BALANUS LÆVIS. _Bruguière._ Encyclop. Meth. (1789), Pl. 164, fig.
1.[91]
---- DISCORS. _Ranzani._ Mem. di Storia Nat., 1820, Tab. 3, figs. 9
to 13.
---- COQUIMBENSIS. _G. B. Sowerby_, in Darwin's Geology of South
America (1846), Tab. 11, fig. 7.
[91] M. Deshayes, in his descriptions of the plates, considers this
figure, I have no doubt erroneously, as that of _B. perforatus_, of
Bruguière. The _B. Coquimbensis_ of Sowerby, is a different species
from the _B. Coquimbensis_, of Chenu, 'Illust. Conch.,' tab. 6,
which latter is unknown to me.
_Shell covered by brown membrane, or naked and white or pale purple;
orifice small; radii very narrow. Scutum with one or two deep
longitudinal furrows._
_Var._ nitidus (fig. 2): _shell not covered by membrane, white or
pale purple: orifice but slightly toothed: scutum generally with two
furrows_. Hab.--Chile, as far south as Concepcion; Peru; California.
_Var._ Coquimbensis (fig. 2 _a_): _with the basal cup partly filled
up with thin, irregular, calcareous layers, making a cancellated
mass_. Fossil, and recent.
_Hab._--Strait of Magellan, ten to twenty fathoms, attached to
shells; often entirely surrounding pebbles, forming globular masses;
associated with _Verruca lævigata_. Chile and Peru, (generally _var.
nitidus_), often attached to _Balanus psittacus_. California. Very
common.
_Fossil_ in an ancient tertiary formation (middle bed) at Coquimbo,
Chile. In a recent deposit (_var. nitidus_) at the height of 1000
feet at Valparaiso; with Human remains at San Lorenzo, Callao, Peru.
I may premise that, having myself collected this species from the same
locality, the Strait of Magellan, where no allied species occurs,
attached to the same Mytilus and associated with the same Verruca, I
feel confident that it is the _B. lævis_ described by Bruguière; and
there can hardly be any doubt that it is the _B. discors_ of Ranzani.
With respect to the old tertiary specimens from Coquimbo, named _B.
Coquimbensis_ by Sowerby, they differ from the recent in no respect,
except in being considerably larger; and therefore I cannot consider
them specifically distinct. At first I was unwilling to believe that
the specimens with a single very broad longitudinal furrow, and those
with two rather broad, or with one narrow furrow, on their scuta,
could belong to the same species; but I soon found that all these
varieties occurred mingled together, and that they differed in no
other respect whatever. Generally, however, all the individuals in the
same cluster had the same variety of scutum,--thus adding one more to
the many instances amongst cirripedes of variations common to whole
groups of specimens. Still more unwilling was I to believe that _var.
nitidus_ and the common variety could belong to the same species. Their
general aspect is totally unlike: _var. nitidus_ has a smooth, clean,
naked shell, either white or pale purple, somewhat globulo-conical,
often with a nearly entire orifice; whereas the other common variety
generally has a more steeply conical shell, with a toothed orifice,
and is covered by a dirty brownish membrane. Moreover, though I have
seen hundreds of specimens from Tierra del Fuego, I have not seen one
specimen of _var. nitidus_, or even of an approach to it in appearance;
and, on the other hand, _var. nitidus_ is the common form in Chile and
Peru; though I have seen one or two specimens of the membrane-covered
variety from Valparaiso. Such facts strongly induced me to believe that
these forms were specifically distinct; but upon careful examination
I could find no other or more important differences than those just
specified. Some specimens from northern Chile are in an intermediate
condition; and from Concepcion, in the south of Chile, where the
climate approaches in character to that of the more southern parts of
the Continent, there are many specimens, in so intermediate a condition
that I know not whether or no to rank them under _var. nitidus_. Thus
I became convinced that these forms are only varieties. At Concepcion,
some few specimens are pale purple, and yet are wholly invested by
thick brown membrane, thus uniting the two extreme varieties. From
California I have seen both varieties, but I do not know which is
most common there. With respect to the great difference in aspect
between the specimens from northern Chile and Tierra del Fuego, we
shall hereafter see a strictly analogous case in _Balanus flosculus_.
Finally, I may add that _B. lævis_ seems to represent in the southern
hemisphere and on the west coast of North America, the _B. perforatus_
of Europe and Western Africa.
_General Appearance._--Shell conical, sometimes slightly globular;
surface smooth (that is, not folded), either naked, and in that case
white or pale purple, or covered by dirty yellowish-brown membrane.
Orifice small, more or less toothed, rarely exceeding one third of
the basal diameter. Radii very narrow, often not developed, the six
sutures forming in all cases deep and narrow clefts. The largest
recent, but much depressed, specimen which I have seen (from the
Strait of Magellan) was three fourths of an inch in basal diameter;
specimens growing congregated are often much elongated. I have seen
one with the basal cup between two and three times as deep as the
height of the compartments. Of the ancient tertiary specimens, the
largest had a diameter of three fourths of an inch, and a total
length of actually two inches (fig. 2 _a_); another of these fossils
had a basal cup in depth equalling four fifths of the entire length
of the shell and basis.
The _scutum_ has either one very broad and deep longitudinal furrow
(2 _b_), or two moderately broad and deep (2 _e_), or two narrow and
deep, or less frequently one narrow and inconspicuous longitudinal
furrow (2 _f_); rarely there is not one furrow; sometimes there are
none towards the apex, whilst furrows have been formed in the lower
part of the valve. In young specimens the furrows extend down to
the actual basal margin, but in old specimens they often fall short
of this, and, as a consequence, the furrows become crossed by one,
two, or three calcareous ridges, which ridges at successive periods
formed the basal margin of the valve. The external surface is covered
by yellow membrane; and fragments of several successive opercular
membranes are often attached to the zones of growth.
Internally the articular ridge is not very prominent, but is
remarkable (2 _c_, 2 _d_) from its lower point being produced into a
long, sharp, sub-cylindrical, free style (like the hinge of a common
gate), which is generally broken off in disarticulating the valve
from the tergum. The adductor ridge is either sharp and prominent
or blunt: it extends up the middle of the valve nearly to the apex,
and downwards it trends a little towards the occludent margin. The
pit for the lateral depressor muscle is minute but deep: the basal
margin is sometimes hollowed out under this pit. Sometimes there is
a distinct, but blunt ridge, caused by one of the furrows outside,
parallel to the adductor ridge, and placed between it and the little
pit for the lateral depressor; in this case, the basal margin, as
viewed internally, is rendered sinuous (2 _d_), as is best exhibited
in the great fossil specimens from Coquimbo.
_Tergum_ (2 _g_).--Spur of moderate length and breadth, with its
lower end obliquely truncated and rounded. The longitudinal furrow
has its edges somewhat folded in. The basal margin on the carinal
side of the spur is sometimes a little hollowed out. The crests for
the depressor muscles are well developed; but the corner of the valve
supporting them is extremely thin, and is often imperfectly calcified.
_Compartments._--The parietal tubes are not crossed by transverse
septa, but in their upper parts are filled up solidly. The radii are
always very narrow, with their summits oblique, though to a variable
degree: their sutural edges have fine and closely approximate septa,
with minute denticuli: the sutural edges are received in a furrow, on
the opposed compartment, of unusual depth; hence the lines of suture
run, in the lower part of the shell, almost exactly in the middle
between each two compartments. The alæ are added to above the level
of the opercular membrane.
The _Basis_ is often thick, with an underlying layer, largely
cancellated or honeycombed. When many specimens grow crowded
together, the basis is generally deeply cup-formed, or even
sub-cylindrical; and equals as much as four fifths of the length of
the entire shell. In such cases, in some few recent specimens, and
in all the large or even quarter-grown old tertiary specimens, but
not in the quite young fossil specimens, a structure is presented,
which I have not seen in any other Cirripede, namely, the basis (Pl.
4, fig. 2 _a_) is filled up for one third, or even for more than
half its depth, by successive, separate, calcareous, transverse
layers or septa. It would appear as if the basal cup had grown too
large for the animal's body, and so required filling up. The layers
are thin and fragile; a single layer never stretches across the
whole shell; each is irregularly mammillated or blistered, with the
convex surfaces generally directed upwards; the layers are furnished
on their under sides with little pillars and short ridges, resting
on the layers beneath; it rarely happens that the supports of one
layer lie directly over those of another, though this is sometimes
the case. In a vertical section, the mass formed by these irregular
layers has a coarsely cancellated structure. This structure, although
confined to this one Cirripede, is not so anomalous as might at first
be thought, for in most species of the genus, each time that the
circumference of the basis is added to, an excessively thin calcified
film is thrown down over its whole inner surface; and in any of these
species, if the films had been formed thicker and had rested only
on certain points, instead of over the whole underlying layer, the
cancellated structure above described would have been produced.
_Mouth_: the labrum is either destitute of teeth, or has two or three
very minute teeth. The palpi have a tuft of very long spines at their
ends. The third tooth of the mandibles is thicker and larger than
the two upper ones. The maxillæ have either a nearly straight edge,
or the inferior corner is obliquely truncated, and projects much
beyond the rest of the edge. In the _Cirri_, none of the segments are
very protuberant: in the first pair, one ramus is nearly twice as
long as the other: in the posterior pairs, the segments are not much
elongated, but each supports seven pairs of spines.
_Var. nitidus_: with respect to this variety I have little to add
to my preliminary remarks on its peculiar appearance, owing to its
smooth, naked condition, and pure white or pale purple colour. This
colour, when examined through a lens, is seen to consist of very
fine longitudinal stripes; and is produced by the calcareous matter
within the longitudinal parietal pores being thus coloured. Generally
the scuta have two longitudinal furrows; but I have seen a scutum
of one perfectly characterised specimen with only a single broad
furrow, like that which frequently occurs in the membrane-covered
variety. _Var. Coquimbensis_, as before stated, differs only in its
greater size: the scutum, in the one specimen examined, had two
broad longitudinal furrows; neither it, nor the tergum differed from
certain varieties now found on the coast of Chile.
17. BALANUS PERFORATUS. Pl. 5, fig. 1 _a_-1 _d_; Pl. 4, fig. 3 _a_-3
_c_.
BALANUS PERFORATUS. _Bruguière._ Encyclop. Meth., 1789, Tab. 164,
fig. 12 _infra_.
LEPAS ANGUSTA. _Gmelin._ Syst. Naturæ, 1789.
---- ORE ANGUSTIORE. _Chemnitz._ Vol. viii, Tab. 98, fig. 835.
BALANUS CORNUBIENSIS CONICO ORE MINORE. _Ellis._ Phil. Trans. vol.
50, 1758, Tab. 34, fig. 16.
LEPAS BALANUS ET FISTULOSUS. _Poli._ Test. Siciliæ (1795), Tab. 4,
fig. 5, Tab. 6, fig. 1.
BALANUS COMMUNIS. _Pulteney._ Dorset Catalogue, 1799.
---- ---- _Montagu._ Test. Brit., 1803.
LEPAS ANGUSTATA. _Wood._ General Conchology, 1815, Pl. 6, fig. 5.
BALANUS CRANCHII. _Leach_ (!). (_B. Blainvillii_ in Tab.) Encyclop.
Brit. Suppl., vol. iii, 1824.
---- ---- _Brown._ Illust. Conch., 1827, Pl. 7, fig. 9, 10, and 2d
Edit., Pl. 53, fig. 9-12.
---- PERFORATUS. _Chenu._ Illust. Conch., Tab. 3, fig. 9, Tab. 6,
fig. 15.[92]
[92] I have very little doubt regarding any of these references:
I have no means of ascertaining the priority, within the same
year, of Gmelin and Bruguière, but have given it to the latter,
as _perforatus_ is much the best known specific name. English
conchologists seem generally to suppose that the _B. communis_ of
Pulteney and Montagu is the _B. porcatus_ of this work; but I have
not the smallest doubt that I have given it rightly as a synonym
of the present species; the indistinctness of the compartments,
the multitude of fine ridges, the smallness of the orifice, the
longitudinal furrow on the terga, the colour, size, and habitat,
all given by Pulteney or Montagu, will agree with no other British
species. The _Lepas balanus_ of Poli, which is certainly a synonym
of our present species, has been erroneously considered by several
authors to be the same with the _L. balanoides_ of Poli, which
latter undoubtedly is the _B. amphitrite_ of this work.
_Shell pale purple, or white, or dirty ash-colour; smooth, or, from
being corroded, finely ribbed longitudinally; sheath purple; orifice
generally small; radii generally narrow or absent. Scutum, internally,
with a short minute ridge, parallel and close under the prominent
adductor ridge. Tergum with the apex somewhat produced._
_Var._ angustus (_Gmelin_) Pl. 5, fig. 1 _a_: _pale dull purple
or white; orifice small or of moderate size; radii very narrow or
moderately wide, white or pale purple, with oblique summits_.
_Var._ Cranchii (_Leach_) Pl. 5, fig. 1 _b_: _corroded, covered with
fine longitudinal ridges owing to the exposed, filled-up, parietal
tubes; dark dirty ash-colour, with a tinge of purple: radii not
developed, or very narrow with oblique summits; orifice small_.
_Var._ fistulosus (_Poli_) Pl. 5, fig. 1 _d_: _shell cylindrical,
white or dull purple; orifice of moderate size or small; basis deeply
cup-formed_.
_Var._ mirabilis, Pl. 5, fig. 1 _c_: _bright purple; radii white,
very broad, with their summits parallel to the basis; orifice entire,
large_.
_Hab._--Southern shores of England; South Wales; Mediterranean;
Western Africa, southward to Loanda, in 9° S.; West Indies (?).
Generally adhering to rocks at a low tidal level; in one case
attached to the floating _Lepas Hillii_, Mus. Jeffreys.
This is a well-marked species, and in its essential characters does
not vary much; but owing to the shell being almost as often white as
purple,--to its being remarkably subject to disintegration,--to its
often becoming cylindrical,--to the radii being either not at all, or
slightly, or moderately, or largely developed, and consequently to the
orifice of the shell varying in size, the general external appearance
of the different varieties is singularly diversified; but when a series
of specimens is examined, it is easy to see how one form passes into
another.
_General Appearance._--Shell conical, with the orifice oval,
unusually small, being generally only from one third to half of the
basal diameter; sometimes moderately large; in one single instance as
wide as the basis. Radii, often represented by mere lineal fissures,
or they are narrow, or sometimes moderately wide. Colour pale, dull
purple, sometimes lilac, often passing into a dead pure white: the
same individual will occasionally have one part of its shell white,
and another purple: the purple tint almost invariably is nearly
uniform, or not in stripes. The radii are generally white, when
the whole shell is purple, but sometimes they are pale purple: the
sheath is apparently always coloured of a fine claret-purple, with
the triangular portion of the alæ, added during diametric growth,
generally white, but sometimes purple. The surface is quite smooth,
but very often, especially on the shores of England, whole groups of
specimens (excepting the very young ones,) have had the outer lamina
of the parietes entirely corroded and removed; in this case the shell
assumes a dirty, more or less dark, ash-colour, feebly tinted with
purple, and the whole surface, owing to the exposure of the solidly
filled-up parietal tubes, becomes finely striated, or covered with
very narrow, longitudinal ridges. When specimens are crowded together
they often become cylindrical, and much elongated, owing to the
basis becoming deeply cup-formed: I have seen specimens, half an
inch in diameter in the widest part, one inch and a half in height,
the walls forming only a third of this. The largest specimen which I
have seen (from the southern shores of England) had a basal diameter
of 1.2 of an inch; some very steeply conical specimens were .9 of an
inch in height, and .8 in basal diameter.
_Scuta_, externally, slightly convex; growth-ridges approximate,
moderately prominent. Internally (Pl. 4, fig. 3 _a_) the articular
ridge is moderately developed, with the lower end produced downwards
into a freely depending, flattened style, somewhat variable in
size, but not so long as in _B. lævis_, and easily broken in
disarticulating the valves. The adductor ridge is very prominent,
running from almost the apex of the valve, close to the articular
ridge, to near the basal margin. The basi-tergal portion of the
valve is converted by the adductor ridge into a rather deep cavity,
within which there is a short, sharp, and minute ridge, close and
parallel to the adductor ridge, and bounding the impression left by
the lateral depressor muscle: this insignificant ridge was present
in every specimen; it occurs only in very few other species, as in
_B. nubilus_ and _cariosus_. The thickness of the valve sometimes
varies a little, and when thick the adductor ridge does not appear
quite so prominent. _Tergum_, with the apex moderately beaked and
produced; beak triangular in section, coloured dark purple, as is
the upper internal surface of the valve; the longitudinal furrow is
deep, and has its edges folded in, and even quite closed. The spur
is moderately long and narrow; but its width varies a little (Pl. 4,
fig. 3 _b_, 3 _c_), and consequently it stands at either rather above
or at twice its own breadth from the basi-scutal angle: its lower
end is either bluntly pointed or square, and generally is feebly
toothed on the under-side. The basal margin of the valve generally
slopes a little, on both sides, towards the spur. Internally, the
scutal margin is but slightly inflected: the articular ridge is but
slightly prominent, and but little curved; in the upper part of the
valve there are generally several very minute ridges, parallel to the
articular ridge, on the side towards the scutum. The internal surface
of the spur itself is sometimes concave. The crests for the carinal
depressor muscle are barely developed. It may here be mentioned that
on the opercular membrane many long spines stand rudely arranged in
rows.
_Parietes_: the parietal tubes have not transverse septa; but
are solidly filled up in their upper parts by dark-purple layers
of shell. The _radii_, as already stated, are either not at all
developed, or are extremely or only moderately narrow, with their
summits more or less oblique: in Mr. Cuming's collection, however,
there is an unique specimen, _var. mirabilis_ (Pl. 5, fig. 1
_c_) with the aperture of the shell as wide as the basis, with
bright purple parietes, and white, very broad radii, having their
summits parallel to the basis. The septa of the radii are finely
denticulated, and the interspaces are filled up solidly. The _alæ_
have very oblique summits, and their edges are finely crenated.
_Basis_, flat, or deeply cup-shaped; there is often an underlying,
coarsely-cancellated layer.
_Mouth_: labrum finely hairy, but without any teeth; mandibles, with
the 4th tooth small; the 5th confluent, with the sometimes smooth,
sometimes pectinated inferior angle. Maxillæ, rather broad, with a
slight notch under the upper pair of spines. _Cirri_, first pair,
with one ramus, having 29 segments, and above one third longer than
the shorter ramus, having 17 segments; these latter segments are
remarkable by the extent to which their upper front surfaces are
laterally produced into projections, twice as long as the breadth of
that portion of the segment which is articulated to the adjoining
segment. These projections have a double row of serrated spines on
their upper edge, and a beautiful radiating bundle at the end; the
projections decrease in length, both in the upper and lower segments.
The second cirrus (Pl. 29, fig. 4) has the segments (13 in number, in
the same individual with the segments above enumerated) of both rami
produced in the same singular manner as in the first pair. The third
pair have only inverted conical segments, coloured darker purple than
the other cirri. The sixth pair had in the same individual 31 or 32
segments, and therefore one or two more than in the longer ramus of
the first pair.[93] The segments in the posterior cirri have their
anterior faces shield-shaped, and bear 6 or 7 pairs of spines, with
some minute intermediate spines. There is the usual point at the
dorsal basis of the penis.
[93] Under the Genus (p. 190) I have given the numbers of the
segments in the cirri of this species at successive ages.
_Range._--This species is common on the southern shores of England
and in the Channel Islands: the largest specimens which I have seen
came from these quarters. The most northern point whence I have
seen specimens, is Tenby, in South Wales. This species is common
throughout the Mediterranean; I have seen specimens from Malaga,
Sicily, Algiers, and Smyrna; thence it ranges down the western
coast of Africa, as far south as the Gambia and Loanda, in 9° south
latitude. I believe British specimens are more often corroded than
those from further south. Amongst some old, ill-kept specimens in a
box in the British Museum, marked "Kingston, Jamaica," there were
some of this species: also I received some specimens, marked "S.
America," from Mr. G. B. Sowerby: again, Ellis, in Phil. Trans., vol.
50, part 11, gives a figure (Tab. 34, fig. 15) of some specimens from
the West Indies, which I believe to be _B. perforatus_: hence, it is
in some degree probable that this species, like _B. tintinnabulum_,
and _amphitrite_, and _improvisus_, may be found on both sides of the
equatorial Atlantic. _Balanus perforatus_ is attached, together with
_B. tulipiformis_, _trigonus_, _amphitrite_, _Chthamalus stellatus_,
and _Pollicipes cornucopia_, usually to rocks, near the lower limit
of the tidal level; but I believe, from specimens kindly sent me
by Mr. Mac Andrew, that it is frequently obtained by dredging;
one specimen was even marked 30 fathoms. According to Poli, it is
sometimes attached to the bottoms of vessels; and I have seen a
specimen adhering to the floating _Lepas Hillii_.
_Affinities._--This is a distinct species, closely allied to no other
species, but comes nearest to _B. lævis_, which is its representative
in Southern America, and on the whole west coast of that continent.
It is allied to that species, and differs from most other species,
in the general form of the shell, its small orifice, narrow radii,
and often deeply cup-formed basis. It agrees to a certain extent in
the colouring, though the purple here is much more prevalent, and
is not confined to the shelly matter filling up the parietal tubes.
It agrees with that species in the general structure of the scutum;
but the two or three deep, longitudinal furrows are here absent; and
the minute ridge, parallel to and almost under the adductor ridge,
is a peculiarity confined to this and very few species in the genus.
The terga differ from those of _B. lævis_, chiefly in the spur
being narrower, and in the apex being beaked. Lastly, the highly
protuberant segments of the one ramus in the first cirrus, and of
both rami in the second pair, are here remarkable. With regard to the
varieties, I have nothing to add to their short diagnostic characters
above given.