genera, there are, I conceive, no grounds for dividing the Lepadidæ into
sub-families, as has been proposed by some authors, who have trusted
exclusively to external characters. In establishing the eleven genera in
the Lepadidæ, no one part or set of organs affords sufficient diagnostic
characters: the number of the valves is the most obvious, and one of the
most useful characters, but it fails when the valves are nearly
rudimentary, and when they are numerous: the direction of their lines of
growth is more important, and fails to be characteristic only in
Scalpellum: with the same exception, the presence or abscence of
calcified or horny scales on the peduncle is a good generic character.
For this same end, the shape of the scuta and carina, but not of the
other valves, comes into play. In three genera, the presence of
filamentary appendages on the animal’s body is generic; in Pollicipes,
however, they are found only on three out of the six species. The number
of teeth in the mandibles, and the shape of the maxillæ, often prove
serviceable for this end; as does more generally the presence of caudal
appendages, and whether they be naked or spinose, uniarticulate or
multiarticulate; in Pollicipes alone this part is variable, being
uni-and multi-articulate; and in one species of Scalpellum they are
absent, though present in all the others. The shape of the body, the
absence or presence of teeth on the labrum, the inner edge of the outer
maxillæ being notched or straight, the prominence of the olfactory
orifices, the arrangement of the spines on the cirri, and the number and
form of their segments, are only of specific value.
Comparing the pedunculated and sessile Cirripedes, it is, I think,
impossible to assign them a higher rank than that of Families. The chief
difference between them consists, in the Lepadidæ, in the presence of
three layers of striæ-less muscles, longitudinal, transverse and
oblique, continuously surrounding the peduncle, but not specially
attached to the scuta and terga; and on the other hand, in the
Balanidæ, of five longitudinal bundles of voluntary muscles, with
transverse striæ, fixed to the scuta and terga, and giving them powers
of independent movement. In the Lepadidæ, the lower valves, or when such
are absent, the membranous walls of the capitulum, move with the scuta
and terga when opened or shut; and the lower part of the capitulum is
separated by a moveable peduncle from the surface of attachment; in the
sessile Cirripedes, the lower valves are firmly united together into an
immovable ring, fixed immovably on the surface of attachment. I will not
compare the softer parts, such as the cirri and trophi, of the Lepadidæ
with those of the Balanidæ, as my examination of this latter family is
not fully completed: I will only remark, that there is a very close
general resemblance, more especially with the sub-family Chthamalinæ.
_Geographical Range; Habitats._--The Pedunculated Cirripedes extend over
the whole world; and most of the individual species have large ranges,
more especially, as might have been expected, those attached to floating
objects; excepting these latter, the greater number inhabit the warmer
temperate, and tropical seas. Of those attached to fixed objects, or to
littoral animals, it is rare to find more than three or four species in
the same locality. On the shores of Europe I know of only three, viz., a
Scalpellum, Pollicipes, and Alepas. At Madeira (owing to the admirable
researches of the Rev. R. T. Lowe), two Pæcilasmas, a Dichelaspis, and
an Oxynaspis are known. In New Zealand, there are two Pollicipes and an
Alepas, and, perhaps, a fourth form. From the Philippine Archipelago, in
the great collection made by Mr. Cuming, there are a Pæcilasma, an Ibla,
a Scalpellum, Pollicipes, and Lithotrya. Of all the Lepadidæ, nearly
half are attached to floating objects, or to animals which are able to
change their positions; the other half are generally attached to fixed
organic or inorganic bodies, and more frequently to the former than to
the latter. Most of the species of Scalpellum are inhabitants of deep
water; on the other hand, most of Pollicipes,[21] of Ibla, and Lithotrya
are littoral forms. The species of Lithotrya have the power of
excavating burrows in calcareous rocks, shells, and corals; and the
singular manner in which this is effected, is described under that
genus. Anelasma has its sub-globular peduncle deeply embedded in the
flesh of Northern Sharks; and I have seen instances of the basal end of
the peduncle of _Conchoderma aurita_, being sunk into the skin of
Cetacea; in the same way the point of the peduncle in the male of Ibla,
is generally deeply embedded in the sack of the female. I believe in all
these cases, the cementing substance affects and injures the corium or
true skin of the animal on which the creature is parasitic, whilst the
surrounding parts, being not injured, continue to grow upwards, thus
causing the partial embedment of the Cirripede. In the case of Anelasma,
we have growth at the end of the peduncle, and consequently downward
pressure, and this may possibly cause absorption to take place in the
skin of the shark at the spot pressed on.
[21] I am informed by Mr. L. Reeve that _Pollicipes mitella_ is
eaten on the coast of China; and Ellis states (‘Phil. Trans.,’
1758) that this is the case with _P. cornucopia_ on the shores of
Brittany. It is well known that the gigantic _Balanus psittacus_
on the Chilian coast, is sought after as a delicacy; and I am
assured, by Mr. Cuming, that it deserves its reputation.
_Geological History._--Having treated this subject at length, in the
volume of the Palæontographical Society for 1851, I will not here enter
on it: I will only remark, that the Lepadidæ or Pedunculated Cirripedes
are much more ancient, according to our present state of knowledge, than
the Balanidæ. The former seem to have been at their culminant point
during the Cretaceous Period, when many species of Scalpellum and
Pollicipes, and a singular new genus, Loricula, existed; Pollicipes is
the oldest genus, having been found in the Lower Oolite, and, perhaps,
even in the Lias. The fossil species do not appear to have differed
widely from existing forms.
_Genus_--LEPAS. Plate I.
LEPAS. _Linnæus._[22] Systema Naturæ, 1767.
ANATIFA. _Brugière._[23] Encyclop. Method. (des Vers), 1789.
ANATIFERA. (_Lister_) et plerumque Auctorum Anglicorum.
PENTALASMIS. (_Hill._) _Leach._ Journal de Physique, July, 1817.
PENTALEPAS. _De Blainville._ Dict. des Sci. Nat., 1824.
DOSIMA. _J. E. Gray._ Annals of Philosophy, vol. x, 1825.
[22] Linnæus, as is well known, included under this genus both
the pedunculated and sessile Cirripedes. According to the rules
of the British Association, the name Lepas must be retained for
part of the genus; and as the sessile division was named Balanus,
by Lister and Hill, even before the invention of the binomial
system, and subsequently, in 1778, by Da Costa, and again, in
1789, by Brugière, there can be no question that Lepas must be
applied to the pedunculated section of the genus. In this
instance it is particularly desirable to recur to the Linnean
name, as no other name has been _generally_ adopted. Had not
Lister and Sir J. Hill published before the binomial system,
their names of Anatifera and Pentalasmis would have had prior
claims to Lepas.
[23] The date of this publication is almost universally given as
1792, apparently caused by an error in the title-page of the
First Part, which has consequently been cancelled. The First Part
contains Anatifa and Balanus, and was published in 1789. The
Second Part was published in 1792, and has a corrected title-page
for the whole _volume_.
_Valvæ 5, approximatæ: carina sursùm inter terga extensa, deorsùm aut
furcâ infossâ aut disco externo terminata: scuta subtriangula, umbonibus
ad angulum rostralem positis._
Valves 5, approximate: carina extending up between the terga,
terminating downwards in an embedded fork, or in an external disc: scuta
sub-triangular, with their umbones at the rostral angle.
Filaments seated beneath the basal articulation of the first cirri;
mandibles with five teeth; maxillæ step-formed; caudal appendages
uniarticulate, smooth.
_Distribution._--Mundane; attached to floating objects.
_Description._--Capitulum flattened, sub-triangular, composed of five
approximate valves. The valves are either moderately thick and
translucent, or very thin and transparent; and hence, though themselves
colourless, they are often coloured by the underlying corium. Their
surfaces are either smooth and polished, or striated, or furrowed, and
sometimes pectinated. They are not subject to disintegration; they are
generally naked, except on the borders, where they are coated, and held
together by membrane; in _L. fascicularis_, however, the valves are
covered with thin membrane, bearing very minute spines. The manner of
growth of the valves will be best described under each. All the valves,
even in the same species, are subject to considerable variation in
shape, more especially the terga.
_Scuta._--These valves are sub-triangular in outline, with the basal
margin straight and rather short; and with occludent and tergo-carinal
margins more or less protuberant; in _L. fascicularis_, however, the
basal (Pl. I, fig. 6), and occludent margins are slightly reflexed and
prominent. A ridge, generally runs from the umbo to the upper point.
Internally, there is no conspicuous pit for the adductor muscle; under
the umbones, there is generally either on both valves, or only on the
right-hand side (Pl. I, fig. 1 _c_), a small calcareous projection or
tooth, of variable size and shape, even in the same species; it is
generally largest on the right-hand valve; these teeth at first sight
appear to form a hinge, uniting the opposite scuta at their umbones, but
this is not really the case, and their use appears to be only to give
attachment to the membrane uniting the valves together, and to the
peduncle. The basal margin is internally strengthened by a calcified
rim, more or less developed. The umbones (and primordial valves when
distinguishable,) are seated at the rostral angles; during growth the
basal margin is not added to, and the occludent margin only to small
extent; hence the main growth of the valve is at the upper end, and
along the carina-tergal margin. In _L. fascicularis_, however, the basal
reflexed margin is slightly added to beneath the umbo.
_Terga_,--flat, small compared with the scuta, usually of an irregular
quadrilateral figure, with the two upper or occludent margins very
short, in proportion to the two (carinal and scutal) lower margins; all
the margins are nearly straight. The two occludent margins, generally
meet each other at about right angles, forming a small triangular
projection; in _L. fascicularis_, however, the occludent margin is
formed by a single, slightly curved line. The umbones (and primordial
valves when distinguishable) are not seated at the uppermost point, but
at the angle where the carinal margin unites to the upper of the two
occludent margins: during growth the terga are added to, both on the
occludent and on the scutal margins, and slightly along the carinal
margin; hence their growth is unequally _quaqua-versal_, except at one
angle of the irregular quadrilateral figure.
_Carina._--This is always very narrow and curved, concave within, often
carinated and barbed exteriorly; it extends upwards between the terga
for one half or two thirds of their length: at the lower extremity it
ends (with the exception of _L. fascicularis_), in a small fork (Pl. I,
fig. 1, _a_, _b_) rectangularly inflected and embedded in the membrane,
beneath the basal margin of the scuta. From comparing this lower part of
the carina in _L. australis_ (fig. 5 _a_), with the same part in some of
the species of the allied genus Pæcilasma, it would appear that the fork
is formed by an oblong disc, more and more notched at the end, and with
the rim between the two points more or less folded backwards:
conformably with this view, in very young specimens of _L. australis_,
instead of a large and sharp fork, there is a small disc. The only use
of the fork appears to be to give firm attachment to the membrane
uniting the valves and peduncle. In _L. fascicularis_, instead of a
fork, there is a broad, oblong disc (figs. 6, 6 _a_), rectangularly
inflected; it is much longer than the fork, in proportion to the upper
part of the carina; the disc is not more deeply embedded than the upper
part. The umbo (and primordial valve when distinguishable,) of the
carina is seated just above the embedded fork (or disc in _L.
fascicularis_), at the point where the inflection takes place; hence the
main growth of the carina is upwards,--the fork, however, being of
course, likewise added to at its point: in _L. fascicularis_, the growth
is both upwards and downwards.
_Peduncle and Attachment._--The peduncle is generally quite smooth:
though with a high power its surface may be seen to be studded with
minute beads, or larger discs, of yellowish and hard chitine; in the
young of _L. australis_, and I suspect of some other species, it is
covered with very minute spines. The peduncle in this genus attains its
greatest development. The cement-tissue debouches, I believe, only
through the functionless larval antennæ, except in one species, _L.
fascicularis_, in which a ball of this substance is formed in a most
peculiar manner round the peduncle (Pl. I, fig. 6), apparently for the
purpose of serving as a float, as will be presently described.
_Size and Colour._--The species of this genus are the largest of the
Pedunculata, with the exception of some Pollicipes: even in the smallest
species (_L. pectinata_), the capitulum sometimes attains a length of
about half an inch. The peduncle varies much in length in the same
species: in _L. anatifera_, it is occasionally above a foot long. The
colours of _L. anatifera_, _L. Hillii_, and _L. anserifera_, are very
bright and striking; the membrane bordering the valves and that round
the top of peduncle in two of the species, is of the brightest
scarlet-orange; the valves, owing to the underlying corium, are pale
blueish-grey, and the interspaces between them dark leaden-purple. The
cirri and trophi are generally dark purple or lead-colour.
_Filamentary Appendages._--These are attached to beneath the basal
articulation of first pair of cirri; they vary in the several species,
from one to five or six on each side, the lowest being always the
longest. Several of them are occupied by testes. In _L. pectinata_,
generally, not even one is developed. They are subject to great
variation in their proportional lengths, and in number, in the same
species. These organs have generally been considered to serve as
branchiæ; I see no reason to believe that they are more especially
designed for this end, than is the general surface of the body.
_Mouth._--The labrum is moderately bullate, the longitudinal diameter of
this part equalling about one third, or half of that of the rest of the
mouth. The palpi are moderately developed. The mandibles (Pl. X, fig. 5)
have five teeth with the inferior point either broad, or very narrow and
tooth-like. The maxillæ are step-formed (Pl. X, fig. 9); the first step
is sometimes indistinct and curved; and in _L. pectinata_, all the steps
vary much, and are more or less blended together. The outer maxillæ
(like those at Pl. X, fig. 16), are internally clothed continuously with
spines. The olfactory orifices are not at all prominent.
_Cirri._--The first pair is placed near the second pair, and is of
considerable length; the second has the anterior ramus thicker than the
posterior ramus, and the segments brush-like; the segments (Pl. X, fig.
26) of the four posterior cirri bear from four to six pair of long
spines, with a row of small intermediate spines: in the posterior cirri
of _L. australis_ the lateral rim spines are much developed; and in
those of _L. fascicularis_, the usual pairs of large spines are lost in
a broad triangular brush, formed by the increase of the lateral
marginal, and intermediate spines.
_Caudal Appendages_ (Pl. X, fig. 18 _b_), very small, either blunt or
pointed, and quite destitute of spines.
The prosoma is well developed. The stomach is surrounded in the upper
part by a circle of large branching cæca. The generative system is
highly developed; the testes coating the whole of the stomach, entering
the filamentary appendages and the pedicels of the cirri; the two
ovigerous lamellæ contain a vast number of ova; they are united to
rather large fræna, of which the sinuous margin supports either a
continuous row or separate tufts of glands.
_Distribution._--The species abound over the arctic, temperate and
tropical parts of the Atlantic, Indian and Pacific Oceans, and are
always, or nearly always, attached to floating objects, dead or alive.
The same species have enormous ranges; in proof of which I may mention
that of the six known species, five are found nearly all over the world,
including the British coast; and the one not found on our shores, the
_L. australis_, apparently inhabits the whole circumference of the
southern ocean.
_General Remarks and Affinities._--The first five species form a most
natural genus; they are often sufficiently difficult to be
distinguished, owing to their great variability. The sixth species (_L.
fascicularis_) differs to a slight extent in many respects from the
other species, and has considerable claims to be generically separated,
as has been proposed by Mr. Gray, under the name of Dosima; but as it is
identical in structure in all the more essential parts, I have not
thought fit to separate it. As far as external characters go, some of
the species of Pæcilasma have not stronger claims, than has _L.
fascicularis_, to be generically separated; and I at first retained them
altogether, but in drawing up this generic description, I found scarcely
a single observation applicable to both halves of the genus; hence I was
led to separate Lepas and Pæcilasma. If I had retained these two genera
together, I should have had, also, to include the species of Dichelaspis
and Oxynaspis; and even Scalpellum would have been separable only by the
number of its valves; this would obviously have been highly
inconvenient. Although some of the species of Pæcilasma so closely
resemble externally the species of Lepas, yet if we consider their
entire structure, we shall find that they are sufficiently distinct; as
indirect evidence of this, I may remark that Conchoderma (as defined in
this volume), includes two genera of most authors, and yet certainly
comes, if judged by its whole organisation, nearer to Lepas than does
Pæcilasma.
1. LEPAS ANATIFERA. Tab. I. fig. 1. (_var._)
L. ANATIFERA. _Linnæus._ Systema Naturæ, 1767.
ANATIFA vel ANATIFERA vel PENTALASMIS lævis[24], plerumque
auctorum.
---- ENGONATA (!).[25] _Conrad._ Journal Acad. Nat. Sc.
Philadelphia, vol. vii, 1837, p. 262, Pl. xx, fig. 15.
---- DENTATA (var.) _Brugière._ Encyclop. Meth. (des Vers), 1789.
PENTALASMIS DENTATUS (var.) _Brown._ Illust. Conch., Pl. lii, fig.
5.
ANATIFA . . . . . _Martin St. Ange._ Mem. sur l’organisation des
Cirripedes, 1835.
[24] As this, though the commonest species, has never been
defined, I give only a few synonyms and references, it being
quite impossible to distinguish, in any published description,
this species from _A. Hillii_ of Leach; this latter species I
recognise under this name only from having authentic specimens
from the British Museum, as Leach overlooked every one of the
real diagnostic characters.
[25] I have used, in conformity with botanists, the mark of
interjection, to show that I have seen an authentic specimen.
_L. valvis aut lævibus aut delicate striatis: è duobus scutis, dextro
solùm dente interno umbonali instructo; pedunculi parte superiore
fuscâ._
Valves smooth, or delicately striated. Right-hand scutum alone furnished
with an internal umbonal tooth: uppermost part of peduncle
dark-coloured.
Filaments, two on each side.
Var. (_a_). Fig. 1. Scuta and terga with one or more diagonal lines of
dark greenish-brown, square, slightly depressed marks.
Var. (_b_). (Fig. 1 _b._) Carina strongly barbed.
Extremely common; attached to floating timber, vessels,
sea-weed, bottles, &c., and to each other, in the Atlantic
Ocean, Mediterranean, West Indies, Indian Ocean, Philippine
Archipelago, Sandwich Islands, Bass’s Straits, Van Diemen’s
Land.
_General Appearance._--Valves white, more or less translucent and thick,
with a tinge of blueish-grey, from the underlying corium; sometimes
brownish cream-coloured, rarely with a tint of purple. Surfaces smooth,
with traces of very fine lines radiating from the umbones, sometimes
rather plain on the basal part of the scuta. Length in proportion to the
breadth of the capitulum variable, owing to the varying degree to which
the scuta and terga have their apices produced. _Scuta_ with the
occludent margin either considerably curved or nearly straight. The
internal tooth of the right-hand scutum, close to the umbo, varies in
size and form, being either pointed, square, or obliquely truncated on
either side, or it has a notch on the summit; internal basal rim of the
scuta either plainly developed or nearly absent. In many specimens (Pl.
I, fig. 1), on the scuta, or on the scuta and terga, (and sometimes more
on one side of the individual than on the other,) a nearly straight
line, running diagonally across the capitulum, of slight, quadrilateral
depressions, of a dirty greenish colour, with the edges blending away,
is either conspicuously developed, or can only just be discerned. These
marks increase in size from the umbones to the margins of the valves.
There are sometimes two or even three rows on the scuta. They are formed
by the retention of a portion of the chitine membrane, which is cast off
the rest of the surface; the margins of the valves are occasionally
notched slightly on the line of marks; there is no difference along this
line in the underlying corium. Specimens both with and without a barbed
carina are thus characterised. _Carina_; the interspace between the
carina and the scuta and terga is not wide. The carina exteriorly, is
either convex and smooth, or furnished with knobs or with extremely
sharp, long teeth (Pl. I, fig. 1 _b_); small specimens, with the
capitulum under half an inch in length, are generally most strongly
barbed.[26] Apex more or less acuminated; width and thickness variable;
sides strongly furrowed. Fork (fig. 1 _a_) generally less wide than the
widest upper part of the valve, with the two prongs diverging from each
other at less than a right angle; their sharpness and precise form
variable; rim between them reflexed (figs. 1 _a_ and _b_), making a
slight notch behind. _Peduncle_ smooth, wrinkled, length in proportion
to that of the capitulum varying, from barely equalling it, to six or
seven times as long. I have noticed a specimen including mature ova,
with a capitulum under half an inch long.
[26] Mr. W. Thompson found that 15 specimens, out of about 200,
attached to a vessel which came from New Orleans into Belfast,
had their carinas barbed.
_Filamentary Appendages_;--never more than two on each side, with
sometimes only one developed; of variable length; one seated on the
flank of the prosoma, under the first cirrus; the second close under the
basal articulation of this cirrus, on the posterior face of a slight
swelling: these appendages correspond with _g_ and _h_ in Fig. 4, Pl.
IX.
_Mouth._--Mandibles (Pl. IX, fig. 5), with, as usual, five teeth, all
pointing downwards. Maxillæ (Pl. IX, fig. 9), with the lower step of
variable width compared to the two upper steps. _Cirri_; posterior cirri
with segments (fig. 26) bearing six pair of spines; intermediate fine
spines rather long; first cirrus, anterior ramus longer by only about
two segments than the posterior ramus; second cirrus with anterior
ramus, with very broad transverse rows of bristles; spine-bearing
surfaces considerably protuberant; caudal prominences smooth, rounded.
_Size._--The largest specimen which I have seen had a capitulum two
inches in length; the longest, including the peduncle, was sixteen
inches.