Chapter XIV: Introduction (10)

_Terga_ (2 _b_, 2 _d_): the longitudinal furrow is deep, with the
sides folded in; the spur is placed at about its own width from
the basi-scutal angle; it is moderately long, with its lower end
obliquely rounded off; but the length, breadth, and precise outline
of the lower end varies a little. The basal margin on the opposite
sides of the spur, forms a nearly straight line, but with the
portion on the carinal side very slightly hollowed out. Crests for
the depressor muscle are well developed.

_Compartments._--The radii and alæ always have their summits oblique:
the sutural edges of the radii are deeply penetrated by pores between
the strongly denticulated septa: the sutural edges of the alæ are
quite smooth: the tubes in the parietes are crossed in the upper
part of the shell by septa. _Basis_ tubular, with an underlying
cancellated mass.

_Mouth._--Labrum with the teeth either absent or very small:
mandibles with the fourth and fifth teeth rudimentary: maxillæ with
a small notch under the two upper spines; near the lower angle,
two spines, one beneath the other, are larger even than the upper
pair; beneath the lower pair, there is a tuft of fine spines.
_Cirri_, segments protuberant in one ramus of the first cirrus and
in both rami of the second cirrus; posterior cirri with the segments
short and broad, each bearing three pairs of spines, with a small
intermediate tuft.

_Affinities._--This species in all essential respects comes very near
to the three last varieties of _B. tintinnabulum_, which have the
orifices of their shells toothed. The smoothness of the scutum, with
its persistent epidermis,--its peculiar shape,--its small and not
reflexed articular ridge,--together with the crests on the tergum for
the depressor muscles, are sufficient diagnostic characters. Even in
general habit and tint of colour, this species has a different aspect
from _B. tintinnabulum_. In some respects _B. tulipiformis_ leads
into the species included in the third section of the genus.

3. BALANUS PSITTACUS. Pl. 2, fig. 3 _a_-3 _d_.

LEPAS PSITTACUS. _Molina._ Hist. Nat. Chile (1788), vol. i, p. 223.

BALANUS PICOS. _Lesson._ Zoolog. Voyage de la Coquille (1829).

---- TINTINNABULUM (var. c). _Ranzani._ Mem. di Storia Nat. tab. 3,
fig. 1-3 (1820).

---- CYLINDRACEUS. _Lamarck_, in _Chenu_. Illust. Conch. Tab. 4,
fig. 17, Tab. 5, fig. 7, sed non var. (_c._) in Lamarck,
Animaux sans Vert., (1818).

---- PSITTACUS. _King_ and _Broderip_. Zoolog. Journal, vol. v
(1832-1834), p. 332.

_Shell, pale dirty pink; orifice hexagonal. Scutum with the articular ridge very small, confluent with the very prominent adductor ridge, forming a tubular cavity, which extends up to the apex of the valve. Tergum with the apex produced, needle-like, purple: spur placed at less than its own width from the basi-scutal angle._

_Hab._--Peru, Chile, Chiloe, Patagonia. Fossil in an ancient tertiary
deposit, Coquimbo; and in a superficial, recent bed at S. Josef, in
Patagonia.

_General appearance._--Shell either almost cylindrical or steeply
conical, generally flesh-coloured, sometimes pale pink; surface
either smooth (when not disintegrated) or sometimes with the parietes
distinctly and rather strongly ribbed, with the ribs distant from
each other: I have seen six or seven ribs on the rostrum alone. The
orifice in the most perfect specimens is nearly equilateral and
hexagonal. The radii generally are very broad, but occasionally
quite narrow, and even linear. The basis is generally deeply and
irregularly cup-formed.

_Size._--This is the largest species in the family: I have seen a
specimen six inches in length and three and a half in diameter; and
another specimen no less than nine in length, though only two and a
half inches in diameter.

_Scuta._--In full-sized specimens the surface is finely striated
longitudinally, caused by the lines of growth being minutely sinuous;
but in young specimens, until they attain a basal diameter of above
half an inch, the surface is smooth. The valve is transversely
arched, a line of flexure running from the apex to the basal margin,
at about one third of the width of the valve from the tergal margin.
The basal margin is curved nearly continuously, and extends nearly
half-way up the valve; hence the basi-tergal corner is largely
rounded off. The articular ridge is but little prominent, and is not
reflexed: the articular furrow is very narrow. The adductor ridge
consists of a sharp, much-projecting plate, running down close to the
basal margin, and is confluent with the lower part of the articular
ridge. This plate and the inflected tergal margin of the valve,
together form a large and deep cavity, which extends up almost to the
apex of the valve. The depressor muscle is attached in the middle, at
the lower, open end of this cavity.

_Terga._--These are strongly beaked, the beak being from one third
to one fourth of the total length of the valve, including the spur:
the beak is very sharp, somewhat flattened, and bowed; when young,
and when well preserved, it is coloured purple: it is penetrated
by a fine tubular cavity, occupied by a thread of corium, which
extends about half-way up it. The whole valve is narrow, being about
thrice as long as wide. The spur is also long and narrow; it is
seated at less than its own width from the basi-scutal angle. The
scutal margin is not much inflected. The longitudinal furrow has its
sides, in full-grown specimens, closely folded together. The basal
margin slopes down on both sides to the spur. There are no crests,
or only traces of them, for the attachment of the depressor muscle.
Internally, the spur is prolonged, as a prominent ridge, upwards to
the beak, and serves as an articular ridge. In the middle, in the
upper part (Pl. 2, fig. 3 _d_), between this articular ridge and the
carinal margin, there is a second narrow ridge, which extends from
the lower part of the beak half-way down the valve, and then dies
out. The space between these two ridges, and the ridges themselves,
are coloured purple, and consist of harder shell than the rest of
the valve; hence, when the outer surface and the adjoining scutal and
carinal margins disintegrate, this part remains, and so forms the
beaked, purple apex.

_Compartments._--The parietal tubes are unusually large in proportion
to the size of the shell, and run up to the summit without any
transverse septa: the longitudinal septa are strongly denticulated.
The radii are penetrated by large tubes; their septa are very
strongly denticulated, and the denticuli themselves often subdivide
and branch out at their extremities. The sutural edges of the alæ
are smooth, or with a high power can just be seen to be crenated.
The radii are generally very highly developed, so that their summits
are even wider than the bases of the parietes; but, on the other
hand, in some few large specimens, the radii are either very narrow
or absolutely linear. In these latter cases, the diametric growth
has nearly or altogether ceased, whilst the walls of the shell have
continued to be added to at their bases, their summits at the same
time suffering disintegration; and thus the orifice has increased in
size.

_Basis_ generally, and occasionally very deeply, cup-formed. An
unusually thick cancellated layer in most cases forms the under side
of the basis.

_Mouth._--Labrum apparently without teeth, or with very minute ones:
mandibles with three teeth, of which the third is thicker than the
first or upper one: the fourth and fifth teeth are confluent with the
inferior angle. The maxillæ have a small notch under the upper pair
of spines; inferior part projecting and supporting two spines, placed
one below the other, and equalling in size the upper pair. _Cirri_:
the rami of the first cirrus are unequal by four or five segments;
shorter ramus and both rami of the second cirrus with the segments
extremely protuberant: posterior cirri not much elongated, with the
segments rather broad, supporting six pairs of spines.

_General Remarks._--This, which is much the largest known species
of the genus, ranges from Peru (Arica being the most northern spot,
whence I have seen specimens), along the coast of Chile, where it
is very abundant at a few fathoms' depth, at least as far south as
Southern Chiloe; it is said by Captain King to attain the largest
size at Conception. On the coast of Eastern Patagonia, I dredged
up this species from nineteen fathoms, in lat. 49°. In lat. 42°
(S. Josef), on the same eastern coast, I found fossil specimens
in beds of sand upraised between eighty and one hundred feet. In
the tertiary formation at Coquimbo, in Chile, it occurs in the
middle bed, associated with the recent _B. lævis_, and with various
mollusca, all of which are apparently extinct, indicating that the
formation is of considerable antiquity. In the living state, on
the coast of Chile, it is often associated with _B. lævis_. As it
frequently adheres to large specimens of the Concholepas, it must
sometimes be an inhabitant of shallow water. I have seen one specimen
attached to _Mytilus Magellanicus_. Mr. Cuming believes that about
six fathoms is the usual depth at which it lives. Numerous specimens
are often congregated together into great masses. Mr. Stutchbury has
some interesting specimens which he procured from a ship that had
first sailed to Ichaboe, on the coast of Africa, and afterwards
to Patagonia; consequently numerous specimens of _B. psittacus_
had become attached on _B. tintinnabulum_, and subsequently during
the voyage home, some few of the latter again had adhered on _B.
psittacus_: the contrast in the paler colour and hexagonal orifice
of this species, with the darker tints and more trigonal orifice of
_B. tintinnabulum_ was striking. At Coquimbo, in Chile, I procured
a specimen of _B. psittacus_, attached to a chain cable which had
been in the water only six months; this specimen measured 1.3 of an
inch in basal diameter, and .8 in height: this shows a rapid rate of
growth. Lastly, I may mention that it is asserted by Molina, and I am
assured by Mr. Cuming that the statement is perfectly correct, that
this Balanus, when cooked, is universally esteemed as a delicious
article of food.

4. BALANUS CAPENSIS. Pl. 2, fig. 4 _a_, 4 _b_.

BALANUS CAPENSIS ORE OBLIQUO. _Ellis._ Phil. Transact., vol. 50
(1758), Tab. 34, fig. 14.

_Shell shaded, and often longitudinally striped with bright pink. Scutum as in B. psittacus. Tergum with the apex produced and needle-like, white: spur placed at its own width from the basi-scutal angle._

_Hab._--Cape of Good Hope. Attached to stems of Fuci, Algoa Bay. Mus.
Brit. and Bowerbank. Attached to a Patella, Mus. Darwin, Mus. Cuming,
and Stutchbury. Attached to floating kelp, Lagulhas Bank, Mus. James
Ross, associated with _B. tintinnabulum_ and _spongicola_.

This species comes extremely close to the South American _B.
psittacus_, and I should hardly have attached a specific name to
it, had I not examined many specimens, young and old, of the true
_B. psittacus_, from Peru, Chile, and Eastern Patagonia, and found
them all identical in the few, apparently trifling points, in
which that species differs from _B. capensis_. The animal's body
and the shell agree in every respect, excepting that the shell is
decidedly pinker, being often most distinctly and prettily striped
longitudinally with pale and bright pink. In some of the specimens
the basis is cup-formed: in some, the broad radii are pale pink,
in others they are quite white, and in this latter case a singular
aspect is given to the pinkish varieties. In very large specimens
(and I have seen one fully two inches in basal diameter) the pink
colour is extremely feeble, and the whole shell has a very rugged,
disintegrated, coarse, and sometimes dirty appearance: in most
of these large specimens the walls are more massive than in _B.
psittacus_, and the orifice of the shell rather smaller; in some,
however, the walls certainly are of unusual thinness.

The _Scuta_ differ from those of _B. psittacus_ only in the
basi-tergal corner not being so much rounded off, and consequently
in the articular ridge, which is rather more reflexed, descending in
proportion lower down the valve: the cavity at the basi-tergal corner
is in proportion broader. The valves in the two species differ, also,
but only in young specimens, in the occludent half being tinted,
both externally and internally, purple, whereas in _B. psittacus_
the whole valve, at all ages, is white. In the _terga_ the spur is
removed fully its own width from the basi-scutal angle, whereas it
is not half this distance in _B. psittacus_. The scutal margin is
here much more inflected. In _B. psittacus_ there is a remarkable
patch of purple on the inside of the valve, between the articular
ridge and a second special ridge; of this purple patch there is here
no trace, consequently the beak or apex is white. The beak, also, is
less prominent. The special ridge, just alluded to, here runs much
nearer to the articular ridge, and is less prominent: indeed, in old
specimens, it is often almost obliterated. Finally, the whole valve,
in proportion to the Scutum, is rather broader.

I have seen a young specimen, about a quarter of an inch in basal
diameter, with the orifice of the shell toothed owing to the
obliquity of the summits of the radii; and this gave the shell a very
peculiar aspect. The largest well-coloured specimen which I have seen
is 1.2 of an inch in basal diameter; but in Mr. Cuming's collection
there are two rugged, disintegrated specimens, two inches in basal
diameter, and two and a half in height. Some specimens, 1.3 in basal
diameter, in Mr. Stutchbury's collection, are remarkable from the
radii having been obliterated--the shell being merely divided by six
sutures, as we have seen is likewise sometimes the case with large
specimens of _B. psittacus_.

This species is evidently a South African representative of the South
American _B. psittacus_.

5. BALANUS NIGRESCENS. Pl. 2, fig. 5 _a_, 5 _b_.

BALANUS NIGRESCENS. _Lamarck_, (1818) in _Chenu_. Illust. Conch.,
Tab. 4, fig. 16.

---- GIGAS. _Ranzani._ Memoire di Storia Nat., 1820, Tab. 3, fig. 5,
6, 7.

---- ---- _De Blainville._ Dict. des Sc. Nat., Tab. 116, fig. 2, 2
_a_.

_Shell cinereous, tinted with pale or blackish blue, or wholly white. Scutum with the articular ridge terminating downwards in a small, sharp, free point: adductor ridge prominent. Tergum with the apex produced and needle-like._

_Hab._--Swan River, West Australia, Mus. Brit., attached to
sandstone. Attached to sandstone and to each other in a group, Mus.
Cuming. Twofold Bay, S. E. Australia, attached to tidal rocks and
Patellæ, Mus. Darwin.

There can be no doubt that this species is the _B. nigrescens_ in Chenu, who had access to Lamarck's original specimens; and there can be equally little doubt that it is the _B. gigas_ of Ranzani, collected, during Baudin's expedition, at King George's Sound: it is essentially allied to _B. psittacus_, but in external appearance strikingly resembles some of the varieties of _B. tintinnabulum_.

_General Appearance._--Shape tubulo-conical: walls smooth, sometimes
longitudinally ribbed: colour ashy-gray tinged with blue, but many
specimens are dark purplish-blue, owing to the disintegration of the
outer lamina, and consequent exposure of the almost solidly filled
up, dark blueish parietal tubes; on the other hand, some specimens
are quite white. Ranzani describes the colour as earthy-violet, which
is very characteristic of some of the specimens. The orifice is apt
to be rather small, compared to the size of the specimens, and tends
to be hexagonal. The radii are often rather narrow. The opercular
valves are tinted pale blue. The basal diameter of the largest
specimen is two inches, and its height two and a quarter.

The _Scuta_ have their basi-tergal corner much rounded off, as in
_B. psittacus_, so that the tergal margin does not extend more than
half down the valve. The surface is somewhat prominent, along a line
running from the apex to the point of chief curvature in the basal
margin. The surface is not striated. Internally, the articular ridge
is little prominent, and not reflexed; the lower end depends as a
free, sharp style or point. The adductor ridge is moderately sharp,
and stands some little way distant from the articular ridge: it is
produced downwards, and forms a moderately deep and large cavity for
the depressor muscle; but this cavity is not closed, and does not
extend up, as in the two last species, to the apex of the valve.

_Terga_, narrow, with a sharp, prominent, needle-like beak. Spur,
long, narrow, placed at less than its own width from the basi-scutal
angle: the basal margin on both sides slopes down to the spur: the
scutal margin is not inflected. Internally, the articular ridge is
very feebly developed, but extends down close to the basi-scutal
angle. On the under surface in the upper part of the valve, there is
a short, very slight ridge, extending on the carinal side, near and
parallel to the articular ridge; this slight ridge plays an important
part, as in the two foregoing species, in the formation of the beak
or apex. Crests for the depressor muscle are hardly distinguishable.

The _Walls_ appear to vary in some degree in strength and thickness;
as is likewise the case with the opercular valves. In some of the
thinner specimens, the parietal tubes are large, and the longitudinal
septa are furnished with small, sharp denticula. The tubes are often
thickly lined or almost filled up solidly with blue shell; they are
not crossed by transverse septa.

The _Radii_ vary in width; externally they are often finely ribbed
transversely, at other times they are smooth; their septa are fine
and thin, with their delicate denticuli not extending to the outer
lamina: they are very porose. The _alæ_ have their summits parallel
to the basis; their sutural edges are most finely crenated. The
sheath is blueish, excepting the wedge-like portions of the alæ which
have been added during the diametric growth, and these are white.

_Mouth_: labrum without teeth: mandibles with five sharp teeth:
maxillæ with the edge straight. _Cirri_, first pair with the rami
very slightly unequal; segments of the shorter ramus and of both rami
of the second pair protuberant: posterior cirri with the segments
shield-shaped in front, bearing four pairs of spines, of which the
upper pair is much longer than the lower pairs; each pair has a small
intermediate tuft of minute spines.

6. BALANUS DECORUS. Pl. 2, fig. 6 _a_, 6 _b_.

_Parietes pale pink; radii rather darker. Scutum with a small articular ridge. Tergum with the longitudinal furrow very shallow and open; basal margin on both sides sloping towards the spur._

_Hab._--New Zealand. Mus. Brit., and Flower: attached to shells.

_General Appearance._--Shell conical or tubular, with a large
rhomboidal orifice; very pale pink, but tinted yellowish from the
persistent epidermis, and sometimes faintly striped longitudinally;
radii and sheath of rather a darker pink; scuta in themselves white,
though lined by purple corium; the carinal half of the tergum pink.
Walls extremely smooth. Largest specimen above one inch in basal
diameter.

_Scuta_, with the finest striæ radiating from the apex; growth-ridges
moderately prominent; articular ridge small; there is a very slight
and blunt adductor ridge: the hollow for the lateral depressor muscle
is rather narrow and deep.

_Terga_, with the apex slightly prominent or beaked; the longitudinal
furrow is of very little depth; on its scutal margin there is a
narrow, rounded, slightly prominent ridge, which, however, appears
more like a furrow than a ridge. Spur moderately long and blunt;
placed at half its own width from the basi-scutal angle; the
basal margin on both sides of the spur, slopes gently towards it.
Internally, the articular ridge is pretty well developed; the scutal
margin is not much inflected; the carinal portion of the under
surface of the valve is rough; the crests for the carinal depressor
muscle are entirely absent.

_Compartments._--Walls moderately strong; parietal tubes small, with
transverse septa in their upper ends; inner surface of the walls much
less strongly ribbed than is usual. _Radii_ broad, with their summits
parallel to the basis; their septa are strongly denticulated. _Alæ_
with their summits oblique; their sutural edges are barely crenated.
_Basis_, thin, flat, or cup-formed. _Body_ unknown.

_Affinities._--In general appearance this species comes near to _B.
psittacus_; but in all essential characters it comes much closer
to the following species, from which, however, it can easily be
distinguished by colour, and by the inner lamina of the parietes not
being cancellated.

7. BALANUS VINACEUS. Pl. 2, fig. 7 _a_-7 _d_.

_Shell purplish dark brown: inner lamina of the parietes cancellated. Scutum finely striated longitudinally. Tergum with the longitudinal furrow shallow and open; basal margin on both sides sloping towards the spur._

_Hab._--West Coast of South America. Mus. Cuming.

_General Appearance._--Shell conical, with a large, rhomboidal
orifice; walls rather thin, coloured, together with the radii and
operculum, dark purplish-brown; sheath nearly colourless. Walls
smooth, slightly irregular, very finely striated longitudinally.
Basal diameter of largest specimen .8 of an inch.

_Opercular Valves_, unusually smooth, that is without prominent
growth-ridges. _Scuta_, finely striated longitudinally, with the
sharp striæ closely approximate. The teeth on the occludent margin
are sharp, and stand some way apart from each other. Internally, the
whole surface is remarkably flat and smooth: the articular ridge is
of moderate breadth, and slightly reflexed: there is no adductor
ridge, and the oval depression for the lateral depressor muscle is
extremely slight. _Terga_, with the longitudinal furrow very slight;
the bottom of this furrow is feebly striated longitudinally, and
there is a trace of a fine, rounded ridge on the scutal margin, as in
_B. decorus_. The basal margin slopes on both sides towards the spur,
which is of moderate length and breadth, with its lower end truncated
and parallel to the carino-basal margin; the spur stands at about
once and a half its own width from the basi-scutal angle. Internally,
the valve is lined by very dark, purplish-brown corium; the articular
ridge is prominent; in the upper part of the valve, parallel to the
articular ridge, there are two or three feeble ridges; there are no
crests for the tergal depressores.

The _Parietes_, though moderately thick, yet are light and fragile;
the denticuli at the bases of the longitudinal septa are prominent,
and those on the adjoining septa are united together, making a
network (Pl. 2, fig. 7 _d_), but the interspaces between them are not
filled up by solid calcareous matter (as is the case with every other
species of the genus), but are only crossed at successive levels by
fine transverse calcareous septa; the internal lamina thus becoming
cancellated, and, though thick, fragile. Hence, in a transverse
section of the parietes, the ordinary parietal tubes or pores are
seen to be lined on their inner sides by five or six rows of very
minute pores. I have not seen any other instance of this structure.
The internal lamina is ribbed, as usual, on its inner surface, by
the projection of the longitudinal septa. The ordinary parietal
tubes are open, to nearly the summit of the shell. The _radii_ are
rather thin, and unusually fragile; their summits are parallel to
the basis: their septa, as seen on the sutural edges, are extremely
thin and denticulated on both their upper and lower surfaces, on the
side towards the internal lamina: towards the external lamina, the
septa are simple, and the small square pores thus formed, are open
or not filled up. The _alæ_ have their summits extremely oblique,
being added to very little during the diametric growth of the shell;
the narrow margin, however, which is thus added, is coloured red,
the rest of the sheath being nearly colourless: the sutural edges
of the alæ are smooth. The _basis_ has a thick, underlying, finely
cancellated layer of shell.

_Animal's body_ unknown.

A young specimen, .2 of an inch in basal diameter, differed from
the above in being of a much paler purplish-brown. This species is
distinct from all its congeners, in its peculiar colour, and likewise
in the structure of the inner lamina of the parietes. As already
stated, it comes nearer to _B. decorus_ than to any other species.

8. BALANUS AJAX. Pl. 3, fig. 1 _a_-1 _d_.

BALANUS TINTINNABULUM (_var._) _Chenu._ Illust. Conch., Tab. 2, fig.
8.

_Shell globulo-conical, often elongated in the rostro-carinal axis, pale pink, smooth, extremely massive: parietal pores, close to the basal margin, circular and very small. Scutum with the articular ridge broad and reflexed._

_Hab._--Philippine Archipelago, attached to _Millepora complanata_,
Mus. Cuming. Mus. Brit. and Stutchbury.

_General Appearance._--Shell globulo-convex, sometimes much elongated
in its rostro-carinal axis; smooth; walls excessively strong,
massive, and heavy. Orifice oval, rather small in proportion to the
size of shell, this being chiefly due to the infolding of the upper
part of the rostral compartment. Parietes pale pink, feebly tinted
with purple: radii either paler, or tinted of a bright chesnut-brown:
sheath rich purplish chesnut-brown. Basal diameter of the largest
specimen nearly 3-1/2 of an inch; height 2-3/4: another specimen had
a basal longitudinal diameter of 2.9 of an inch, and a transverse
diameter of only 1.6; this great difference in the two diameters
being caused by the prolongation of the basal portion of the rostrum
in the line of the branch of the Millepora, to which the shell had
adhered; the height of this same specimen was 1.5; and the diameter
of the orifice, both transversely and longitudinally, .75 of an inch.

_Scuta_, broad, feebly tinted with pink; exterior surface rough,
with sharp hood-formed projections, arranged in straight lines
radiating from the apex; an inflected portion of the valve along the
tergal margin is not roughened. Internally (Pl. 3, fig. 1 _d_), the
articular ridge is broad and reflexed. An adductor ridge can hardly
be said to exist, but a slight prominence borders the gentle hollow
in which the lateral depressor muscle is attached. The basal margin,
on its inner face, is slightly toothed. _Tergum_ white, with the
narrow part of the valve, on the scutal side of the spur, rough with
the little projecting hoods, like those on the scutum; the other and
larger half is smooth: spur rather long, narrow, placed at twice its
own width from the basi-scutal angle; on the carinal side, about half
of the basal margin slopes down towards the spur. The longitudinal
furrow is either quite or nearly closed. Internally, the spur is
produced upwards on the valve, as a prominence: the articular ridge
is not very prominent. There are no crests for the tergal depressor
muscle.

Altogether the opercular valves strikingly resemble those of _B.
tintinnabulum_, but all the characters above mentioned have not been
observed in any one variety of this species; perhaps _var. coccopoma_
comes nearest, both in the external appearance of the shell and in
the structure of the opercular valves, to _B. Ajax_.

The _Compartments_ are remarkably compact and solid; the parietal
tubes are cylindrical and quite minute even close to the basis; they
extend, however, nearly up to the top of the shell; the parietal
septa at the basis are thick, and with blunt denticuli; the thickness
of the walls in the upper part of the shell is excessive; in the
lower part, it is also unusually great, owing to the thickness of the
inner lamina, and hence the ribs, generally formed by the projection
of the longitudinal septa on the inner lamina, are here visible only
close to the basis. The _radii_ are rather wide; their summits are
parallel to the basis; the septa on their sutural edges are thin,
straight, and closely approximate, and most symmetrically furnished
with little denticuli of equal sizes on both sides: the interspaces
are nearly filled up solidly, but with some pores still left open.
In the upper part of the shell, the radii, like the walls, are of
extraordinary thickness: the septa are transverse and horizontal,
as seen externally by slight variations in the colour of the radii;
internally, as seen in a vertical section of the shell, the septa
dip inwards at an angle of above 45°. The _alæ_ are thin, and have
their summits oblique: their sutural edges are smooth. The pores in
the basis are crossed by numerous transverse septa, and there is an
underlying cancellated layer: the internal surface is very smooth.

_Animal's body_ unknown.

The strength of this Balanus is truly remarkable; and when, by
repeated blows, a specimen which I was examining at last yielded,
the radii broke sooner than separate at their sutures. In most of
its characters, this species approaches _B. tintinnabulum_, and I
believe has been included by Chenu as one of its varieties; but
it comes almost equally near to _B. stultus_, to which it is much
more closely allied in its habit of being attached to Milleporæ.
By a close and unbroken chain of affinities, _B. Ajax_, through _B.
stultus_, is connected with _B. calceolus_ and its allies in section
(B), which live attached to Gorgoniæ. Some of the specimens of _B.
Ajax_, are almost as much elongated in their rostro-carinal axis, as
are the species in section (B); and there is an affinity in the same
direction in the smallness of the pores in the radii of _B. Ajax_;
indeed, had the basis in this species been generally more boat-or
cup-formed, I should have placed it as the first species in section
(B), instead of, as at present, the last species in section (A). The
intermediateness of the characters of _B. Ajax_ has been one chief
cause why I have rejected the genus Conopea, which was instituted by
Say for the species living attached to Gorgoniæ.

_Section_ B.

_Parietes and basis sometimes permeated by pores, sometimes not: radii not permeated by pores: shell elongated in its rostro-carinal axis: basis boat-shaped: attached to Gorgoniæ and Milleporæ._

9. BALANUS STULTUS. Pl. 3, fig. 2 _a_-2 _d_.

_Parietes and base porose: shell white, or faintly tinged with purple. Scutum with the basal margin protuberant in the middle. Tergum with the longitudinal furrow closed in the upper part: spur not closely adjoining the basi-scutal angle._

_Hab._--Attached to Milleporæ, Singapore, Mus. Cuming. West
Indies,[89] Mus. Brit.--Mus. Stutchbury.

[89] This specimen in the British Museum was purchased at the sale
of the Rev. L. Guilding's collection, and therefore it is not
certain that this habitat is correct; but as it was sold in the
same lot with a Cirripede certainly West Indian, and as the main
collection was made in the West Indies, this habitat may, I think,
be trusted.

I have considerable doubts whether it would not have been more correct to have placed this species in the last section, instead of where it now stands; it certainly is more closely allied to _B. Ajax_, especially in its operculum, than to the following species; yet the fact of the radii not being permeated by pores does not permit of its admission into the last section; and both in habits and structure it undoubtedly comes very near to the following species. Those varieties which are not much elongated, and which have the basis nearly flat, would certainly, if considered by themselves alone, not have gained admission into our present section.

_General Appearance._--Shell conical, somewhat globular, more or less
elongated in the rostro-carinal axis, owing to the basal production
of the rostrum. Orifice, rather small, entire, oval, pointed at the
carinal end. Radii moderately broad, with their summits parallel to
the basis. Colour dirty white, often faintly tinged with purple;
sheath, pale purplish-blue. Surface extremely smooth; the parietes
are generally covered (as viewed through a lens) by a very thin,
yellowish epidermis, giving to the whole a glistening, granular
aspect: the radii are generally destitute of this epidermis, and are
therefore of a dead white. The basis is concave, and sometimes deeply
cup-formed; it is, however, not symmetrical; sometimes it is flat.
Basal diameter of largest specimen, including the basis itself, 1.5
of an inch in the longitudinal axis; transverse diameter, 1 inch; the
inequality in the length of the two diameters is rarely so great as
in this unusually large specimen.

_Scuta_, externally very convex, with the growth-ridges extremely
prominent; basal margin sinuous, the middle portion being prominent;
this is best seen in young specimens (Pl. 3, fig. 2 _d_). Internally,
the articular ridge is broad and reflexed. The adductor ridge in the
upper part is almost confluent with the articular ridge; it runs down
to the most prominent point of the basal margin; in young specimens
it is sharp and prominent; in old specimens it is very blunt and
little prominent. There is a rather deep hollow for the lateral
depressor muscle. In young specimens there is a small, depending,
blunt tooth at the basi-tergal angle, which helps to make the basal
margin more deeply sinuous.

_Terga_, with the longitudinal furrow closed, except on the spur
itself, where it is open. The spur is moderately long and broad, but
varies in breadth; it is placed at rather less than its own width
from the basi-scutal angle; its lower end is obliquely rounded; the
basal margin on the opposite sides of the spur, together form a
nearly straight line. The whole valve is rather broad. The crests for
the tergal depressores are barely developed.

The _Compartments_ have rather large parietal tubes; the septa are
coarsely denticulated at their bases; the internal lamina is smooth,
except close to the basis. The _radii_ have their summits parallel
to the basis; their sutural edges are formed of rather thick septa,
which stand at an unusual distance apart from each other, and have
perfectly symmetrical, minute denticuli on each side. The interspaces
between the septa are filled up solidly to within a short distance of
the surface; but yet not so completely as in the following species,
and as in those in the succeeding sections of the genus; this is what
might have been expected from the close affinity of _B. stultus_ to
_B. Ajax_, in which latter the radii are still permeated by pores,
though smaller than is general in the species of our first section
(A). The _alæ_ have their summits extremely oblique, and their
sutural edges, I believe, smooth. _Basis_ porose, with an underlying,
finely-cancellated layer.

_Mouth_: labrum with six small teeth; mandibles with the 3d tooth
blunt; the 4th minute, and the 5th almost confluent with the inferior
angle. Maxillæ with the edge straight and simple. _Cirri_ partly
destroyed; on each segment of the sixth pair there were five pairs of
spines.

10. BALANUS CALCEOLUS. Pl. 3, fig. 3 _a_-3 _e_.

BALANUS CALCEOLUS KERATOPHYTO INVOLUTUS (?) _Ellis._ Phil. Trans.,
vol. 50 (1758), Tab. 34, fig. 19.

LEPAS CALCEOLUS (?) _Pallas._ Elench. Zooph., p. 198, (sine
descript.) (1766).

CONOPEA OVATA (?) _J. E. Gray._ Annals of Philosophy, vol. x, 1825.

_Parietes and basis porose. Scutum with the pit for the lateral depressor muscle small and deep._

_Hab._--Attached to Gorgoniæ, West Coast of Africa. Tubicoreen, near
Madras, (Dr. Johnston), associated with _B. navicula_. Mediterranean
(?). Mus. Brit., Cuming, Stutchbury.

_Fossil._ Coralline Crag; Mus. S. Wood.

I must premise, with respect to the nomenclature of this and the three following quite distinct species, that in the published descriptions no allusion is made to any one of the characters by which alone they can be distinguished: hence I have been guided by geographical probabilities in assigning the specific name of _calceolus_ to the present species, as Ellis's specimens came from the Mediterranean; and that of _galeatus_ to the North American and West Indian specimens, as Linnæus' original specimens (according to a statement by Spengler) came from the West Indies. I have assigned new names to the two remaining East Indian species. I may here add that Spengler ('Skrifter af Naturhist.' 1 B, tab. 6, fig. 3, 1790) has described, under the name of _B. cassis_, an allied form attached to the _Gorgonia placomus_ from the seas of Norway; but I do not believe that it is the same with our present species.

_General Appearance._--The degree of elongation of the shell in
its rostro-carinal axis varies considerably (3 _a_, 3 _b_): the
elongation is due to the production of the rostrum and of the
corresponding end of the basal cup. These two portions of the
shell always form together an angle, and sometimes an acute angle,
whereas in all the many specimens which I have seen, the carina and
the carinal end (or heel) of the basis together form a straight
line; yet I should not be surprised if this end of the shell was
sometimes produced. The surface of the shell is smooth, or sometimes
marked with very minute projecting points: it is almost always
covered by the horny bark of the Gorgonia. The colour is either dull
purplish-red or dull purple, with obscure longitudinal stripes,
and often more or less transversely banded with white. The rostrum
is either white or very feebly tinted, being always paler than the
rest of the shell: the radii are usually paler than the parietes,
and are sometimes white: the carinal end of the basal cup is tinted
of the same colour with, but rather paler than, the compartments.
The orifice is rather small compared to the shell, and nearly
heart-shaped. The carino-lateral compartments are about one-third of
the width of the lateral compartments. The shell is very strong, and
the sutures resist the action of boiling caustic potash. The largest
specimen which I have seen was .7 of an inch in extreme length, and
under .25 in extreme breadth.

_Structure of the shell and basis._--The parietes are permeated by
quite distinct pores,--a character sufficient by itself to separate
this from the following species; the longitudinal septa forming the
tubes are slightly denticulated at their bases. The radii have their
summits quite square, extending from apex to apex of the adjoining
compartments. The alæ have oblique summits. The sutural edges of
the radii have approximate septa, which are obscurely denticulated:
the interspaces are filled up solidly, so that the radii are not
porose. The basis is distinctly porose, by which this species can be
distinguished from _B. navicula_ and _cymbiformis_. The basis has a
deep furrow on the under side, from clasping the thin horny axis of
the Gorgonia: the basal point of the rostrum is also notched from the
same cause, and, as a consequence, its upper surface becomes slightly
furrowed along its whole length.

The _Scuta_ have an articular ridge but moderately prominent, and
only slightly reflexed; the basi-tergal corner is rounded off; there
is no adductor ridge; there is a small, rather deep, distinct pit
for the lateral depressor muscle. _Terga_; externally the surface is
considerably depressed in the line of the spur. The spur is between
half and one-third of the width of the valve: its lower end is square
and truncated, or in some degree rounded; it is sometimes (3 _e_)
dentated with a few, minute, sharp teeth. The articular ridge is but
slightly developed; the crests for the depressor muscle are very
feeble.

_Animal's body_ unknown.

11. BALANUS GALEATUS. Pl. 3, fig. 4 _a_-4 _c_.

LEPAS GALEATA (?) _Linnæus._ Mantissa altera Holmiæ, 1771.

CONOPEA ELONGATA. _Say._[90] Journal of Acad. Nat. Sci. Philadelphia,
vol. ii, part 2, p. 323, 1822.

[90] If I have assigned the specific title of _galeatus_ to
the wrong species, yet Say's name of _elongatus_ ought not
strictly to be admitted; as the _Lepas elongata_ of Gmelin is a
Balanus,--probably a variety of _Balanus crenatus_. I may add, that
as the _Lepas galeata_ of Schröter ('Einleitung in die Conch.'
&c.), was attached to a Gorgonia from the East Indies, it cannot be
our present species, but probably is one of the three other allied
species, which all occur in India.

_Parietes not porose; basis porose. Tergum, with the apex square, caused by the great development of the articular ridge._

_Hab._--Charlestown, South Carolina; Florida; West Indies; Central
America; attached to Gorgoniæ; Mus. Brit., Agassiz, Cuming,
Stutchbury.

_General Appearance._--This and the two following species come so
close in general appearance to the last, that it will be quite
superfluous to do more than describe the few points of difference.
The shell and basis are generally quite as much elongated as in the
last species, and sometimes much more so, owing to the carinal end
(fig. 4 _a_), with the corresponding portion of the basal cup, being
produced like the rostral end, into a flattened, sharp point: I have
seen a specimen in this state .9 of an inch in length, and only .25
in breadth in the broadest part. In many specimens, however, the
shape is exactly as in _B. calceolus_; but the rostrum seems less
usually furrowed from clasping the stem of the Gorgonia. The colour
is paler, pinker, and more distinctly striped longitudinally than
in _B. calceolus_; I have, however, seen some not-striped, purple
specimens (and one transversely freckled with white) from the West
Indies. The parietes are strongly-ribbed internally, and are not
permeated by pores. The radii have their sutural edges crenated. The
basal cup is permeated by pores.

The _Scutum_ differs from that in the last species, only in the pit
for the lateral depressor muscle, being much shallower, and less
defined, and in the apex being truncated. The _Tergum_ is remarkable
from its broad, square, truncated summit, which underlies the whole
broad apex of the scutum: the square summit of the tergum is formed
by a great and peculiar development of the uppermost part of the
articular ridge. The spur is a little narrower than in _B. calceolus_.

_Mouth_: on the crest of the labrum there are two teeth on each side
of the central notch. The mandibles have five teeth, of which the two
lower are very small. The maxillæ show a trace of a notch under the
upper large pair of spines; near the inferior angle there are two
long spines. _Cirri_: in the first pair, one ramus is nearly twice as
long as the other: the segments are not very protuberant. There is
a sharp point at the dorsal basis of the penis. The branchiæ are of
moderate size, and plicated on one side.

12. BALANUS CYMBIFORMIS. Pl. 3, fig. 5 _a_, 5 _b_.

_Parietes and basis not porose. Scutum and Tergum with very small articular ridges. Tergum broad, almost equilateral._

_Hab._--Attached to a Gorgonia, Tubicoreen, near Madras, (Dr.
Johnston). Hab. unknown, Mus. Cuming.

_General Appearance._--I have seen only two specimens, kindly sent me
by Dr. Johnston, and a single specimen in Mr. Cuming's collection.
In most points this species agrees with the two last species. The
shell (excepting the rostrum), and even the opercular valves in Mr.
Cuming's specimen were of a very fine purplish-red; in the other
specimens they were feebly tinted purple. The parietes are strongly
ribbed internally, and are not permeated by pores. The basal cup is
not porose, but its inner surface is ribbed in lines radiating from
the centre, and in both these respects this species differs from the
two foregoing. The Radii are rather narrow; they are paler coloured
than the parietes; they have their sutural edges plainly crenated.
The alæ have extremely oblique summits; the narrow rim added during
the diametric growth of the shell is white, the rest of the sheath
being, in Mr. Cuming's specimen, finely coloured like the parietes.
Basal diameter of the longer axis of the largest specimen, .4 of an
inch.

_Scutum_, rather narrow, with the basi-tergal corner much rounded
off; externally the lines of growth are little prominent. Internally,
the articular ridge is extremely little developed, and not at all
reflexed; there is no adductor ridge; there is a minute pit for the
lateral depressor muscle, placed almost on the edge of the valve.
The _Tergum_ is broad, forming (the spur being excepted) an almost
equilateral triangle. The articular ridge is remarkably little
prominent, and placed close to the scutal margin. The spur is nearly
half as broad as the valve, with its extremity or basal margin in one
case obliquely truncated, and in another case nearly square.

_Animal's body_ unknown.

13. BALANUS NAVICULA. Pl. 3, fig. 6 _a_-6 _d_.

_Parietes and basis not porose: carino-lateral compartments very narrow, and of nearly the same width from top to bottom: radii with their sutural edges smooth. Scutum externally striated longitudinally._

_Hab._--Attached to Gorgoniæ, Tubicoreen, Madras (associated with _B.
calceolus_), Dr. Johnston. Hab. unknown, Mus. Brit. and Darwin.

This is a very distinct form, though nearer to the foregoing than to the other species. Its separation from the sub-genus Acasta is quite artificial; its affinity to this sub-genus is shown by its weaker shell, non-porose parietes and basis; by the radii having their sutural edges smooth, and their summits not quite square; by the carino-lateral compartments being very narrow; by the less elongated basis, not furrowed, from not clasping the branches of the Gorgonia; and by the longitudinally striated scuta; nevertheless, from the similar habits, and from the graduated structure in the five foregoing species, it cannot be removed out of the genus Balanus. I have seen three sets of specimens of this species.

_General Appearance._--Shell, sometimes with the rostrum, and
sometimes with the carina, and corresponding portions of the basal
cup, elongated; but not, apparently, to so great a degree as in
the foregoing species; basis not furrowed, from not clasping the
branches of the Gorgonia. Colour pale blueish-purple, with the
radii whiter. The surface is studded with small calcareous points.
The carino-lateral compartments are very narrow, not more than one
tenth of the width of the lateral compartments; they are, moreover,
scarcely wider at the base than at the summit. The summits of the
radii are, apparently, a little oblique, or at least not so square as
in the foregoing species. The shell is not nearly so strong as in the
last three species; and the compartments separate by gentle force,
and from the action of caustic potash. The largest specimen was .4 of
an inch in basal diameter.

Internally, the parietes are not very strongly ribbed, or they are
almost smooth, and there are no pores. The basis is concave and
smooth within, and is not porose. The sutural edges of the radii are
quite smooth, or sometimes they exhibit, in the lower part, mere
traces of septa,--a character by itself sufficient to separate this
from the foregoing species. The alæ have oblique summits, and the
rather narrow portion added during the diametric growth of the shell,
is white.

The _Scutum_, externally (6 _d_), has raised striæ, radiating from
the apex; valve rather thick; internally, the articular ridge is but
slightly prominent, and its lower end is rounded off: the depression
for the lateral depressor muscle is slight; between this depression
and that for the adductor muscle, the surface of the valve is
prominent. _Tergum_, somewhat beaked; externally, the surface is
depressed in the line of the spur: the carino-basal margin slopes
towards the spur.

_Animal's body_ unknown.

_Section_ C.

_Parietes and basis permeated by pores. Radii not permeated by pores._

14. BALANUS TRIGONUS. Pl. 3, fig. 7 _a_-7 _f_.

_Parietes ribbed, mottled purplish-red; orifice broad, trigonal, hardly toothed. Scutum thick, with from one to six longitudinal rows of little pits. Tergum without a longitudinal furrow; spur truncated, fully one third of width of valve._

_Hab._--Java; East-Indian Archipelago; Peru; West Columbia;
California; Sydney; New Zealand. Mus. Brit., Cuming, Stutchbury,
Dunker, &c.

_General Appearance._--Shell conical, generally depressed; orifice
broad, triangular, almost equilateral; walls coloured or only mottled
with purplish-pink, having either irregularly branching, or regular,
longitudinal ribs, which are generally white. The radii are pale
pink, or nearly white: the opercular valves have either their upper
parts, or nearly their whole surface, clouded with pinkish-purple:
the epidermis is not persistent: the walls are moderately strong: the
largest specimen was one inch, but generally full-grown specimens are
about half an inch in basal diameter.

The _Scuta_ have the lines of growth highly prominent. From one to
five or six rows (7 _b_, 7 _c_) of nearly circular, or transversely
oblong, deep pits, extend down the middle of the valve; rarely there
is not even one row; in this latter case, the valve is not striated
longitudinally. These little pits are caused by one or more deep
longitudinal furrows, crossed by the lines, or rather ridges, of
growth. In the same group of specimens, I have seen individuals with
three, five, and six rows; and even a few specimens with only one
row, or none at all. The outline of the valve is elongated, with the
apex slightly reflexed: the inner surface is protuberant, sometimes
to a remarkable, but variable degree. The articular ridge is not
very prominent, but it extends fully half-way down the valve, and
generally ends in a small free point. There is a short adductor
ridge, and a deep narrow pit or cleft for the lateral-depressor
muscle. _Terga_, externally smooth, flat, with scarcely a trace of
a longitudinal furrow; spur broad (7 _e_, 7 _f_), varying from half
to one third of the width of the valve, with the end truncated,
situated either near or quite close to the basi-scutal angle. The
crests for the depressor muscles are moderately well developed.

_Compartments._--The parietal tubes are, in their upper parts, filled
up solidly, without transverse septa. The radii generally have their
summits slightly oblique, and this is almost always the case with the
radii of the rostrum; the other radii sometimes extend from tip to
tip of the parietes, and are parallel to the basis; rarely the radii
are considerably oblique. The septa of the radii are very obscurely
denticulated, and the interspaces between them are filled up solidly.
The alæ have their sutural edges thin and smooth.

_Mouth._--Labrum with three teeth close together on each side of the
central notch: mandibles with four teeth, the fourth being small, the
fifth either absent or scarcely distinguishable from the inferior
angle: maxillæ without any notch, with the two lower spines rather
longer than the others. _Cirri_: In the first pair, one ramus is only
half the length of the other; in the second pair, both rami are short
and about equal in length; in the posterior pairs, the segments,
which are not protuberant, bear four pairs of spines, of which the
three lower pairs are short.

This species is widely-distributed, and where found seems to be common. It is generally attached to shells of mollusca, but I have seen it also attached to wood. I have found it associated with _B. tintinnabulum, var. concinnus_, and _coccopoma_, with _B. psittacus_, _improvisus_ and _amphitrite_, and with _Elminius modestus_.

Young specimens bear a considerable resemblance to certain young varieties of _B. tintinnabulum_, and can indeed be distinguished from them only by a careful examination of the opercular valves; for it should be borne in mind, that in certain cases the scuta in _B. tintinnabulum_ are pitted with little cavities. This species in some respects is, I think, allied to _B. porcatus_, but it is far more closely related to _B. spongicola_, and can be discriminated with difficulty from certain varieties of this latter species. In Mr. Cuming's collection, there is a group of small specimens, crowded between some older specimens, which are remarkable from the shell being oval in a transverse section,--from the smoothness of the walls,--and from the absence of pits on the scuta; yet there could be no doubt that these specimens belonged to our present species.

15. BALANUS SPONGICOLA. Pl. 4, fig. 1 _a_-1 _d_.

BALANUS SPONGICOLA. _Brown's_ Illustrations of the Conchology of
Great Britain (1827), pl. 7, fig. 6: 2d edit. (1844), pl. 53,
figs. 14-16.

_Parietes generally smooth, sometimes longitudinally folded; coloured pink: orifice toothed. Scutum longitudinally striated. Tergum, with the apex produced, without a longitudinal furrow; spur truncated, about one third of width of valve._

_Var. with the walls slightly folded longitudinally._

_Hab._--South coast of England, and Tenby in South Wales, often
imbedded in sponges; attached also to shells and rocks in deep
water; Mus. Brit., Jeffreys. Algiers, on Mytili and Serpulæ, with
_B. perforatus_, Mus. Mac Andrew. Madeira, with _B. tulipiformis_,
Mus. Lowe. Lagulhas Bank, Cape of Good Hope, on detached kelp, with
_B. Capensis_, Mus. Sir J. Ross. Imbedded in sponge with _Acasta
spongites_, Mus. Bowerbank. _Var._ West Indies.

_Fossil_ in Coralline Crag, Mus. S. Wood.

_General Description._--Shell tubulo-conical; orifice of moderate
size, rather deeply toothed; colour dull pink, or purplish, or dark
flesh-colour; sometimes the radii are paler, sometimes of the same
colour with the parietes. Surface smooth when well preserved, having
transverse rows of minute spines. In the West Indian variety the
walls are slightly or much folded, but I will describe this form
separately. Size of largest specimen (Mus. Jeffreys), .6 of an inch
in basal diameter.