J. Ross, in the Southern ocean, and in another older set from an unknown
source, several parts of the outer tunic of the animal’s body presented
the remarkable fact of being calcified, but to a variable degree;
whereas in several specimens from California, there was no vestige of
this encasement. Considering it most improbable that the calcification
of the integuments should be a variable character, I most carefully
compared the above-mentioned sets of specimens, valve by valve, trophi
by trophi, and cirri by cirri, and found no other difference of any
kind; therefore I cannot hesitate to consider both to be the same
species. The first Southern specimen which I examined presented the
following characters: on the prosoma there was a central longitudinal
band, formed of a thin, brittle, brown-coloured calcified layer, which
became irregularly rather narrow towards the thorax; on each side it
sent out six or seven irregular rectangular plates, which surrounded and
supported the bases of the two rows of filamentary appendages; and
outside these, some of the papilliform projections also had their bases
surrounded by small, calcified, separate rings. The thoracic segments
corresponding with the second, fourth, fifth, and sixth cirri had, on
each side, an elongated calcified plate; on the ventral surface of the
thorax, between the first and second cirri, there were two minute
plates. In all the cirri, excepting the first pair, the segments of the
rami, and in the three posterior pairs, the segments of the pedicels,
had their dorsal surfaces strengthened by oblong, quadrilateral,
calcified shields, the upper margins of which are notched for the dorsal
tufts of spine, and the two lateral margins are also slightly hollowed
out; these are represented in figure 27. The lower segments of the
pedicels of some of the cirri, had an additional calcified plate on the
antero-lateral face.
These plates are of a faint-brown or yellowish colour, and are
conspicuous: the degree of calcification differs considerably; some are
quite brittle and very thin, others half horny, and effervesce only
slightly in acids. After having been placed in acid, there is no
apparent difference between the parts before occupied by the calcified
plates and the surrounding membrane; these plates, however, are not
superficial, but consist of several of the laminæ, which together
compose the ordinary integument, in a calcified condition. Like the
integuments of the body, and unlike the valves of the capitulum, these
calcified plates are thrown off at each exuviation. Neither the exact
shape nor number of the plates corresponded in different individuals,
nor even on opposite sides of the same individual. The margins of the
plates often have a sinuous corroded appearance; they are, moreover,
often penetrated by minute rounded holes, that is, by minute, rounded,
non-calcified portions. In one specimen from the Antarctic expedition,
there were only here and there a single shield on the segments of the
posterior rami, and no plate on the prosoma. Of two specimens in another
and older set in the British Museum, from an unknown locality, both had
shields on the segments of the cirri, but only one had the large plate
on the prosoma. I may here mention that in one specimen, in which the
calcified plates were most developed, and which was nearly ready to
moult, there were, within the filamentary appendages on the prosoma,
small irregular balls of calcareous matter, appearing to me as if
calcareous matter had been morbidly excreted, and not like a provision
for the future.
_Range._--This species, in the present state of our knowledge, seems to
range further than any other of the genus, extending from Upper
California, (lat. 32° to 35° N.,) across the Pacific, to at least 32°
S., perhaps much farther south, for it was collected during the
Antarctic expedition, and 32° was the highest latitude traversed by that
expedition.
_Affinities._--This species is closely related to _P. cornucopia_ and
_P. elegans_, but differs rather more from them, than these two do from
each other. In the capitulum the chief distinctive characters are--the
more perfect graduation in size, and the greater number, (taking
equal-sized specimens,) of the whorls of latera--the darker colours--the
central part of the basal margin of the carina in this species, being
considerably excised--the peculiar form of the basal margin of the
scuta--and lastly, the scutal margin of the terga being more hollowed
out. In the animal’s body, the most obvious distinctive character is the
uniarticulate caudal appendage. This species agrees with _P. elegans_,
in the presence of the singular elbowed teeth, on some of the spines in
the first three pairs of cirri.
4. POLLICIPES MITELLA. Pl. VII, fig. 3.
LEPAS MITELLA. _Linn._ Systema Naturæ, 1767.
POLLICIPES MITELLA. _G. B. Sowerby._ Genera of Shells, fig. 2.
POLYLEPAS MITELLA. _De Blainville._ Dict. Sc. Nat. (1824) Plate,
fig. 5.
CAPITULUM MITELLA. _J. E. Gray._ Annals of Philosoph., new series,
vol. x, 1825.
_P. capitulo valvarum unico sub-rostro verticillo instructo: laterum
pari superiore (introrsum spectanti) inferiorum magnitudinem ter aut
quater superante: lateribus inferioribus utrinque obtegentibus:
pedunculi squarmarum verticillis densis, symmetricè dispositis._
Capitulum with only one whorl of valves under the rostrum: the upper
pair of latera, viewed internally, are three or four times as large as
the lower latera, which overlap each other laterally: scales of the
peduncle symmetrically arranged in close whorls.
Maxillæ, deeply notched: caudal appendages, multi-articulated:
filamentary appendages, none.
Philippine Archipelago, Mus. Cuming: China Sea, Mus. Brit.:
Amboyna and East Indian Archipelago, according to Rumphius and
other authors: Madagascar, according to J. E. Gray.
_Capitulum_, compressed, consisting of the scuta, terga, carina,
rostrum, and a large pair of upper latera, with a single lower whorl of
smaller valves; these latter vary from 22 in very small specimens, to 26
in large specimens. The capitulum, therefore, is formed of at most 34
valves; but in the largest specimen seen by me, the capitulum being 2.3
of an inch in width, there were only 32 valves. In the smallest, namely,
with a capitulum .15 of an inch in width, there were 30 valves. The
valves are remarkably strong, and formed of white shelly matter; they
are closely approximate, and overlap each other: the scuta and terga are
articulated together by a fold; the apices of the valves are either worn
and disintegrated, or they project freely like horns beyond the sack, to
a much greater extent than in any other recent species of the genus:
even a considerable portion of the scuta projects obliquely upwards. The
exterior surfaces of the valves (when not worn) are covered by a strong
yellow membrane, and the upper free parts are generally attached
together for some little length by this same membrane. The valves are
plainly marked by the zones of successive growth; and most of them are
ribbed and furrowed slightly, from their umbones to their basal margins.
The yellow external membrane, examined microscopically, is marked by, or
rather formed of, numerous growth-lines, crossed by longitudinal beaded
ridges. The tubuli are not numerous, and of small diameter.
_Scuta_ (Pl. VII, fig. 3 _a´_, _a_) triangular, with the apex more or
less produced, according to the state of its preservation, and a little
curved towards the terga; basal margin, and in some degree the
tergo-lateral margin, arched, and slightly protuberant; occludent margin
thickened, slightly prominent, with the inner edge covered by the
yellow membrane, like the exterior surface of the valve. The upper part
of the tergo-lateral margin overlaps a little the edge of the tergum,
and receives it in a furrow,--the two valves being thus locked together.
This furrow lies in the freely-projecting, membrane-covered portion, and
extends up to the apex; it is of variable depth. Internally the scuta
are concave, and in some old specimens to a high degree. In these
latter, the basal margin, towards the tergo-lateral side, is strongly
sinuous; the prominences are formed by the terminations of the external
longitudinal ridges, and correspond to the interspaces between the
valves of the lower whorl. These ridges, which are interesting, from
throwing light on similar ridges in some fossil species, are present,
both on old and young specimens, and run from the apex of the valve, in
a slightly curved line, to the tergo-lateral half of the basal margin,
where, as we have just seen, they sometimes form prominences. They
consist of three or even four obscure, almost confluent, ridges, of
which the middle one is generally (but not always) the smallest:
together they cover the whole of that part of the scutum, which is not
overlapped along the basal margin by the rostrum and large upper latus;
and they seem evidently due to the growth of the shell in this
interspace having been freer. So, again, the three or four small,
confluent, component ridges have the same relation to the interspaces
between the small latera of the lower whorl.
_Terga_ large, four-sided, with the internal growing surface (fig. 3
_a´_ _b_), almost diamond-shaped; basal angle blunt, rounded;
exteriorly, from the apex to the basal angle there is a rather broad,
very slight prominence, which bears the same relation to the carina and
upper latus, as do the compound ridges on the scuta to the rostrum and
upper latus. The upper part of the scutal margin forms a
slightly-projecting, rounded shoulder, though variable in its degree of
prominence, in relation to the variable depth of the recipient furrow in
the scuta. Externally, parallel to the occludent margin, and close
below the prominent shoulder, just mentioned, there is a slight and
variable depression, extending up to the apex of the valve. This
depression is due to the prominence, variable in degree, of the tergal
edge of the recipient furrow in the scuta.
_Carina_, triangular, strong, inwardly bowed, generally with a large
upper portion freely projecting; exteriorly with a narrow, sharp,
central ridge or keel, which is solid, the interior concavity not
reaching so deep; inner growing surface (fig. 3 _b´_, _b_) deeply
concave, triangular. Basal margin square--that is, transverse to the
longer axis of the carina, or it even rises (as is best seen in the
growth-ridges) a little towards the exterior keel. On each side of the
central exterior keel, there is a narrow longitudinal ridge,
corresponding with the interspace between the sub-carina and the
next-but-one latus of the lower whorl; the latus next to the sub-carina
is very small, and overlies the ridge itself. In a very large specimen,
these lateral longitudinal ridges formed (as they likewise did on the
rostrum) slight prominences on the basal margin. In one specimen the
carina was straight.
_Rostrum_ closely similar, in almost every respect, to the carina, even
to the exterior, lateral, longitudinal ridges, and in their relation to
the interspaces in the lower whorl. The valve is generally not so long,
but rather wider, more inwardly bowed, and with the exterior solid keel
less prominent than in the carina. The inner growing surface (fig. 3
_b´_ _d_) is less acuminated at its upper end.
_Upper pair of Latera._--These are much larger than the remaining valves
of the lower whorl; they are straight, triangular, and much acuminated,
with their apices, when well preserved, extending far up, for fully
three fourths of the height of the scuta. They nearly equal in length
the carina. The growing surface (fig. 3 _b´_, _a_) is flat, triangular,
in well-preserved specimens forming only a third or a quarter of the
entire length of the valve. In the middle of the basal margin there is a
very slight prominence, corresponding with a slight external central
ridge, formed as heretofore by the overlapping of two of the valves of
the lower whorl. Basal margin nearly on a level with that of the scuta
and with the basal points of the terga. The foregoing eight larger
valves form the main cavity, in which the body of the animal is lodged.
_Valves of the Lower Whorl._--These, seen externally, seem to belong to
more than one whorl, but internally their basal margins stand on a
level. They vary in number, as already stated, from 22 to 26. I have
seen an individual with a valve more on one side than on the other. They
are of unequal sizes, but they are rather variable in this respect: the
largest are not above half the size of the upper latera: three or four
pairs, together with the sub-rostrum (_e_) and sub-carina (_c_), are
always larger than the others: these two latter valves differ from the
others only in being more concave. Seen externally, all these valves
project considerably, and curl a little inwards, with their apices
generally worn and truncated. Viewed internally (fig. 3 _b´_), whilst
the valves are in their proper places, the inner and growing surfaces of
the smallest are seen to be triangular,--of the larger, some are
rhomboidal, and others quadrilateral with the upper side much longer
than the lower. These latter valves overlap the upper parts of the
little valves on both sides of them; the rhomboidal valves overlap a
valve on one side, and are overlapped on the other; the triangular
valves are overlapped on both sides.
The corium lining the capitulum is produced into narrow purple crests,
which enter the interstices between the valves, more especially along
the line separating the upper and lower whorls. There is, also, a
distinct flattened, tapering, free projection of corium, which enters
between the carina and sub-carina; and another between the rostrum and
sub-rostrum.
_Peduncle_, much compressed, short, rarely as long as the capitulum; in
one very large specimen it was extremely short, barely one fifth of the
length of the capitulum. The attached portion, which is moderately
pointed in young specimens, becomes extremely broad in old specimens.
The calcified scales sometimes differ a little in size, in specimens of
the same age: they are always compactly and symmetrically arranged: in
old specimens they are much larger than in young ones: each scale has,
at first, a transversely elliptic growing base, which ultimately becomes
nearly circular. Exteriorly the tips of the scales are always
disintegrated; they are sometimes club-shaped, owing to the scales
having been re-added to after a period of reduced growth. The scales are
fringed with brown disintegrating membrane.
_Attachment._--At the base of the peduncle, the two cement-ducts running
together, twist about in a singular manner, and at their bends pour
forth cement. According to the age of the specimen, the ducts vary in
diameter from 1/2000th to 5/2000ths of an inch. The two cement glands
are small and difficult to find; they are retort-shaped, with two
ovarian tubes entering each. They lie close together, in nearly the
centre of the peduncle, and less than half-way down it. This proximity
of the two cement-glands, and their position low down the peduncle, are
of interest in relation to the position of these same glands in the
sessile Cirripedes.
_Size and Colours._--This is the largest and most massive species in the
family. I have seen one specimen in the British Museum, from the Coast
of China, 2.3 inches across the capitulum, and 1.5 in length, with the
valves surprisingly thick. The relative width and length of the
capitulum varies. The sack (in specimens long kept in spirits) is dirty
purple, and exteriorly between the scuta, dark purple. The cirri,
trophi, penis, caudal appendages, three posterior segments of the
thorax, and the abdominal surface are dark-brownish purple.
_Body._--Thorax remarkably compressed and carinated; prosoma pretty well
developed. Extending from the base of the second cirrus, to nearly a
central line on the thorax, there is on each side a rounded ridge: there
is a second transverse ridge, running from the base of the first cirrus
to near the adductor scutorum muscle: these ridges seem formed merely to
allow of the larger development of the testes.
_Mouth._--Labrum highly bullate; crest without any teeth, but with a few
minute hairs. The inner fold of the labrum forming the supra-oesophageal
cavity, is thickened, and shows a trace of a central line of junction,
as in Sessile Cirripedes.
_Palpi_ (Pl. X, fig. 7), small; of a singular club-like shape, owing to
the convexity of the outer margin; exterior spines long, all doubly
serrated.
_Mandibles_ (Pl. X. fig. 1), with five teeth, of which the second is
very small; inferior angle coarsely pectinated.
_Maxillæ_ (fig. 14), with a deep narrow notch (bearing some fine spines)
beneath the two upper great spines, which stand on a prominence; edge
straight, bearing fourteen or fifteen pairs of spines: on the inferior
angle there is an obscure tuft of shorter and finer spines: apodeme
long, sinuous, and slender.
_Outer Maxillæ_ (fig. 17), with the inner margin divided by a deep notch
into two lobes, of which the upper one is rather short; both are clothed
with a compact row of short bristles; exterior margin with longer
bristles.
_Olfactory Orifices_, large and prominent to an unusual degree.
_Cirri_, moderately long and curled; the four posterior pair are alike;
each segment has its anterior face somewhat protuberant, and bears six
pairs of long spines, with a rather large, narrow tuft of intermediate
spines, some of which are finely and doubly serrated. The dorsal tufts
consist of short, thick spines, with some fine longer ones. The first
cirrus is seated near the second; its rami are slightly unequal in
length; lower segments paved with bristles; one ramus is thicker than
the other, and some of its segments have coarsely pectinated spines.
Second cirrus has the five basal segments of its anterior ramus highly
protuberant, and paved with bristles, of which some are coarsely
pectinated; the basal segments of the posterior ramus are rather more
thickly clothed with bristles than are the posterior cirri, but
otherwise resemble them. The third cirrus, as already stated, is exactly
like the three posterior pairs; and this is a very unusual circumstance.
On the dorsal surfaces and sides of the pedicels of the posterior cirri,
there are some scattered, short, thick, minute spines.
_Caudal Appendages_, multi-articulate: in a medium-sized specimen, each
contained eight segments, which reached half-way up the upper segment of
the pedicel of the sixth cirrus. Lower segments flattened; the upper,
tapering, and cylindrical; all have their upper margins furnished with
stiff, little spines. In a young specimen (only .3 of an inch in length,
including the peduncle), the caudal appendage contained only four
segments, and the tip did not reach to the upper edge of the lower
segment of the pedicel of the sixth cirrus.
_Stomach_, without cæca.
_Generative System._--Vesiculæ seminales not reflexed at their broad
ends; white, spotted with black. Testes, pear-shaped, borne on long
footstalks: penis covered with minute bristles, in little tufts arranged
in straight lines. The ovarian tubes fill up the peduncle to its base,
but do not surround the sack; they are of small diameter, and simply
branched. There is a very narrow ovigerous frænum, with a straight edge,
lying on each side under the line of junction between the scutum and
upper latus.
_Affinities._--This species differs from all the others of the genus, in
the third cirrus resembling exactly the three posterior pairs. In most
of its characters--namely, in the symmetrical arrangement of the scales
on the peduncle, in the considerable size of the valves of the lower
whorl, in the general approximation of the valves, in the
multi-articulated caudal appendages, in the form of the outer maxillæ,
in the prominent olfactory orifices, in the basal segments of the
anterior ramus alone of the second cirrus being paved with bristles,
there is more affinity to _P. cornucopia_, _P. elegans_, and _P.
polymerus_ than to _P. sertus_ and _P. spinosus_.
In the scuta and terga being articulated together, in the union of all
the valves by stiff membrane, in the peculiar manner in which the valves
of the lower whorl overlap each other, in the corium entering between
some of the valves in filiformed appendages, in the near equality of
size of the rostrum and carina, in the shortness of the peduncle in old
specimens, in the position of the cement-glands, and lastly in the
characters of the third pair of cirri, this species presents a closer
affinity to the sessile Cirripedes, more especially to the Chthamalinæ,
than does any other species of any other genus amongst the Lepadidæ. The
movements, however, of the four opercular valves are not at all more
independent of the other valves, than in the other Pedunculated
Cirripedes; and the peduncle is furnished with all its characteristic
muscles.
5. POLLICIPES SPINOSUS. Pl. VII, fig. 4.
ANATIFA SPINOSA. _Quoy_ et _Gaimard_. Voyage de l’Astrolabe. Pl.
xciii, fig. 17.
_P. capitulo valvarum uno aut pluribus sub-rostro verticillis instructo:
laterum pari superiore vix inferioribus longiore: membranâ valvas
tegente (post desiccationem) subfuscâ flavescente: pedunculi squamis
inæqualibus, non symmetricis: verticillis longiusculè distantibus._
Capitulum with one or more whorls of valves under the rostrum: upper
pair of latera only slightly larger than the lower latera: membrane
covering the valves (when dried) light yellowish-brown: scales of the
peduncle of unequal sizes, unsymmetrical, arranged in rather distant
whorls.
Maxillæ, with the edge square and straight: caudal appendages
uniarticulate: filamentary appendages, none.
New Zealand. Mus. Jardin des Plantes, Paris: Mus. Cuming.
_Capitulum_, flattened, triangular, broad, with the valves varying in
number, in full-grown specimens of the same size, from 30 to above 60;
the scuta, terga, and carina are very much larger than the other valves;
the rostrum, however, is nearly half the size of the carina; the
remaining valves are exceedingly small. In some specimens there is only
one whorl under the carina; in other specimens there are distinctly two
whorls. The scuta, terga, and carina stand pretty close together; they
are moderately thick, and are covered, in chief part, by yellowish-brown
membrane, which is destitute of spines.
_Scuta_, triangular, broad, basal margin slightly protuberant.
_Terga_, as large as the scuta, flat, regularly oval, basal point blunt
and rounded.
_Carina_ very slightly curved, triangular, internally rather deeply
concave, basal margin straight. The inner and growing surface is four
fifths of the entire length of the valve. In half-grown specimens the
apex projects a little outwards.
_Rostrum_, small, much curled inwards; the basal margin is much hollowed
out; the inner surface is broadly triangular, more than twice as wide as
high, and about one fourth of the entire length of the valve. The
remaining valves, about 26 in number, do not correspond on the opposite
sides of the same individual, they are exceedingly small, with the
sub-carina, sub-rostrum, and three pairs of latera a trifle larger than
the lower latera, which are generally arranged in two whorls. In shape
all the latera are nearly alike; they consist of flattened styles, with
their inner surfaces transversely oval, and more or less elongated, the
larger ones being most elongated.
_Peduncle_, broad, barely as long as the capitulum. The calcareous
scales are irregularly shaped, minute, elongated and pointed, placed in
separate transverse rows, and crowded together in each row. Only the
scales in the uppermost row grow regularly; but some of the lower scales
continue to be added to irregularly, and hence are the largest. On the
other hand, the lower part of the peduncle, from the first formed scales
having been worn away, is often quite naked. From this cause, and from
the continued and irregular growth of some of the lower scales, the rows
in this part of the peduncle, generally become irregular. The surface of
attachment is broad.
In a half-grown specimen, with a capitulum only 3/10ths of an inch long,
all the lower valves were considerably larger in proportion to the
scuta, terga, and carina, than in full-grown individuals.
_Size and Colours._--Length of capitulum in the largest specimen,
7/10ths of an inch; breadth, slightly exceeding the length. Colours
after having been long in spirits--upper part of sack, thorax, pedicels
of cirri, and penis, clouded with fine purple; cirri banded with the
same; exterior convex surface of the outer and inner maxillæ and palpi
dark purple; prosoma yellow. The membrane of the peduncle and of the
capitulum is dirty yellow, with bands of purple between some of the
valves.
_Filamentary Appendages_, none. Ovigerous fræna placed near the middle
of the basal margin of the scuta; small, semi-oval, with an elliptical
ring of bead-like glands; glands seated on long footstalks.
_Mouth._--Labrum far produced towards the adductor muscle; upper part
highly bullate, nearly equalling the longitudinal diameter of the rest
of the mouth, and very slightly overhanging the lower part; crest with
very minute bead-like teeth.
_Palpi_, with their inner margins considerably excised, most thickly
clothed with spines.