter
author is not positively known.
_S. (Herm.) valvis 14: sub-rostro præsente: carinâ pæne rectâ: laterum
paribus tribus; pari superiore triangulo._
(Herm.) Capitulum with 14 valves: sub-rostrum present: carina nearly
straight: three pair of latera; upper latera triangular.
_Mandibles_ with four teeth, of which the second is the smallest:
maxillæ with a projection near the inferior angle: no caudal appendage.
COMPLEMENTAL MALE, attached externally between the scuta, below the
adductor muscle; pedunculated; capitulum formed of six valves, with the
carina not descending much below the basal angles of the terga: mouth
and cirri prehensile.
Eastern Seas[60] (?) attached to shells and rocks. Mus. Brit.;
College of Surgeons; Cuming.
[60] No habitat is attached to any of these specimens; but Mr.
Sowerby informs me that he has seen specimens attached to the
_Modiola albicostata_ of Lamarck, which shell is said by the
latter author to be found in the seas of India, Timor, and New
Holland.
HERMAPHRODITE.
_Capitulum_ with fourteen valves, consisting of a pair of scuta and of
terga, a carina, (which five valves are much larger than the others,) a
rostrum, sub-rostrum, sub-carina, and three pair of small latera. All
the valves are covered by membrane, as are the calcareous scales on the
peduncle; and this membrane everywhere is densely clothed with spines.
The upper valves are not very thick; they stand rather close together.
The eight valves of the lower whorl are more solid, and are placed far
apart; they are small, tending to become rudimentary. None of the valves
are added to at their upper ends, in which respect this species differs
remarkably from the others of the genus, and approaches in character to
Pollicipes.
_Scuta_, with a deep hollow for the adductor muscle, triangular, with
the basal margin elongated, and protuberant.
_Terga_, large, flat, triangular, basal point blunt, with the carinal
margin slightly hollowed out, and the scutal margin protuberant. Apex
solid.
_Carina_, rather longer than the terga, straight, gradually widening
from the upper to the basal end, deeply concave. In young specimens the
upper part is slightly bowed inwards. Apex solid.
_Sub-carina_, with the inner surface crescent-shaped; the umbo points
transversely outwards; in width it exceeds the largest of the latera.
_Rostrum_, triangular, internally (fig. 8 _a_) concave; basal margin
slightly hollowed out, and deeply notched; rather less in width than the
carina; short, with the umbo pointing upwards and outwards. In young
specimens the apex curves a little inwards.
_Sub-rostrum_, with the inner surface transversely elongated (fig. 8
_b_), slightly crescent-shaped, about two thirds as wide as the rostrum.
The apex points transversely outwards.
_Latera_, three pair; the middle pair apparently corresponds with the
upper latera of the other species of the genus. The two other pair of
latera, together with the rostrum and sub-carina, form a whorl. The
sub-rostrum lies by itself, a little beneath this whorl. The latera are
smaller than the rostrum or the sub-carina. They are placed far distant
from each other; their inner surfaces are triangular; their umbones
point upwards; the rostral pair is smaller than the other two pair,
which are of equal size. The exact position of the rostral latus
differed on the two sides of the specimen examined; apparently its
normal position is at the baso-lateral angle of the scuta.
_Peduncle_, wide at the summit, longer than the capitulum; calcified
scales small, not arranged very regularly; flattened, spindle-shaped,
rather far separated from each other; imbedded in membrane, so that even
their summits are rarely uncovered. The surface of the membrane is
thickly clothed with spines, which are strong, thick, yellow, pointed,
and furnished with large tubuli running to the underlying corium. These
spines are arranged in groups of from three or four, to five or six.
Besides these larger spines, the whole surface is villose with very
minute colourless spines, not above 1/20th of the length of the larger
ones. The surface of attachment is broad. This species, not being
symmetrically attached to a coralline, the peduncle does not curve, as
in most of the other species, towards the rostrum.
The capitulum is above half an inch in length.
_Mouth._--The labrum is much produced downwards, but yet the mouth is
not very far distant from the adductor muscle: the upper part is
bullate, forming a small overhanging point, and in longitudinal diameter
equals the rest of the mouth. _Palpi_ blunt.
_Mandibles_ with four teeth, strong, short, thick, the second tooth much
smaller than the others; inferior angle broad, pectinated.
_Maxillæ_ with a long, rather sinuous edge, which, near the inferior
angle, has a narrow projecting point, bearing rather finer spines; there
is, also, apparently, a very minute tuft of small spines close under the
two large upper spines: there are, altogether, about twenty pair of
spines, without counting the smaller ones.
_Outer Maxillæ_, with the inner edge slightly concave, continuously
covered with bristles; exteriorly, with a prominence covered with longer
bristles. Olfactory orifices prominent, protected by a slight punctured
swelling between the bases of the first pair of cirri.
_Cirri._--Prosoma moderately developed; first pair of cirri rather far
removed from the second pair. The segments of the three posterior pair
are not elongated, short, slightly protuberant in front, bearing four or
five pairs of strong spines; a little below each pair, there is an
intermediate tuft of very fine straight bristles, of which the upper
tuft is the largest; on the lateral upper rims there are some short,
strong spines; dorsal tufts rather small and thick; spines all more or
less serrated, especially on the broad basal segments of the three
anterior cirri. Pedicels of the cirri not particularly protuberant in
front. First cirrus with rami, slightly unequal in length; not short;
basal segments much thicker and more protuberant than the upper
segments. Second cirrus; anterior ramus with six or seven basal segments
highly protuberant, and crowded with spines; posterior ramus with about
six segments, similarly characterised. Third cirrus with the anterior
ramus having six, and the posterior ramus five segments, also similarly
characterised.
_Caudal Appendages_ absent, there being only a slight swelling on each
side of the anus.
The _oesophagus_ runs parallel to the labrum, and enters obliquely the
summit of the stomach, which is destitute of cæca: the biliary envelope
is longitudinally plicated.
There are no _Filamentary Appendages_.
_Testes_ large, branched like a stag’s horns, attached in a sheet to the
ventral surface of the stomach: the vesiculæ seminales enter the
prosoma, and have their reflexed ends not very blunt. The _Penis_ is
rather narrow, with the terminal half plainly ringed, and bearing tufts
of fine bristles arranged in circles, one tuft below the other; on the
basal half there are only a few scattered minute bristles.
_Affinities._--In the downward growth of all the valves, in the presence
of a sub-rostrum, in the shape of the scuta, carina, and more especially
of the triangular latera, in the form of the peduncle, with its
irregularly-scattered calcified scales, in the shape of the animal’s
body, in the structure both of the mandibles and maxillæ, in the
arrangement of the spines, both on the anterior and posterior cirri,
_Scalpellum villosum_ most closely resembles, or rather is identical
with, Pollicipes. Had it not been for the formation of the valves
forming the capitulum, and from the presence of Complemental Males, I
should have placed this species alongside of _Pollicipes spinosus_ and
_sertus_. In not having caudal appendages, _S. villosum_ differs from
all the species of Scalpellum and Pollicipes; but this organ is variable
to an unusual degree in Pollicipes.
COMPLEMENTAL MALE. Pl. VI, fig. 4.
From the kindness of Professor Owen, Mr. Gray, and Mr. Cuming, I have
been enabled to examine six specimens of this species; and on two of
them I found Complemental males. They were attached in the same position
as in _S. Peronii_; namely, beneath the adductor muscle, in the fold
between the scuta, so as to be protected by the latter when closed. This
parasite is six-valved, and has a close general resemblance with that of
_S. Peronii_, but differs in very many points of detail. It is
represented of the natural size at _á_ fig. 4. The capitulum is
43/1000ths of an inch, measured across the scuta and terga; and the same
measured from the base of the carina to the top of the capitulum; hence
it is broader, by a quarter of the above measurement, and considerably
higher than the male of _S. Peronii_. From the capitulum being higher,
that is, not so much truncated, the orifice is placed more obliquely.
The membrane connecting the valves is finely villose, and is besides
furnished with spines, conspicuously thicker and longer than those on
the male _S. Peronii_. The scuta and terga are much more elongated, a
scutum being here 35/1000ths of an inch in length. The carina descends
only just below the basal points of the terga, instead of far below
them. The rostrum is a little broader and more arched than the carina;
it is 2/1000ths in length, and therefore more than two thirds of the
length of the carina, the latter being 28/1000ths of an inch from the
apex to the basal margin. The primordial valves, with the usual
hexagonal tissue, are seated on the tips of the scuta, terga, and
carina, but not on the rostrum; so that these valves follow the same law
of development, as in the ordinary and hermaphrodite form of Scalpellum.
The scuta (_a_, fig. 4, greatly enlarged), the terga (_b_), and carina
(_c_) of the male, resemble the same valves in the hermaphrodite, much
more closely than do these valves in the male and hermaphrodite _S.
Peronii_. The rostrum has not its basal margin hollowed out, and is very
much larger relatively to the carina, than in the hermaphrodite. The
large relative size of the rostrum in the complemental male both of this
species and of _S. Peronii_, is a remarkable character, which I can in
no way account for.