sometimes strongly barbed; narrow above the fork, which latter is wider
than the widest upper part of the valve; prongs sharp, thin, diverging
at an angle of from 135° to 180°; the rim connecting the prongs not, or
only slightly, reflexed.
_Peduncle_, narrow, shorter than the capitulum.
_Filamentary Appendages_, none, or only one, short, obtuse projection on
each side, on the posterior face of the swelling under the first cirrus.
_Mouth._--Mandibles, with the inferior point produced into a single
pectinated tooth, rarely into two pectinated teeth; on one side of one
specimen, there were only four instead of five teeth. Palpi very narrow.
Maxillæ highly variable; they may be described as formed of five steps,
of which the two lower ones are generally united into a single one,
divided by a mere trace of a notch; or with the three lower steps
blended into an irregular, projecting surface, and with even the fourth
step indistinct. I have seen these two extreme forms on opposite sides
of the mouth of the same individual,--on one side the maxillæ being
regularly step-form, on the other the whole inferior part forming an
almost straight edge, standing high up above the first notch or step
which bears the two upper great spines.
_Cirri._--First pair rather far removed from the second pair, with the
longer ramus about three-fourths of the length of shorter ramus of
second cirrus; spine-bearing surfaces, hardly at all protuberant;
lateral marginal spines on the posterior cirri rather long; caudal
appendages smooth, rounded, extremely minute: penis very spinose.
_Size._--Capitulum in the largest specimen, six-tenths of an inch long;
only a few arrive at this size.
_Colours_, after having been kept in spirits,--sack and cirri,
especially first cirrus, clouded with pale purple; peduncle brownish;
valves appear blueish in specimens not long preserved, but in specimens
kept longer they become perfectly and delicately white.
_General Remarks._--Under the head of _L. anserifera_, I have made some
remarks on the diagnostic characters of this species. In the thinness of
the valves,--form of the carina, with the rim connecting the prongs
being not, or scarcely, reflexed,--and in the shortness and narrowness
of the peduncle, there is some approach to _L. australis_, and thence to
_L. fascicularis_. In the form of the maxillæ,--in one specimen having
the mandible on one side bearing only four teeth,--and in the frequent
absence of filamentary appendages, there is some approach to the genus
_Pæcilasma_; but there is no such approach in the characters derived
from the capitulum. We have seen that, as in so many other species of
this genus, most of the parts are variable, and this is the case to a
most unusual extent in the form of the maxillæ. Dr. Leach has attached
eight specific names to the specimens preserved in the British Museum.
5. LEPAS AUSTRALIS. Pl. I, fig. 5.
_L. valvis glabris, tenuibus, fragilibus; scutorum dentibus umbonalibus
utrinque internis; carinæ parte superiore latâ, planâ, suprâ furcam
valdè constrictâ; furcæ cruribus latis, planis, tenuibus, acuminatis,
intermedio margine non relexo._
Valves smooth, thin, brittle; scuta with internal umbonal teeth on both
sides. Carina with the upper part broad, flat; much constricted above
the fork, which has wide, flat, thin, pointed prongs, with the
intermediate rim not reflexed.
Filaments, two on each side.
Common on Laminariæ in the whole Antarctic Ocean: Bass’s
Straits, Van Diemen’s Land: Bay of Islands, New Zealand, lat.
35° S.: lat. 50° S., 172° W.: coast of Patagonia, lat. 45° S.:
attached to bottom of H. M. S. Beagle, lat. 50° S., Patagonia:
attached to a Nullipora, (I presume a drift piece,) British
Museum.
_General Appearance._--Capitulum rather obtuse and thick; valves thin,
brittle, approximate, either white and transparent, or dirty-brown and
opaque; or sometimes tinted internally with purple (perhaps the effects
of being preserved in spirits); surface plainly marked by lines of
growth, rarely marked with traces of lines radiating from the umbones.
_Scuta_ with teeth on both sides, nearly equal; internal basal rim
rather wide, sometimes furrowed; basal margin considerably curved
inwards. _Terga_ rather wide; basal angle blunt; angle formed by the two
occludent margins blunt and rounded. _Carina_ (fig. 5 _a_) with the apex
blunt, flat; the middle part generally very broad; much constricted
above the fork, where it is internally deeply concave, and externally
carinated; fork twice as broad as the broadest upper part of the valve;
with the prongs flat, broad, thin, pointed, diverging at about an angle
of 75°, with the intermediate rim not at all reflexed; the fork
generally not deeply imbedded in the chitine membrane of the peduncle,
so as to be quite easily visible externally; sometimes there is an
internal, transverse, depressed line on the fork. In young specimens,
with the capitulum about a quarter of an inch long, the fork of the
carina is not developed, the lower slightly inflected portion consisting
simply of an oval plate, twice as wide as the upper part. Until I had
carefully examined a perfect series, showing the gradual changes in this
part, I did not doubt that the young specimens formed a distinct
species, and named it accordingly: the shortness of the penis first made
me perceive that the specimens were immature. At this early age, I may
add, the filamentary appendages were not developed. _Peduncle_ either
quite short, or as long as the capitulum, close under which it is
considerably constricted all round.
_Filamentary Appendages._--Two on each side; one long, tapering, placed
on the prosoma (in one specimen represented by a mere knob), and the
second shorter, situated on the posterior margin of the swelling beneath
the first cirrus.
_Mouth._--Maxillæ, with three large spines at the upper angle, and with
the first step distinct, but narrow; mandibles with five teeth; in young
specimens the inferior point ends in a single spine; sides of the
supra-oral cavity very hairy; the membrane, forming the inner fold of
the labrum, yellow and thickened in the form of a spoon.
_Cirri._--In the posterior cirri there are, at the upper lateral edges
of the segments on _both_ sides, small spines; the segments in the first
cirrus, and in the broad anterior ramus of the second cirrus, are
hemispherically and considerably protuberant. Caudal appendages smooth.
_Size._--The largest specimen had a capitulum one inch long.
The _Colours_ (after having been long in spirit) of the valves have
already been given; sack and peduncle dirty yellowish-brown, with the
parts corresponding to the margins of the valves much darker brown, or
almost black; segments of the cirri clouded with dark brown; body and
pedicels of the cirri dirty yellowish. I have reason to believe that the
colours are totally different in living specimens.
_Monstrous Varieties._--Most of the specimens from lat. 50° S., on the
coast of Patagonia, were more or less deformed, with the successive
zones of growth overlapping each other, and forming coarse concentric
ridges. The carina in several specimens was laterally distorted.
I have already remarked that this species has some affinity to _L.
pectinata_; but it is much more closely related to _L. fascicularis_,
the affinity being clearly shown by the thinness and translucency of the
valves, their convexity, by the width and little acumination of the
upper part of the carina, by the width of the fork, and by its not being
deeply imbedded. In young specimens, moreover, before the fork is fully
developed, there is a remarkable similarity between the two species, in
the form of this lower part of the carina. Again, the narrowness and
inflection of the peduncle under the capitulum in _L. australis_, and
lastly, the lateral marginal spines on both sides of the segments of the
posterior cirri, all clearly indicate this same affinity to _L.
fascicularis_.
I believe this species is confined to the southern ocean; and perhaps
there represents _L. fascicularis_ of the northern and tropical seas. It
must, judging from the number of specimens brought home by Captain Sir
J. Ross, and from those previously in the British Museum, and from those
collected by myself, be a very common species.
6. LEPAS FASCICULARIS. Pl. I, fig. 6.
LEPAS FASCICULARIS. _Ellis_ and _Solander_. Zoophytes, 1786, Tab.
xv, fig. 5.
---- ---- _Montagu._ Test. Brit. Suppl., 1808, pp. 5, 164.
---- CYGNEA. _Spengler._ Skrifter Naturhist. Selbskabet, Bd. i,
1790, Tab. vi, fig. 8.
---- DILATA. _Donovan._ British Shells, 1804.
PENTALASMIS FASCICULARIS. _Brown._ Illust. Conch., 1844, Pl. li,
fig. 2.
---- SPIRULICOLA (!) et DONOVANI (!) _Leach._ Tuckey’s Congo
Expedit., p. 413, 1818.
ANATIFA VITREA. _Lamarck._ Animaux sans Vertebres.
DOSIMA FASCICULARIS. (!) _J. E. Gray._ Annals of Philosophy, vol.
x, 1825.
PENTALEPAS VITREA. _Lesson._ Voyage de la Coquille. Mollusca, Pl.
xvi, fig. 7, 1830.
ANATIFA OCEANICA (!) _Quoy_ et _Gaimard_. Voyage de l’Astrolabe,
Pl. xciii.
_L. valvis glabris, tenuibus, pellucidis; carinâ rectangulè flexâ, parte
inferiore in discum planum oblongum expansâ._
Valves smooth, thin, transparent; carina rectangularly bent, with the
lower part expanded into a flat oblong disc.
Filaments, five on each side; segments of the three posterior cirri with
triangular brushes of spines.
Var. (_Donovani_, of Leach.) Carina with the upper part flat,
spear-shaped, externally with a narrow central ridge.
Var. (_Villosa._ Pl. I, figs. 6 _b_, _c_.) Valves placed rather distant
from each other; carina extremely narrow, with the upper part of nearly
the same width throughout; terga with the lower part much acuminated;
body of animal finely villose.
Coasts of Great Britain and France; Baltic Sea, according to
Montagu Southern United States (from Agassiz); tropical Atlantic
Ocean; East-Indian Archipelago, off Borneo and Celebes; Pacific
Ocean, between the Sandwich and Mariana Archipelagos; New
Zealand: attached to fuci, Spirulæ Janthinæ, Velellas, often to
feathers and cork; often associated with the young of _L.
anserifera_, (var. _dilatata_,) and _L. pectinata_.
_General Appearance._--Capitulum highly variable in all its characters;
thick and broad in proportion to its length, but the breadth is
variable,--in some specimens, the capitulum being longer by one-fifth of
its total length than broad; in others, one-fifth broader than long.
Valves generally approximate; in some varieties, however, from the
narrowness of the carina and terga, the valves stand far apart, there
being an interval between the carina and scuta of nearly half the
breadth of the latter. Valves excessively thin, brittle, transparent,
colourless, smooth, but generally sinuous along the zones of growth,
which are conspicuous: valves generally covered throughout by thin
chitine membrane, which is thickly clothed, especially in the
interspaces between the valves, with minute spines, barely visible to
the naked eye. _Scuta_ with the lower part of the tergo-carinal margin
extremely protuberant; occludent margin, more or less, but slightly
reflexed, with a depressed line running from the umbo to the apex; basal
margin much reflexed, but to a variable extent and at a varying angle,
even up to a right angle,--an external rim or collar being thus formed.
There are no distinct _internal_ teeth, but the basal margin under the
umbones, is more or less distinctly produced into a rounded disc or
projection, which is generally not so much outwardly reflexed as the
rest of the basal margin: there is no distinct internal basal rim. The
primordial valves are generally visible, but they do not lie, as in all
other species, close to the basal margin, but a little above it,--the
lower reflexed portion having been subsequently developed. _Terga_ flat,
with the occludent margin slightly arched, and not, as in the foregoing
species, formed of two sides; apex bent towards the carina; width of the
lower half highly variable, owing to the varying extent to which the
scutal margin is hollowed out; in some specimens, the whole lower half
beneath the apex of the scuta is of nearly the same width throughout; in
other specimens this lower part is spear-shaped. The widest part of the
tergum either equals in width, or is only two-thirds of the width of the
widest part of the carina beneath its umbo. _Carina_ (Pl. I, fig. 6 _a_)
highly variable in shape, with the part above the umbo either
spear-shaped and slightly concave within, or nearly flat and furnished
with a central external ridge; or the upper part (fig. 6 _c_) is of
equal and extreme narrowness throughout, and deeply concave within,
appearing as if only the central ridge had been developed. The part
below the umbo, (answering to the fork in the foregoing species,) is
about one-third of the length of the whole valve, and generally twice as
wide as the upper part, but in the variety with the upper part of the
carina equally narrow throughout, the lower part is thrice as wide as
the upper; the disc, or lower part, is generally slightly concave
within, exteriorly either with or without a central ridge; basal margin
rounded; lateral margin more or less curved, according to the form of
the upper part. The disc is not more deeply imbedded in membrane than is
the upper part of the valve. The heel or umbo is either angular and
prominent, or rounded. In very young specimens the carina is simply
bowed, instead of being rectangularly bent.
_Peduncle_,--short, narrow, being abruptly inflected all round under the
basal edges of the capitulum; lower part of very variable shape, being
often suddenly contracted into a mere thread (fig. 6 _b_), which
sometimes widens again at the extreme end. The external membrane is very
thin, and is penetrated by the usual fine tubuli leading to the corium;
its surface is wrinkled and destitute of spines, or with extremely few.
The peduncle is often completely surrounded by a yellowish ball, (of
which I have seen specimens from the coast of England, and from off
Borneo,) sometimes half as wide as the capitulum, composed of very
tender, vesicular, structureless membrane, and of a pulpy substance:
perhaps the yellow colour may be owing to long immersion in spirits.
Some authors have supposed that the ball was the ovisac of the animal;
and for the first few minutes, deceived by the numerous included spores
of, as I believe, Bacillariæ, I thought that this was the case; others
have supposed that it consisted of some encrusting algæ or other foreign
organism; but it is, in reality, a most singular development of the
cement-tissue, which ordinarily serves to attach Cirripedes by their
bases to some extraneous object, but here surrounding that object and
the peduncle, gives buoyancy, by its vesicular structure, to the whole.
The membrane of the ball falls to pieces in caustic potash, differently
from the chitine membrane of the enclosed peduncle, and this shows that
there is some difference in composition from ordinary cement. The ball,
when cut in two, exhibits an obscure concentric structure. The whole is
excreted by the two cement-ducts, through two rows of orifices, one on
each side of the surrounded portion of the peduncle; and I actually
traced, in one case, the yellow pulpy substance coming out of the
cement-ducts. The upper apertures are in gradation larger than those
below them, and they stand a little further apart from each other; these
are figured as seen from the outside, much magnified, at Pl. I, fig. 6
_d_. I did not succeed in finding the cement-glands, but I followed the
ducts, of rather large size, running for a considerable distance as
usual along and within the longitudinal muscles of the peduncle. Nearly
opposite the uppermost aperture, on each side, the duct passes out
through the corium, and becomes laterally attached to the outer membrane
of the peduncle, at which point an aperture is formed (as in other
cases, by some unknown process), thus giving exit to the contents of the
duct. Beneath this upper aperture the duct runs down the peduncle,
between the corium and the outer membrane, till it comes to the next
aperture, to which it is also attached, and so on to all the lower ones;
but I believe no cement tissue continues to pass out through these
lower apertures. Beneath the lowest aperture the two ducts run into the
two prehensile antennæ of the larva, which, as usual, terminate the
peduncle. The antennæ are attached to some small foreign body in the
centre of the vesicular ball, by the usual tough, light brown,
transparent cement. The two upper apertures are nearly on a level with
the outside surface of the ball; and it was evident that as the animal
grows, new apertures are formed higher and higher up on the sides of the
peduncle, and that out of these, fresh vesicular membrane proceeds, and
grows over the old ball in a continuous layer. It appears that the
growth of the vesicular ball is not regular,--that it is not always
formed,--and that when formed the whole, or the lower part, sometimes
disintegrates and is washed away. As that portion of the peduncle which
is enclosed ceases to grow, and has its muscles absorbed, retaining only
the underlying corium, whereas the upper unenclosed portion, and
likewise, (as it appears) lower portions once enclosed but since
denuded, continue to increase in diameter, the peduncle, when the
vesicular ball is removed, often has the most irregular outline,
contracting suddenly into a mere thread, and then occasionally expanding
again at the basal point.
Frequently two or three specimens have their peduncles imbedded in one
common ball, of which there is a fine specimen in the College of
Surgeons (Pl. I, fig. 6), the ball being about one inch and a quarter in
diameter, with a slice cut off. In this specimen, it is seen that the
vesicular membrane proceeding from several individuals, unites to form
one more or less symmetrical whole, and that the original common object
of attachment is entirely hidden. Dr. Coates[29] gives a curious account
of the infinite number of specimens, through which he sailed during
several days, in the Southern Atlantic Ocean: the balls appeared like
bird’s eggs, and were mistaken for some fucus, which was supposed to
have encrusted the scales of the Velellæ, to which the Cirripede had
originally become attached. Several individuals had their peduncles
imbedded in the same ball, “which floated like a cork on the water.” As
this species grows into an unusually bulky animal, we here see a
beautiful and unique contrivance, in the cement forming a vesicular
membranous mass, serving as a buoy to float the individuals, which, when
young and light, were supported on the small objects to which they
originally had been cemented in the usual manner.
[29] Journal of the Acad. Nat. Sc., Philadelphia, vol. vi, p.
138, 1829.
_Filamentary Appendages._--Five on each side, of which four lie in pairs
at the base of the first cirrus (of these, only three are sometimes
developed), and one on the flank of the prosoma.
_Mouth._--Palpi much acuminated. Mandibles with five teeth; the first
not far remote from the second; inferior point rather broad and finely
pectinated. Maxillæ with two large, unequal, upper spines, and four
regular steps.
_Cirri._--Posterior cirri, with the upper parts of the segments slightly
protuberant; in young specimens, the spines can be seen to consist of
five pairs, placed in two converging lines in the upper half of each
segment, with numerous minute, latero-marginal, and intermediate little
bristles: in large specimens, all these latter have so increased in
number, that the normal five pair cannot be distinguished, and the front
of each segment is covered by a triangular thick brush of bristles, all
pointing in the same direction, thus giving a very unusual character to
the posterior cirri: the dorsal tuft on each segment consists of six or
seven large spines, with from one to three dozen fine ones. First cirrus
and anterior ramus of second cirrus with broad brushes of bristles. The
pedicels of all the cirri are thickly covered with bristles. _Caudal_
appendages smooth, with rounded summits.
_Penis_ very hairy: vesiculæ seminales purple, much convoluted, lying
within the prosoma; testes dendritic, scarcely enlarged at their
terminal points, purplish; ovigerous fræna large with sinuous margins,
the glandular beads being arranged in groups.
_Size._--The largest specimen (from the coast of Devonshire) had a
capitulum 1.6 of an inch long, and 1.2 broad, and of unusual thickness.
_Colours_, after having been in spirits: front surfaces of the segments
of the cirri and of the pedicels purple. In some specimens from off
Borneo, parts of the sack and the interspaces between the two scuta,
were of a fine purple. Montagu states, that the whole shell and body of
animal, when fresh, are pale blue, with the cirri spotted with brown.
_General Remarks._--The extreme variability of this species is
remarkable. In the College of Surgeons, there is a group of specimens
collected by Mr. Bennett, I believe, in the Atlantic, in which the
extreme narrowness of the carina and of the terga (Pl. I, fig. 6, _b_,
_c_) (with consequent wide spaces of membrane left between these
valves), led me, at first, to entertain no doubt, that it was quite a
distinct species, which was strengthened by finding that the whole
surface of the cirri were villose, with very minute spines; hence I
called this variety, _villosa_. On the closest examination, however, I
could detect no other differences, and the narrowness of the carina and
terga varied very considerably: moreover, in one of the specimens, which
was about intermediate in the form of its valves between this variety
and the common form, the surfaces of the cirri were not in the least
degree villose. Again, in some other specimens, the terga were as narrow
as in Mr. Bennett’s, whilst the carina had its usual outline.
In a var. (called by Leach, _P. Donovani_,) from the Atlantic, under the
Equator, the carina is remarkable from the extreme flatness of the upper
part, and from the presence of an exterior, narrow, central ridge. In
one specimen from Jersey, in the British Museum, the carina made an
extremely near approach to this same form.
_Affinities._--This species is certainly much the most distinct of any
in the genus, and Mr. Gray has proposed to separate it under the name of
Dosima; but considering the close similarity of the whole organisation
of the internal parts, together with the transitional characters
afforded by _L. australis_, I think the grounds for this separation are
not quite sufficient. I have remarked, under _L. australis_, on the
affinity between that and the present species. In the carina terminating
in a disc (though here not imbedded), there is some slight affinity to
_Pæcilasma eburnea_ and _crassa_, and markedly so in the arrangement of
the bristles on the posterior cirri. In the valves being covered with
villose membrane, and to a certain extent in the form of the carina and
of the occludent margin of the terga, and especially in the two rows of
cement-orifices in the peduncle, there is some affinity to Scalpellum.
PÆCILASMA. _Nov. Genus._[30] Plate II.
ANATIFA. _J. E. Gray._ Proc. Zoolog. Soc., 1848, p. 44.
TRILASMIS. _Hinds._ Voyage of the Sulphur. Mollusca, 1844.
[30] [Greek: Pokilos], various, and [Greek: elasma], plate or
valve. I have not been able to adopt Mr. Hinds’ name for this
genus, as it would be too glaringly incorrect to call a
five-valved species, a _Trilasmis_.
_Valvæ, 3, 5, aut 7, approximatæ: carina solùm ad basales apices
tergorum extensa, termino basali aut truncato aut in discum profunde
infossum producto: scuta pænè ovalia, umbonibus ad angulum rostralem
positis._