A Monograph on the Sub-class Cirripedia Part 29

_P. capitulo, valvarum duobus aut pluribus sub-rostro verticillis instructo: valvis et pedunculi squamis rufo-aurantiacis: squamarum verticillis densis symmetrice dispositis._

Capitulum with two or more whorls of valves under the rostrum: valves and scales of peduncle reddish-orange; the latter symmetrically arranged in close whorls.

Maxillae with three tufts of fine bristles, separated by larger spines; segments is in the first cirrus more than half the number of those in the sixth cirrus; caudal appendages multi-articulate; filamentary appendages attached to the prosoma.

Coast of Peru, Payta, attached to wooden posts, according to Lesson: Lobos Island, Peru, Mus. c.u.ming: West Coast of Mexico, Tehuantepec, on an exposed rock, according to Hinds.

The resemblance of this species is so close to _P. cornucopia_, that it is quite useless to do more than point out the few points of difference.

Valves of the capitulum and scales of the peduncle, coloured (after having been in spirits,) reddish-orange. In a specimen in which the capitulum was 1.3 of an inch in length, there were three whorls of valves below the carina; in this large specimen altogether there were about eighty valves; in medium-sized specimens, the number is about the same as in _P. cornucopia_. The upper latus, (viewed internally,) has an area about twice as large as that latus, which corresponds to the inters.p.a.ce between the carina and terga; whereas in _P. cornucopia_ the upper latus is only slightly larger than this same valve. The apex of the basal internal margin of the carina is here rounded, instead of being square, as is generally the case with _P. cornucopia_. The strong membranous margin of the orifice of the sack, in its upper part, is almost one third as wide as the widest part of the terga, whereas in _P.

cornucopia_ it is only one fourth of this same width. The peduncle apparently is rather longer, compared with _P. cornucopia_, and the calcareous scales on it perhaps a little larger in proportion.

In a very young specimen, with the capitulum barely exceeding 1/20th of an inch in length, I could distinguish the sub-rostrum, sub-carina, the upper, and some of the lower latera.

_Filamentary Appendages._--These, in a medium-sized specimen, are arranged on the prosoma in four longitudinal approximate rows, there being twelve in each row; those in the two outer rows are only half the length of those in the two inner rows; those nearest the thorax are the longest; there are some papillae outside the outer rows. In a very large specimen with its capitulum 1.3 in length, these filaments were very much more numerous, and some were placed on the first segment of the thorax, and at the bases of several of the posterior cirri. Some of the filaments are bifid, trifid, and even branched. In all the specimens, at the bases of the first pair of cirri, there are, on each side, a pair of filaments, (one below the other,) pointing upwards, less than half as long as those on the prosoma: also on each side of the mouth, there is a longer and thicker filament, pointing upwards, with a few very minute scattered spines on it; the apices of these three pair of filaments, as well as of some of the others, are roughened with very minute pectinated scales. All these filaments were gorged with the branching testes.

_Mouth._--The parts are closely similar to those in _P. cornucopia_; in the mandibles, the inters.p.a.ce between the third tooth and the inferior angle, is slightly pectinated: in the maxillae, there are six or eight pairs of spines between the two upper tufts of fine spines.

_Cirri._--These are in most respects similar, to those of _P.

cornucopia_. In a specimen in which the sixth cirrus had eighteen segments, the shorter ramus of the first pair had ten segments, of which the five lower segments were thick and clothed with doubly serrated spines. In the second cirrus the anterior ramus had fifteen segments, of which the four basal ones were highly protuberant, and thickly clothed with spines. These spines, and some on the third cirrus, and a few on the first cirrus, have peculiar bent teeth, presently to be described under _P. polymerus_. These singularly toothed spines are absent in _P.

cornucopia_. From the above numbers, we see that the first and second pairs of cirri have more segments in proportion to the sixth pair, than in _P. cornucopia_; and in the second pair, a fewer proportional number of the basal segments are protuberant and thickly clothed with spines.

_Caudal Appendages_, shorter than the lower segments of the pedicels of the sixth cirrus, with only four articulations; rather constricted near the base.

The _Ovigerous Fraena_ consist of very long and prominent folds, thinning out to nothing towards the bases of the scuta, but not furnished, as far as I could see, with glands, and therefore not normally functional.

_Diagnosis with P. cornucopia._--The reddish-orange colour of the valves alone suffices. There is a very slight difference, in the larger proportional size of the upper latera, and in the outline of the basal margin of the carina. In the maxillae there is, in _P. elegans_, a greater width between the two upper tufts of fine spines. In the cirri, the segments in the first pair, are more than half as many as those in the sixth pair; in the anterior ramus of the second pair, only 4/15ths of the segments are protuberant and brush-like, whereas in _P.

cornucopia_ 5/12ths are in this condition.

3. POLLICIPES POLYMERUS. Pl. VII, fig. 2.

POLLICIPES POLYMERUS.(!) _G.B. Sowerby._ Proc. Zool. Soc., 1833, p. 74.

--MORTONI. (!) _Conrad._ Journal Acad. Nat. Sci. Philadelphia, vol. vii, p. 261, Pl. xx, fig. 12, 1837.

_P. capitulo, valvarum duobus, tribus, aut pluribus sub-rostro verticillis instructo: valvis sub-fuscis: lateribus a supremo ad infimum gradatim quoad magnitudinem positis: carinae margine basali (introrsum spectanti) ad medium excavato: pedunculi squamarum verticillis densis, symmetrice dispositis._

Capitulum with two, three, or more whorls of valves under the rostrum: valves brownish: latera regularly graduated in size from the uppermost to the lowest: carina with the basal margin, (viewed internally,) hollowed out in the middle: scales of the peduncle symmetrically arranged in close whorls.

Maxillae with three tufts of fine bristles, separated by larger spines; caudal appendages uniarticulate; filamentary appendages attached to the prosoma.

Upper California, St. Diego and Barbara, 32 to 35 N., according to Conrad; Mus. c.u.ming: Low Archipelago, Pacific Ocean; Mus. Coll. of Surgeons: Southern Pacific Ocean, collected during the Antarctic Expedition, Mus. Brit.

_Capitulum_, but little compressed, broad, with the scuta and terga placed in a more oblique direction, with respect to the peduncle, than is usual, so that the line of orifice forms an unusually small angle with the basal margin of the capitulum. The capitulum is composed of several whorls of valves, which gradually decrease in size from above downwards. In a medium-sized specimen there were four whorls under the rostrum; in the lowest of these whorls, there were between eighty and ninety valves, and in the whole capitulum from one hundred and seventy, to one hundred and eighty. The valves in the lower whorls are not of equal sizes. Viewed externally, the valves seem to touch and overlap each other; viewed internally (Pl. VII, fig. 2 _a_) they are found to be just separated from each other by transparent membrane; none of the valves are articulated together. The outer surfaces of nearly all the valves, except in the two last formed whorls, are much disintegrated, and seem to be composed of alternate white and brown layers of sh.e.l.l.

The membrane connecting the valves, as well as that of the peduncle, (in specimens long kept in spirits,) is brown; but in some dried specimens, there are indications of its having been coloured crimson (as in _P.

cornucopia_), round the orifice and between the valves.

_Scuta_, irregularly oval, convex, narrow at the upper end; basal margin may be almost said to be formed of three short, unequal margins, corresponding with the rostrum, the rostral and the adjoining latus. The edge corresponding with the latter, is the best marked, and is generally slightly hollowed out, as if a piece had been broken off. The tergo-lateral margin is curved and protuberant. The umbo projects a little over the scutal margin of the terga.

_Terga_, projecting beyond the other valves to an unusually small degree, broadly oval; basal angle bluntly pointed, apex rounded, blunt; scutal margin, hollowed out to receive the upper part of the tergal margin of the scuta; carinal margin curved and protuberant; occludent margin consists of two short sides at right angles to each other. The whole valve in length and area is about equal to the scuta; internally, somewhat concave.

_Carina_, triangular, rather narrow, internally deeply concave, very slightly curled inwards; basal margin protuberant, with a large central portion considerably hollowed out.

_Rostrum_, triangular, of nearly the same shape as the carina, but only one third of its length, internally very slightly concave, and with the basal margin various, being either truncated or angularly prominent in the middle.

_Latera._--The upper pair (corresponding to the interval between the scuta and terga) is only a trifle larger than the latera immediately beneath; and these only a little larger than those lower down. In the lowest whorl, the valves are very minute, though still about twice as large as the scales on the peduncle, and of a different shape from them.

The upper latera (viewed internally) are almost diamond-shaped, owing to the prominence of the basal margin, but this varies considerably in degree. The latera in the next whorl are triangular, with the basal margins protuberant and arched, in a less and less degree in the lower whorls, until in the lowest, the valves are elongated transversely.

_Microscopical Structure._--A valve placed in acid leaves a thick opaque ma.s.s, formed of three different kinds of tissue, one having a finely shaded appearance; a second with a largely hexagonal reticulated structure, and the third thin, transparent, and marked with arborescent lines, which I imagine to be tubes, as will be hereafter seen in Lithotrya. Near the exterior surface, there are many tubuli. It appears to me probable that the strong tendency which the valves in this species have to disintegrate, is connected with the unusual quant.i.ty of animalized tissue contained by them. Externally the valves are covered by a strong membrane, either white or yellow, or white streaked with yellow, and marked by lines of growth, and by longitudinal, sinuous, little ridges.

_Peduncle_, in the upper part, of rather less diameter than the capitulum; twice or thrice as long as it; tapering a little downwards; surface of attachment wide and flat. Calcareous scales, minute, symmetrically and closely packed together: each scale is much flattened, and its shape, including the imbedded portion, is that of a spear with its point broken off. The basal end of each scale is conically hollow, and from the layers of growth conforming to this hollow, there is a false _appearance_ of an open tube running through the scale.

_Attachment._--The surface of attachment is wide: the two cement-ducts, after running down the sides of the peduncle in a sinuous course, within the longitudinal muscles and close outside the ovarian tubes, pa.s.s through the corium, and then separately form the most abrupt loops or folds. These are represented in Pl. IX, fig. 2, in which a s.p.a.ce about 1/10th of an inch square is given, as seen from the outside. At each of the bends, an aperture has been formed through the membrane of the peduncle, and cement poured forth. The manner in which the discs of cement (_b_) come out of the two ducts (_a_ _a_), and reach the external surface, is shown in the section, figure 2 _a'_. The two tubes are firmly attached to the older layers of membrane, and are covered by the last-formed layers. In a young specimen, the cement-ducts were a little above 2/2000ths of an inch in diameter, which had increased, in a medium-sized specimen, to 5/2000. The cement-glands are retort-shaped, seated near each other, high up in the peduncle.

_Size._--The largest specimen which I have seen, was three inches in length including the peduncle; the capitulum was 9/10ths of an inch long, and one in width.

_Young Specimen._--I examined one with a capitulum 18/1000ths of an inch long, measured from the lowest whorl to the tips of the terga; the width was only 13/1000ths of an inch; in old specimens the width of the capitulum is greater than the length. The length of one of the scuta was 14/1000ths of an inch, therefore, greater than the width of the entire capitulum, which is not the case with mature specimens. Besides the scuta and terga, the carina and rostrum, and three pair of large latera, there was a lower whorl formed of ten or twelve valves, giving altogether to the capitulum of this very small specimen, either twenty-two or twenty-four valves.

_Shape of Body, Sack, Colours, &c._--From the position of the orifice of the capitulum, the animal's body is suspended to the scuta in a more transverse direction than is usual. The prosoma is well-developed, and is distinctly separated from the three posterior thoracic segments, by a band of thin membrane. The tunic of the basal part of the sack, where it enters the peduncle in a blunt point, is thickened and covered with roughened rounded papillae. The corium of the sack under the valves, is coloured (after spirits) so dark a brown as to be nearly black; the cirri and trophi are similar, but with a tinge of greenish-purple.

_Filamentary Appendages._--Of these there were, on the prosoma of one specimen, twelve pairs, and in another specimen fourteen pairs, seated in two approximate rows; the middle filaments are the longest, equalling about half the diameter of the thorax: each is flattened, and tapers but little towards its summit, which is roughened with microscopical crests serrated on both sides; on the summit, also, there are a few bristles and some very short, thick, minute spines. These appendages are directed rather towards each other, and towards the thorax. I do not doubt that their numbers vary according to the size of the specimen. I believe that they are occupied by testes. Outside these filaments, on each side of the prosoma, there are two very irregular rows of papillae, intermediate in length between the filaments and the rounded swellings at the bottom of the sack. Beneath the basal articulation of the first cirrus, there is on each side, a short appendage, with a few bristles on its summit.

Lastly, on each side of the middle of the mouth, on the prosoma, there is a longer appendage, dark-coloured, furnished with a few scattered bristles on its sides and apex, and directed upwards and a little towards the adductor scutorum muscle.

_Mouth._--Labrum highly bullate, but with the uppermost part not more bullate than the lower part, and therefore not overhanging it; basal margin much produced; crest with some small blunt teeth and some bristles. The inner fold of the labrum is much thickened, yellow, punctured, and with a tuft of fine bristles on each side.

_Palpi_, approaching each other but not touching, club-shaped, or with broad and square extremities, thickly fringed with serrated bristles.

_Mandibles_ with three unusually strong teeth, slightly graduated in size, with the inferior angle very coa.r.s.ely pectinated; the lower edges of the main teeth are roughened.

_Maxillae_, (Pl. X. fig. 13). Spinose edge about half the length of the mandibles; the two upper spines are unusually strong; close under, and almost hidden by them, there is a tuft of fine spines; in the middle there is a second similar tuft mounted on a prominence; and at the inferior angle there is a third tuft, also mounted on a rather wider prominence, not quite accurately figured. In the inters.p.a.ces between these tufts there are three or four pairs of spines of the usual appearance and projecting just beyond the fine tufts; the upper of the two inters.p.a.ces is rather narrower, but rather deeper, than the lower inters.p.a.ce. Apodeme very long, irregularly shaped, like an =S=, with a remarkable elbow near its attachment; apex slightly enlarged, thin and rounded.

_Outer Maxillae._--On the inner margin there is a deep and conspicuous notch, above and beneath which, there is a compact row of serrated bristles; exteriorly the bristles are rather longer.

_Olfactory Orifices_ very prominent, pointing obliquely towards each other.

_Cirri._--Posterior cirri moderately long, much curled, with the segments (Pl. X, fig. 27) flattened and wide; the anterior surface hemispherically protuberant, supporting six pairs of spines, of which the lower ones approach each other; between these spines there is a large tuft of very fine spines, of which the central ones are the longest; there is an upper lateral group of very short strong spines; dorsal tufts composed of short, fine numerous spines. _First pair_ seated close to the second pair, short, having in both rami eight segments, whereas in the same individual the second pair, which is nearly twice as long, had thirteen, and the sixth pair eighteen segments. Rami of the first pair nearly equal in length, with their segments, excepting the two upper ones, thickly paved with bristles, in the midst of which a tuft of fine spines, as in the posterior cirri, may be distinguished; the dorsal tufts encircle the whole of each segment; the spine-bearing anterior surfaces are protuberant chiefly in the upper part, so that they are oblique. The posterior (?) ramus has its segments much wider than those on the other ramus; and amongst the common spines, in the third and fourth segments, (counting from the bottom,) there are some very strong spines with their upper ends coa.r.s.ely and doubly pectinated, each tooth being upwardly bent into a rectangular elbow. In the fifth segment, some of the spines are doubly pectinated with simple teeth; and most of the spines are doubly serrated. The _Second_ (Pl. X, fig. 25) and _Third cirri_ have the five basal segments (5/13ths of the whole number in the second cirrus, and 5/14ths in the third cirrus) of their anterior rami, extremely broad, protuberant, and paved with serrated bristles, amongst which, (except on the actual lowest segment,) there are some simply pectinated spines, and others with their teeth elbowed, exactly as in the first cirrus. The basal segments of the posterior rami of the second and third cirri, differ from the three posterior cirri only in the spines being slightly more numerous; but none of them are pectinated.

_Pedicels_, rather short; the upper segment resembles, in the arrangement of its spines, the segments of the posterior cirri; the lower segment is longer than the upper, and has _two_ tufts of fine spines, between the two rows of long spines. In the second and third cirri, these two intermediate tufts on the lower segment of the pedicel, are not so distinctly separated from each other.

_Caudal Appendages_, very small, uniarticulate, blunt and rounded; tips bearing a few, very short, thick spines.

_Alimentary Ca.n.a.l._--OEsophagus, somewhat curved at the lower end, where it enters the stomach, which has no caeca; r.e.c.t.u.m, unusually short, extending from the a.n.u.s only to the base of the fifth pair of cirri.

Within the stomach, from top to bottom, there were thousands of a bivalve entomostracous crustacean.

_Generative System._--Both ovaria and testes are largely developed; the former fill the long peduncle; the testes enter both the pedicels of the cirri, and the filamentary appendages on the prosoma; vesiculae seminales very large, reflected at their ends, extending across each side of the stomach. p.e.n.i.s rather small, coloured purplish, with numerous little tufts of bristles.

_Variation._--In some specimens in the British Museum, collected by Sir 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 encas.e.m.e.nt. 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 s.h.i.+elds, 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 h.o.r.n.y, 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 laminae, 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 s.h.i.+eld 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 s.h.i.+elds 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 b.a.l.l.s of calcareous matter, appearing to me as if calcareous matter had been morbidly excreted, and not like a provision for the future.