Chapter L: ANSERIFERA. Linnæus. Syst. Naturæ, 1767 (1)

ANATIFA STRIATA. _Brug._ Encyclop. Meth. (des vers), Pl. clxvi,
fig. 3.

PENTALASMIS DILATATA! (young). _Leach._ Tuckey’s Congo Expedit.,
p. 413, 1818.

ANATIFA SESSILIS (?). _Quoy et Gaimard._ Voyage de l’Astrolabe,
Pl. xciii, fig. 11.

LEPAS NAUTA.[27] _Macgillivray._ Edin. New Phil. Journ., vol.
xxxviii, p. 300.

PENTALASMIS ANSERIFERUS. _Brown._ Illust. Conch., 1844, Pl. li,
fig. 1.

[27] Professor Macgillivray does not consider the species, which
he has described under _L. nauta_, and which I cannot doubt is
the same with the present species, as the _L. anserifera_ of
Linnæus; but I find it so named in all old collections, and it
seems to agree very well with Linnæus’s description. There has
been much groundless confusion about this species; I have no
hesitation in giving _A. striata_, of Brugière, as a synonym,
though I have received from Paris the _Lepas pectinata_ of this
volume, named as the _A. striata_; and on the other hand, Poli
has incorrectly called a common variety of _L. pectinata_ by the
name of _L. anserifera_.

_L. valvis approximatis leviter sulcatis (tergis præcipuè); scuto dextro dente forti interno umbonali, lævo aut dente exiguo, aut merâ cristâ instructo; margine occludente arcuato, prominente: pedunculi parte superiore aurantiacâ._

Valves approximate, slightly furrowed, especially the terga; right-hand scutum with a strong internal umbonal tooth; left-hand with a small tooth, or mere ridge; occludent margin arched, protuberant: uppermost part of peduncle orange-coloured.

Filaments five or six on each side.

Var. (_dilatata_, young); valves rather thin, finely furrowed, often strongly pectinated; scuta broad, with the occludent margins much arched, making the space wide between this margin and the ridge connecting the umbo and the apex: carina often barbed.

Common on ships’ bottoms from the Mediterranean, West Indies,
South America, Mauritius, Coast of Africa and the East-Indian
Archipelago. Central Pacific Ocean. China Sea. Chusan. Sydney.
Attached to pumice, various species of fuci, Janthinæ, Spirulæ;
often associated with _L. anatifera_ and _L. Hillii_, and, in a
young state, with _L. fascicularis_.

_General Appearance._--Capitulum more or less elongated relatively to its breadth; in two specimens, with scuta of equal width, one was longer than the other by the whole of the occludent margin of the terga. Valves white, thick, (in young specimens sometimes diaphanous and thin,) closely approximate to each other; surfaces furrowed to a very variable amount. Terga generally more plainly furrowed than the scuta, of which the basal portion is generally less furrowed than the upper part; ridges, often rough, generally much narrower than the furrows: in half-grown specimens (var., _dilatata_ of Leach,) the ridges are frequently denticulated, and there is even sometimes a row of bead-like teeth along the basal margins of the scuta. The ridges vary much, sometimes alternately wide and narrow; in two specimens of equal size, there were, in one, thirty-two ridges, and in the other only eighteen, on the scutum.

_Scuta_, with the occludent margin rounded and protuberant to a variable degree, but always leaving a rather wide space between the margin, and the ridge which runs from the umbo to the apex; apex pointed. Right-hand internal tooth considerably larger than that on the left, which is often reduced to a mere ridge; internal basal rim thick, sometimes furrowed along its upper edge, but of variable thickness, sometimes not extending as far as the baso-carinal angle. _Terga_, sometimes equalling, sometimes only two-thirds of, the length of the scuta; in young specimens, the two occludent margins form a right-angle with each other; in older specimens they form less than a right-angle, and hence the portion of valve thus bounded is unusually protuberant. _Carina_, within deeply concave; exterior sides finely furrowed longitudinally, generally denticulated; valve only slightly narrowed in above the fork, of which the prongs diverge at an angle of 90°, or rather more, and are wider than the widest upper part of the valve; rim between the prongs reflexed; the heel or external angle, just above the fork, sometimes considerably prominent. I have seen only a single large specimen with its carina barbed. In half-grown specimens, (var. _dilatata_, Leach,) the carina is often strongly barbed, with the upper point much acuminated, the fork about twice as wide as the widest upper part, and the prongs diverging at rather more than a right-angle. In some specimens, especially very young ones, there are at the base of the carina, above the fork, some strong, downward-pointed, inwardly-hooked, calcareous teeth; such occur also in some specimens along the basal margins of the scuta, two of these hooked teeth under the umbones of the scuta being larger than the rest: specimens conspicuously thus characterised came from the Navigator Islands; in these, I may add, the acutely triangular primordial valves were quite plain.

_Peduncle_, generally about as long as the capitulum; in young specimens generally short.

_Filamentary Appendages_, generally five, sometimes six, on each side; one is seated on the side of the prosoma, and the four others placed in pairs beneath the basal articulation of the first cirrus; the lowest posterior filament of the four generally is the largest. In young specimens, having a capitulum only half an inch long, the upper pair of the four often is not developed, or is represented by mere knobs. The mouth presents no distinctive characters. _Cirri_, with the longer ramus of the first pair almost equal to the shorter arms of the second pair; spine-bearing surfaces only slightly protuberant. Caudal appendages smooth, curved, pointed.

_Size._--The largest specimen which I have seen, had a capitulum one inch and a half in length.

_Colours._--The white valves are edged with bright orange membrane; and are so close to each other that no interspaces, coloured from the underlying corium, are left. Peduncle, dark orange-brown, with the uppermost part under the capitulum bright orange all round; the chitine membrane itself being thus coloured. Sack, internally, dark purplish lead-colour. Body and cirri, either nearly white or pale purplish-lead colour, with the arms of the second, third, and fourth cirri, and pedicels of the fifth and sixth, more or less tinted with orange. A specimen preserved during fourteen months in good spirits had only a tinge of orange left round the orifice and round the upper part of peduncle, and on the cirri. In some other specimens, badly preserved, the chitine membrane was quite colourless, and sack and cirri dirty lead-colour. Fresh ova, peach-blossom-red; immature ova, in ovarian tubes, pale pink.

_Monstrous Variety._--In Mr. Stutchbury’s collection, there was a specimen, with the scuta, broad, smooth, thin, and fragile, without any ridge running from the umbo to the apex, and with the occludent margin reflexed. This seemed caused by the shell having been attacked by some boring animal, and from having supported Balani. In the same specimen the first cirrus on one side was monstrously thick and curled; the second cirrus had its posterior ramus in a rudimentary condition. In Mr. Cuming’s Collection, there are small specimens with the zones of growth overlapping each other, with thick irregular margins, and with the carina distorted.

This species has cost me much trouble: I have examined vast numbers of specimens, from a tenth to half an inch in length, attached to light floating objects, such as Janthinæ and Spirulæ from the tropical oceans, which all resembled each other, and slightly differed from the common appearance of _L. anserifera_: this variety is the _Pentalasmis dilatata_ of Leach; and for a long time I considered it as a distinct species. It differs from _L. anserifera_, in the less thickness of the valves, in their being more finely and yet plainly furrowed; in the greater width of the scuta; and more especially, of that part of the valve lying between the occludent margin, and the ridge running from the umbo to the apex; in the less elongation of the area in the terga, bounded by the two occludent margins; and, lastly, in the less size of the whole individual. The trophi and cirri are absolutely identical. Lately, however, in carefully going over a great suite of specimens, all the above few distinctive characters broke down and insensibly graduated away; and I am convinced that this form is only a variety of _L. anserifera_; its different aspect being caused partly by youth, but chiefly, I suspect, from being attached to light objects floating close to the surface of the sea.

The _Lepas anserifera_ can be distinguished by the slight furrows on its valves from all the other species, excepting _L. pectinata_: this latter species can be readily known, by the close proximity in the scuta of the occludent margin, and the ridge extending from the umbo to the apex; by its carina being very narrow above the fork; by the prongs of the fork diverging at an angle of from 135° to 180°; by the thinness of its valves; by the coarseness of the furrows on them; and lastly, by there being at most in _L. pectinata_ only one filamentary appendage beneath the first cirrus.

4. LEPAS PECTINATA. Pl. I, fig. 3.

LEPAS PECTINATA. _Spengler._ Skrifter Naturhist. Selbskabet, 2,
B. 2, H., 1793, Tab. X, fig. 2.

---- MURICATA (var.) _Poli._ Test. Utriusque Scicil., vol. i, Pl.
vi, figs. 23, 29, 1795.

LEPAS ANSERIFERA. _Poli._ Test. Utriusque Scicil., vol. i, Pl. vi,
figs. 25-27.

---- SULCATA. _Montagu._ Test. Brit., Pl. i, fig. 6, 1803.

PENTALASMIS SULCATA. _Leach._ Encyclop. Brit. Suppl., tom. iii,
Pl. lvii, 1824.

---- spirulæ (!) (var.) _Leach._ Tuckey’s Congo Expedit. Appendix,
1818.

---- RADULA (var.) et SULCATUS. _Brown._ Illust. of Conchology,
Pl. li, figs. 3-6, 1844.

---- INVERSUS. _Chenu._ Illust. Conchy., Pl. i, fig. 14.

ANATIFA SULCATA. _Quoy et Gaimard._ Voyage de l’Astrolabe, Pl.
xciii, figs. 18, 20.[28]

[28] I may add, that I have received many specimens incorrectly
labelled _A. striata_, which is properly a synonym of _L.
anserifera_.

_L. valvis tenuibus, crassè sulcatis, sæpe pectinatis; scutorum cristâ prominente ab umbone ad apicem juxta marginem occludentem pertinente: furcæ carinalis cruribus inter angulos 135° et 180° divergentibus._

Valves thin, coarsely furrowed, often pectinated. Scuta with a prominent ridge extending, from the umbo to the apex, close to the occludent margin; fork of the carina with the prongs diverging at an angle of from 135° to 180°.

Filaments absent, or only one on each side.

Var. (Pl. I, fig. 3 _a_), upper part of the terga (bounded by the two occludent margins) produced and sharp; surface of all the valves often coarsely pectinated, and with the carina barbed.

Atlantic Ocean, from the North of Ireland to off Cape Horn;
common, under the tropics; Mediterranean: attached to wood,
cork, charcoal, sea-weed, a reed-like leaf, spirulæ, cuttle-fish
bones, to a bottle together with _L. anatifera_; to a ship’s
bottom, Belfast, (W. Thompson.) Often associated with _L.
fascicularis_. Montagu states (‘Test. Brit.,’ p. 18) that this
species is sometimes attached to the fixed _Gorgonia flabellum_.

_General Appearance._--The capitulum varies considerably in length compared to its breadth, caused chiefly by the greater or less production of the occludent portion of the terga; valves thin, brittle; the furrowed surface varies much in character, narrow and broad ridges often alternating; frequently each ridge (but more especially the ridge running from the umbo to the apex of each scutum, and sometimes that alone,) is covered with prominent, curled, flat, calcareous spines, giving the shell an appearance like that of many mollusca. Other specimens show no trace of these calcified projections. From the thinness of the valves and the depth of the furrows, the margins of the valves are sinuous. _Scuta:_ the ridge running from the umbo to the apex is unusually prominent and curved; it runs very close to the occludent margin, so that, differently from in all the other species, only a very narrow space is left between this margin and the ridge. Internal teeth, under the umbones, either sharp and prominent, or mere knobs; sometimes that on the right side is much larger than that on the left; sometimes they are nearly equal; sometimes that on the left is scarcely distinguishable. Internal basal rim absent, or barely developed.

_Terga:_ these valves have a conspicuous notch to receive the apex of the scuta; the two occludent margins either meet each other at a rectangle, or at a much smaller angle, causing the portion thus bounded to vary much in outline, area, and degree of prominence. This at first led me to think that the _P. spirulæ_ of Leach, in which the point is very sharp and prominent, was a distinct species; but there are so many intermediate forms, that the idea must be given up. I may remark, that in all the species of Lepas, the upper part of the tergum seems particularly variable. The degree of acumination of the basal portion of the tergum also varies; the internal surface sometimes has small crests radiating from the umbo.

_Carina_, broad, within deeply concave; edges sinuous, externally sometimes strongly barbed; narrow above the fork, which latter is wider than the widest upper part of the valve; prongs sharp, thin, diverging at an angle of from 135° to 180°; the rim connecting the prongs not, or only slightly, reflexed.

_Peduncle_, narrow, shorter than the capitulum.

_Filamentary Appendages_, none, or only one, short, obtuse projection on each side, on the posterior face of the swelling under the first cirrus.

_Mouth._--Mandibles, with the inferior point produced into a single pectinated tooth, rarely into two pectinated teeth; on one side of one specimen, there were only four instead of five teeth. Palpi very narrow. Maxillæ highly variable; they may be described as formed of five steps, of which the two lower ones are generally united into a single one, divided by a mere trace of a notch; or with the three lower steps blended into an irregular, projecting surface, and with even the fourth step indistinct. I have seen these two extreme forms on opposite sides of the mouth of the same individual,--on one side the maxillæ being regularly step-form, on the other the whole inferior part forming an almost straight edge, standing high up above the first notch or step which bears the two upper great spines.

_Cirri._--First pair rather far removed from the second pair, with the longer ramus about three-fourths of the length of shorter ramus of second cirrus; spine-bearing surfaces, hardly at all protuberant; lateral marginal spines on the posterior cirri rather long; caudal appendages smooth, rounded, extremely minute: penis very spinose.

_Size._--Capitulum in the largest specimen, six-tenths of an inch long; only a few arrive at this size.

_Colours_, after having been kept in spirits,--sack and cirri, especially first cirrus, clouded with pale purple; peduncle brownish; valves appear blueish in specimens not long preserved, but in specimens kept longer they become perfectly and delicately white.

_General Remarks._--Under the head of _L. anserifera_, I have made some remarks on the diagnostic characters of this species. In the thinness of the valves,--form of the carina, with the rim connecting the prongs being not, or scarcely, reflexed,--and in the shortness and narrowness of the peduncle, there is some approach to _L. australis_, and thence to _L. fascicularis_. In the form of the maxillæ,--in one specimen having the mandible on one side bearing only four teeth,--and in the frequent absence of filamentary appendages, there is some approach to the genus _Pæcilasma_; but there is no such approach in the characters derived from the capitulum. We have seen that, as in so many other species of this genus, most of the parts are variable, and this is the case to a most unusual extent in the form of the maxillæ. Dr. Leach has attached eight specific names to the specimens preserved in the British Museum.

5. LEPAS AUSTRALIS. Pl. I, fig. 5.

_L. valvis glabris, tenuibus, fragilibus; scutorum dentibus umbonalibus utrinque internis; carinæ parte superiore latâ, planâ, suprâ furcam valdè constrictâ; furcæ cruribus latis, planis, tenuibus, acuminatis, intermedio margine non relexo._

Valves smooth, thin, brittle; scuta with internal umbonal teeth on both sides. Carina with the upper part broad, flat; much constricted above the fork, which has wide, flat, thin, pointed prongs, with the intermediate rim not reflexed.

Filaments, two on each side.

Common on Laminariæ in the whole Antarctic Ocean: Bass’s
Straits, Van Diemen’s Land: Bay of Islands, New Zealand, lat.
35° S.: lat. 50° S., 172° W.: coast of Patagonia, lat. 45° S.:
attached to bottom of H. M. S. Beagle, lat. 50° S., Patagonia:
attached to a Nullipora, (I presume a drift piece,) British
Museum.

_General Appearance._--Capitulum rather obtuse and thick; valves thin, brittle, approximate, either white and transparent, or dirty-brown and opaque; or sometimes tinted internally with purple (perhaps the effects of being preserved in spirits); surface plainly marked by lines of growth, rarely marked with traces of lines radiating from the umbones. _Scuta_ with teeth on both sides, nearly equal; internal basal rim rather wide, sometimes furrowed; basal margin considerably curved inwards. _Terga_ rather wide; basal angle blunt; angle formed by the two occludent margins blunt and rounded. _Carina_ (fig. 5 _a_) with the apex blunt, flat; the middle part generally very broad; much constricted above the fork, where it is internally deeply concave, and externally carinated; fork twice as broad as the broadest upper part of the valve; with the prongs flat, broad, thin, pointed, diverging at about an angle of 75°, with the intermediate rim not at all reflexed; the fork generally not deeply imbedded in the chitine membrane of the peduncle, so as to be quite easily visible externally; sometimes there is an internal, transverse, depressed line on the fork. In young specimens, with the capitulum about a quarter of an inch long, the fork of the carina is not developed, the lower slightly inflected portion consisting simply of an oval plate, twice as wide as the upper part. Until I had carefully examined a perfect series, showing the gradual changes in this part, I did not doubt that the young specimens formed a distinct species, and named it accordingly: the shortness of the penis first made me perceive that the specimens were immature. At this early age, I may add, the filamentary appendages were not developed. _Peduncle_ either quite short, or as long as the capitulum, close under which it is considerably constricted all round.

_Filamentary Appendages._--Two on each side; one long, tapering, placed on the prosoma (in one specimen represented by a mere knob), and the second shorter, situated on the posterior margin of the swelling beneath the first cirrus.

_Mouth._--Maxillæ, with three large spines at the upper angle, and with the first step distinct, but narrow; mandibles with five teeth; in young specimens the inferior point ends in a single spine; sides of the supra-oral cavity very hairy; the membrane, forming the inner fold of the labrum, yellow and thickened in the form of a spoon.

_Cirri._--In the posterior cirri there are, at the upper lateral edges of the segments on _both_ sides, small spines; the segments in the first cirrus, and in the broad anterior ramus of the second cirrus, are hemispherically and considerably protuberant. Caudal appendages smooth.

_Size._--The largest specimen had a capitulum one inch long.

The _Colours_ (after having been long in spirit) of the valves have already been given; sack and peduncle dirty yellowish-brown, with the parts corresponding to the margins of the valves much darker brown, or almost black; segments of the cirri clouded with dark brown; body and pedicels of the cirri dirty yellowish. I have reason to believe that the colours are totally different in living specimens.

_Monstrous Varieties._--Most of the specimens from lat. 50° S., on the coast of Patagonia, were more or less deformed, with the successive zones of growth overlapping each other, and forming coarse concentric ridges. The carina in several specimens was laterally distorted.

I have already remarked that this species has some affinity to _L. pectinata_; but it is much more closely related to _L. fascicularis_, the affinity being clearly shown by the thinness and translucency of the valves, their convexity, by the width and little acumination of the upper part of the carina, by the width of the fork, and by its not being deeply imbedded. In young specimens, moreover, before the fork is fully developed, there is a remarkable similarity between the two species, in the form of this lower part of the carina. Again, the narrowness and inflection of the peduncle under the capitulum in _L. australis_, and lastly, the lateral marginal spines on both sides of the segments of the posterior cirri, all clearly indicate this same affinity to _L. fascicularis_.

I believe this species is confined to the southern ocean; and perhaps there represents _L. fascicularis_ of the northern and tropical seas. It must, judging from the number of specimens brought home by Captain Sir J. Ross, and from those previously in the British Museum, and from those collected by myself, be a very common species.

6. LEPAS FASCICULARIS. Pl. I, fig. 6.

LEPAS FASCICULARIS. _Ellis_ and _Solander_. Zoophytes, 1786, Tab.
xv, fig. 5.

---- ---- _Montagu._ Test. Brit. Suppl., 1808, pp. 5, 164.

---- CYGNEA. _Spengler._ Skrifter Naturhist. Selbskabet, Bd. i,
1790, Tab. vi, fig. 8.

---- DILATA. _Donovan._ British Shells, 1804.

PENTALASMIS FASCICULARIS. _Brown._ Illust. Conch., 1844, Pl. li,
fig. 2.

---- SPIRULICOLA (!) et DONOVANI (!) _Leach._ Tuckey’s Congo
Expedit., p. 413, 1818.

ANATIFA VITREA. _Lamarck._ Animaux sans Vertebres.

DOSIMA FASCICULARIS. (!) _J. E. Gray._ Annals of Philosophy, vol.
x, 1825.

PENTALEPAS VITREA. _Lesson._ Voyage de la Coquille. Mollusca, Pl.
xvi, fig. 7, 1830.

ANATIFA OCEANICA (!) _Quoy_ et _Gaimard_. Voyage de l’Astrolabe,
Pl. xciii.

_L. valvis glabris, tenuibus, pellucidis; carinâ rectangulè flexâ, parte inferiore in discum planum oblongum expansâ._

Valves smooth, thin, transparent; carina rectangularly bent, with the lower part expanded into a flat oblong disc.

Filaments, five on each side; segments of the three posterior cirri with triangular brushes of spines.

Var. (_Donovani_, of Leach.) Carina with the upper part flat, spear-shaped, externally with a narrow central ridge.

Var. (_Villosa._ Pl. I, figs. 6 _b_, _c_.) Valves placed rather distant from each other; carina extremely narrow, with the upper part of nearly the same width throughout; terga with the lower part much acuminated; body of animal finely villose.

Coasts of Great Britain and France; Baltic Sea, according to
Montagu Southern United States (from Agassiz); tropical Atlantic
Ocean; East-Indian Archipelago, off Borneo and Celebes; Pacific
Ocean, between the Sandwich and Mariana Archipelagos; New
Zealand: attached to fuci, Spirulæ Janthinæ, Velellas, often to
feathers and cork; often associated with the young of _L.
anserifera_, (var. _dilatata_,) and _L. pectinata_.

_General Appearance._--Capitulum highly variable in all its characters; thick and broad in proportion to its length, but the breadth is variable,--in some specimens, the capitulum being longer by one-fifth of its total length than broad; in others, one-fifth broader than long. Valves generally approximate; in some varieties, however, from the narrowness of the carina and terga, the valves stand far apart, there being an interval between the carina and scuta of nearly half the breadth of the latter. Valves excessively thin, brittle, transparent, colourless, smooth, but generally sinuous along the zones of growth, which are conspicuous: valves generally covered throughout by thin chitine membrane, which is thickly clothed, especially in the interspaces between the valves, with minute spines, barely visible to the naked eye. _Scuta_ with the lower part of the tergo-carinal margin extremely protuberant; occludent margin, more or less, but slightly reflexed, with a depressed line running from the umbo to the apex; basal margin much reflexed, but to a variable extent and at a varying angle, even up to a right angle,--an external rim or collar being thus formed. There are no distinct _internal_ teeth, but the basal margin under the umbones, is more or less distinctly produced into a rounded disc or projection, which is generally not so much outwardly reflexed as the rest of the basal margin: there is no distinct internal basal rim. The primordial valves are generally visible, but they do not lie, as in all other species, close to the basal margin, but a little above it,--the lower reflexed portion having been subsequently developed. _Terga_ flat, with the occludent margin slightly arched, and not, as in the foregoing species, formed of two sides; apex bent towards the carina; width of the lower half highly variable, owing to the varying extent to which the scutal margin is hollowed out; in some specimens, the whole lower half beneath the apex of the scuta is of nearly the same width throughout; in other specimens this lower part is spear-shaped. The widest part of the tergum either equals in width, or is only two-thirds of the width of the widest part of the carina beneath its umbo. _Carina_ (Pl. I, fig. 6 _a_) highly variable in shape, with the part above the umbo either spear-shaped and slightly concave within, or nearly flat and furnished with a central external ridge; or the upper part (fig. 6 _c_) is of equal and extreme narrowness throughout, and deeply concave within, appearing as if only the central ridge had been developed. The part below the umbo, (answering to the fork in the foregoing species,) is about one-third of the length of the whole valve, and generally twice as wide as the upper part, but in the variety with the upper part of the carina equally narrow throughout, the lower part is thrice as wide as the upper; the disc, or lower part, is generally slightly concave within, exteriorly either with or without a central ridge; basal margin rounded; lateral margin more or less curved, according to the form of the upper part. The disc is not more deeply imbedded in membrane than is the upper part of the valve. The heel or umbo is either angular and prominent, or rounded. In very young specimens the carina is simply bowed, instead of being rectangularly bent.

_Peduncle_,--short, narrow, being abruptly inflected all round under the basal edges of the capitulum; lower part of very variable shape, being often suddenly contracted into a mere thread (fig. 6 _b_), which sometimes widens again at the extreme end. The external membrane is very thin, and is penetrated by the usual fine tubuli leading to the corium; its surface is wrinkled and destitute of spines, or with extremely few. The peduncle is often completely surrounded by a yellowish ball, (of which I have seen specimens from the coast of England, and from off Borneo,) sometimes half as wide as the capitulum, composed of very tender, vesicular, structureless membrane, and of a pulpy substance: perhaps the yellow colour may be owing to long immersion in spirits. Some authors have supposed that the ball was the ovisac of the animal; and for the first few minutes, deceived by the numerous included spores of, as I believe, Bacillariæ, I thought that this was the case; others have supposed that it consisted of some encrusting algæ or other foreign organism; but it is, in reality, a most singular development of the cement-tissue, which ordinarily serves to attach Cirripedes by their bases to some extraneous object, but here surrounding that object and the peduncle, gives buoyancy, by its vesicular structure, to the whole. The membrane of the ball falls to pieces in caustic potash, differently from the chitine membrane of the enclosed peduncle, and this shows that there is some difference in composition from ordinary cement. The ball, when cut in two, exhibits an obscure concentric structure. The whole is excreted by the two cement-ducts, through two rows of orifices, one on each side of the surrounded portion of the peduncle; and I actually traced, in one case, the yellow pulpy substance coming out of the cement-ducts. The upper apertures are in gradation larger than those below them, and they stand a little further apart from each other; these are figured as seen from the outside, much magnified, at Pl. I, fig. 6 _d_. I did not succeed in finding the cement-glands, but I followed the ducts, of rather large size, running for a considerable distance as usual along and within the longitudinal muscles of the peduncle. Nearly opposite the uppermost aperture, on each side, the duct passes out through the corium, and becomes laterally attached to the outer membrane of the peduncle, at which point an aperture is formed (as in other cases, by some unknown process), thus giving exit to the contents of the duct. Beneath this upper aperture the duct runs down the peduncle, between the corium and the outer membrane, till it comes to the next aperture, to which it is also attached, and so on to all the lower ones; but I believe no cement tissue continues to pass out through these lower apertures. Beneath the lowest aperture the two ducts run into the two prehensile antennæ of the larva, which, as usual, terminate the peduncle. The antennæ are attached to some small foreign body in the centre of the vesicular ball, by the usual tough, light brown, transparent cement. The two upper apertures are nearly on a level with the outside surface of the ball; and it was evident that as the animal grows, new apertures are formed higher and higher up on the sides of the peduncle, and that out of these, fresh vesicular membrane proceeds, and grows over the old ball in a continuous layer. It appears that the growth of the vesicular ball is not regular,--that it is not always formed,--and that when formed the whole, or the lower part, sometimes disintegrates and is washed away. As that portion of the peduncle which is enclosed ceases to grow, and has its muscles absorbed, retaining only the underlying corium, whereas the upper unenclosed portion, and likewise, (as it appears) lower portions once enclosed but since denuded, continue to increase in diameter, the peduncle, when the vesicular ball is removed, often has the most irregular outline, contracting suddenly into a mere thread, and then occasionally expanding again at the basal point.

Frequently two or three specimens have their peduncles imbedded in one common ball, of which there is a fine specimen in the College of Surgeons (Pl. I, fig. 6), the ball being about one inch and a quarter in diameter, with a slice cut off. In this specimen, it is seen that the vesicular membrane proceeding from several individuals, unites to form one more or less symmetrical whole, and that the original common object of attachment is entirely hidden. Dr. Coates[29] gives a curious account of the infinite number of specimens, through which he sailed during several days, in the Southern Atlantic Ocean: the balls appeared like bird’s eggs, and were mistaken for some fucus, which was supposed to have encrusted the scales of the Velellæ, to which the Cirripede had originally become attached. Several individuals had their peduncles imbedded in the same ball, “which floated like a cork on the water.” As this species grows into an unusually bulky animal, we here see a beautiful and unique contrivance, in the cement forming a vesicular membranous mass, serving as a buoy to float the individuals, which, when young and light, were supported on the small objects to which they originally had been cemented in the usual manner.

[29] Journal of the Acad. Nat. Sc., Philadelphia, vol. vi, p.
138, 1829.

_Filamentary Appendages._--Five on each side, of which four lie in pairs at the base of the first cirrus (of these, only three are sometimes developed), and one on the flank of the prosoma.

_Mouth._--Palpi much acuminated. Mandibles with five teeth; the first not far remote from the second; inferior point rather broad and finely pectinated. Maxillæ with two large, unequal, upper spines, and four regular steps.

_Cirri._--Posterior cirri, with the upper parts of the segments slightly protuberant; in young specimens, the spines can be seen to consist of five pairs, placed in two converging lines in the upper half of each segment, with numerous minute, latero-marginal, and intermediate little bristles: in large specimens, all these latter have so increased in number, that the normal five pair cannot be distinguished, and the front of each segment is covered by a triangular thick brush of bristles, all pointing in the same direction, thus giving a very unusual character to the posterior cirri: the dorsal tuft on each segment consists of six or seven large spines, with from one to three dozen fine ones. First cirrus and anterior ramus of second cirrus with broad brushes of bristles. The pedicels of all the cirri are thickly covered with bristles. _Caudal_ appendages smooth, with rounded summits.

_Penis_ very hairy: vesiculæ seminales purple, much convoluted, lying within the prosoma; testes dendritic, scarcely enlarged at their terminal points, purplish; ovigerous fræna large with sinuous margins, the glandular beads being arranged in groups.

_Size._--The largest specimen (from the coast of Devonshire) had a capitulum 1.6 of an inch long, and 1.2 broad, and of unusual thickness.

_Colours_, after having been in spirits: front surfaces of the segments of the cirri and of the pedicels purple. In some specimens from off Borneo, parts of the sack and the interspaces between the two scuta, were of a fine purple. Montagu states, that the whole shell and body of animal, when fresh, are pale blue, with the cirri spotted with brown.

_General Remarks._--The extreme variability of this species is remarkable. In the College of Surgeons, there is a group of specimens collected by Mr. Bennett, I believe, in the Atlantic, in which the extreme narrowness of the carina and of the terga (Pl. I, fig. 6, _b_, _c_) (with consequent wide spaces of membrane left between these valves), led me, at first, to entertain no doubt, that it was quite a distinct species, which was strengthened by finding that the whole surface of the cirri were villose, with very minute spines; hence I called this variety, _villosa_. On the closest examination, however, I could detect no other differences, and the narrowness of the carina and terga varied very considerably: moreover, in one of the specimens, which was about intermediate in the form of its valves between this variety and the common form, the surfaces of the cirri were not in the least degree villose. Again, in some other specimens, the terga were as narrow as in Mr. Bennett’s, whilst the carina had its usual outline.

In a var. (called by Leach, _P. Donovani_,) from the Atlantic, under the Equator, the carina is remarkable from the extreme flatness of the upper part, and from the presence of an exterior, narrow, central ridge. In one specimen from Jersey, in the British Museum, the carina made an extremely near approach to this same form.

_Affinities._--This species is certainly much the most distinct of any in the genus, and Mr. Gray has proposed to separate it under the name of Dosima; but considering the close similarity of the whole organisation of the internal parts, together with the transitional characters afforded by _L. australis_, I think the grounds for this separation are not quite sufficient. I have remarked, under _L. australis_, on the affinity between that and the present species. In the carina terminating in a disc (though here not imbedded), there is some slight affinity to _Pæcilasma eburnea_ and _crassa_, and markedly so in the arrangement of the bristles on the posterior cirri. In the valves being covered with villose membrane, and to a certain extent in the form of the carina and of the occludent margin of the terga, and especially in the two rows of cement-orifices in the peduncle, there is some affinity to Scalpellum.

PÆCILASMA. _Nov. Genus._[30] Plate II.

ANATIFA. _J. E. Gray._ Proc. Zoolog. Soc., 1848, p. 44.

TRILASMIS. _Hinds._ Voyage of the Sulphur. Mollusca, 1844.

[30] [Greek: Pokilos], various, and [Greek: elasma], plate or
valve. I have not been able to adopt Mr. Hinds’ name for this
genus, as it would be too glaringly incorrect to call a
five-valved species, a _Trilasmis_.

_Valvæ, 3, 5, aut 7, approximatæ: carina solùm ad basales apices tergorum extensa, termino basali aut truncato aut in discum profunde infossum producto: scuta pænè ovalia, umbonibus ad angulum rostralem positis._

Valves, 3, 5, or 7, approximate: carina extending only to the basal points of the terga; with its lower end either truncated or produced into a deeply imbedded disc. Scuta nearly oval, with their umbones at the rostral angle.

Mandibles with four teeth; maxillæ notched, with the lower part of edge prominent; anterior ramus of the second cirrus not thicker than the posterior ramus; caudal appendages uniarticulate, spinose.

Generally attached to Crustacea.

I have already given my reasons for instituting and separating this genus from Lepas; as far as the capitulum is concerned, the differences between these genera certainly appear trivial; they consist in the carina not extending up between the terga, and in the lower end being either truncated, or produced into an imbedded disc: the terga have a single occludent margin. The included animal’s body differs in more important respects; for both mandibles and maxillæ are very distinct; the cirri of some of the species also differ; and the caudal appendages are here always spinose: there are no filamentary appendages: and lastly, the habits are different.

The genus may be divided into two sections, firstly, _P. Kæmpferi_ and _P. aurantia_, which have their carinæ basally truncated, the basal angles of their terga cut off, and the anterior rami of their second cirri shorter than the posterior rami; and, secondly, _P. crassa_, _P. fissa_, and _P. eburnea_, which in these several respects are otherwise characterised. The _P. eburnea_, however, differs rather more from _P. crassa_ and _P. fissa_, than these two do from each other; but certainly not enough to allow of the retention of Mr. Hinds’ genus of Trilasmis. _P. crassa_, in an especial degree, connects together all the forms.

_General Appearance._--Capitulum oval, more or less produced, flat or gibbous; formed of three, five, or seven approximate valves; the lesser number arising from the abortion of the terga, and the greater number from the scuta being divided into two segments. Valves moderately thick, either white or reddish, smooth or striated, and sometimes partly covered by membrane, bearing minute spines. _Scuta_ oval, of varying proportions; the basal margin is generally narrow, and blends into the carina-tergal margin; the internal basal rim generally is well developed, sometimes with, and sometimes without internal teeth beneath the umbones. In _P. eburnea_, and sometimes in _P. crassa_, there is a line of apparent fissure, and in _P. fissa_ of actual disseverment, running from the umbo to the apex of each scutum, nearly in the line in which a ridge extends in Lepas: the primordial valves of the scuta in these three species, are seated at the basal angles of the lateral and larger segments. The positions of the primordial valves, and the direction of growth in the calcified valves, are, in all the species, the same as in Lepas. In several of the species attached to Crustacea, the two scuta are unequally convex, which is caused, as was pointed out to me by Mr. Gray, by that valve which lies close and nearly parallel to the body of the crab, being least developed. The _Terga_ are either quite absent, or rudimentary as in _P. crassa_, or pretty well developed as in the other species: the occludent margin is single, and not double as generally in Lepas; the basal angle is either pointed or truncated. The _Carina_ varies considerably in shape, but never extends up between the terga, nor ends downwards in a fork; in the first two species it is truncated; in the others, it terminates in a deeply-imbedded oblong disc, which in _P. eburnea_ seems almost entirely (but of course not quite) to separate the inside of the capitulum from the peduncle; a similar separation is effected in _P. fissa_, where the imbedded disc is small, by two large teeth on the internal basal rims of the two scuta. The carina is always narrow, and either solid internally or very slightly concave.

_Peduncle_, is very short and narrow; the membrane is generally ringed with thicker, yellower portions, and often bears very minute spines.

_Size._--All the species are small, with a capitulum not exceeding half an inch in length.

_Filamentary Appendages._--None.

_Mouth._--Labrum generally considerably bullate in the upper part, with a row of teeth on the crest. The _mandibles_ have four teeth, with the inferior point narrow and spine-like, or rudimentary and absent. The _maxillæ_ have, under the two or three upper great spines, a deep notch itself bearing spines; beneath this, the lower part is straight and considerably prominent, Pl. X, fig. 15. Outer maxillæ are covered on their inner sides continuously with spines.

_Cirri._--The first pair is sometimes seated very distant from the second. The arrangement of the spines on the posterior cirri varies, to an unusual degree within the limits of the same genus. We have either the ordinary structure of anterior pairs, with single fine intermediate spines (as in _P. Kæmpferi_ and _aurantia_), or we have the pairs increased by one or two additional longitudinal lateral rows, as in _P. eburnea_; or we have the front spines forming a single transverse row, as in _P. crassa_ and _P. fissa_, Pl. X, fig. 29, _a_. The segments in none of the species are protuberant; the anterior ramus of the second cirrus does not seem to be thicker than the posterior ramus, as is usually the case. The rami of the second, and of most of the other cirri, are unequal in length,--the anterior ramus, contrary to the ordinary rule, being longer in _P. eburnea_, _P. fissa_, and _P. crassa_, than the posterior ramus by several segments; I have hitherto observed this inequality only in the sessile genus Chthamalus.

The _Caudal Appendages_ are small, uniarticulate, and always furnished with bristles.

_Distribution._--Four out of the five species live attached to
Crustacea in the European and Eastern warmer temperate and
tropical oceans; the fifth species was found attached to the
dead spines of an Echinus, off New Guinea. It is probable that
several more species will be hereafter discovered.

1. PÆCILASMA KÆMPFERI. Pl. II, Fig. 1.

_P. valvis 5; carinæ basi truncatâ et cristatâ: scutorum dentibus internis umbonalibus fortibus: tergorum acumine basali truncato, margini occludenti pæne parallelo._

Valves 5; carina with a truncated and crested base; scuta with strong internal umbonal teeth; terga with the basal point truncated, almost parallel to the occludent margin.

Maxillæ with short thick spines in the notch under the two upper great spines; caudal appendages with scattered bristles on their summits, and along their whole outer margins.

Japan; attached, in great numbers, to the upper and under sides
of the _Inachus Kæmpferi_ of De Haan, a slow-moving brachyourous
crab, probably from deep water. British Museum.

_General Appearance._--Capitulum rather compressed, narrow, and produced. Valves white, tinged with orange, smooth, moderately thin, occasionally with faint traces of striæ radiating from the umbones. _Scuta_, apex pointed, with a very slight ridge running to the umbo; basal margin equalling two thirds of the length of the terga, with an internal basal rim; on the under side of each valve, beneath the umbo, there is a strong tooth. Out of the numerous specimens, all excepting one had their scuta unequally convex, with their occludent margins unequally curved, that of the more convex valve at the umbo, curling beyond the medial line. The basal end of the carina is, likewise, slightly curved laterally, and always turns towards the more convex valve. This inequality, as Mr. Gray pointed out to me, depends on the position of the specimens; the flatter side lying close to the carapace of the crab. _Terga_, flat, oblong, nearly rectangular; occludent margin straight; basal angle, truncated, almost parallel to the occludent margin; in width, three or four times as wide as the carina. _Carina_, (fig. 1, _a_) short, narrow, slightly curved, upper part broadest, with the apex rounded, only just passing up between the basal broad ends of the terga; externally carinated, internally very slightly concave; basal end abruptly truncated, crested, not deeply imbedded in the membrane of the peduncle.

_Peduncle_, barely as long as the capitulum, apparently (for specimens dry and much shrunk) narrow, surrounded by rings or folds of thicker yellowish membrane, of which the upper ones retain moderately long spines; low down these rings become confluent; whole surface finely dotted, dots largest on the rings.

_Mouth._--Labrum highly bullate in the upper part, with a row of teeth on the crest; mandibles with four teeth, the fourth close to the inferior apex, which is very little developed, sometimes making the fourth tooth appear simply bifid. Maxillæ with two large spines on the upper angle, beneath which there is a large depression, bearing one rather long and thick, and four short and thick, spines; inferior upraised part with a double row of longer and thinner spines.

_Cirri._--Posterior cirri with segments bearing five pairs of spines, of which the lowest pair is very minute; intermediate spines minute; spines of the dorsal tuft thin, of nearly equal size; segments not at all protuberant, elongated. First cirrus, standing far separated from the second (as in Scalpellum), with its nearly equal rami rather above half as long as those of the second cirrus. Second cirrus with anterior ramus not thicker, and scarcely more thickly clothed with spines, than the posterior ramus, but shorter than it by three or four segments; the spines not forming a very thick brush on the anterior ramus. Both rami of third cirrus with a longitudinal row of minute spines, parallel to the main pairs. Between the bases of the pedicels of the first pair of cirri, there are two closely approximate, conical flattened protuberances, like the single one to be described in Ibla.

_Caudal Appendages_, about one third of the length of the pedicel of the sixth cirrus, with some moderately long and strong spines at the end, and down the whole outer sides.

_Ova_, much pointed. _Penis_, hairy.

_Size._--Capitulum in largest specimens half an inch long.

2. PÆCILASMA AURANTIA. Pl. II, Fig. 2.

_P. valvis 5; carinæ basi truncatâ: scutis ovatis, margine basali perbrevi, dentibus parvis, internis, umbonalibus instructo: tergorum acumine basali perobliquè truncato._

Valves 5; carina with a truncated base; scuta oval, with the basal margin very short, furnished with small internal umbonal teeth; terga, with the basal point very obliquely truncated.

Maxillæ with fine spines in the notch under the three great upper spines; caudal appendages with scattered bristles on their summits, and along only the upper part of their outer margins.

Madeira; found by the Rev. R. T. Lowe, attached to the rare
_Homola Cuvierii_, probably a deep-water crab. British Museum.

_General Appearance._--This species so closely resembles _P. Kæmpferi_, that it is superfluous to describe it in detail; and I will indicate only the points of difference. When the valves have been well preserved, they are of fine pale orange colour, and hence the name above given, which was proposed by the Rev. R. T. Lowe.

_Scuta_, with the internal umbonal teeth small; basal internal marginal rim very prominent, furrowed within; basal margin short, (only equalling half the length of terga), owing to the great curvature of the lower part of the carino-tergal margin; hence, the outline of the scuta is almost pointed oval. I saw no appearance of inequality in the two sides.

_Terga_, rather smaller in proportion to the scuta, than in _P. Kæmpferi_, with the basal end very obliquely truncated, so as to appear at first simply pointed, not parallel to the occludent margin; apex considerably more pointed and produced than in the foregoing species.

_Carina_, almost of equal narrowness throughout, barely concave within; lower end triangular, abruptly truncated, and not crested.

_Primordial valves_ very plain, with the usual hexagonal structure: those of the terga, rounded at both ends, instead of being square, as in the mature calcified valves.

_Peduncle_ short, narrow, not half as long as the capitulum; paved with minute equal beads, as in the genus Dichelaspis.

_Mouth._--Mandibles with the fourth tooth very small; inferior angle rudimentary. Maxillæ, with three great upper spines, beneath which there is a deep notch bearing some delicate spines; inferior upraised part, as in _P. Kæmpferi_.

_Cirri._--Rami of first cirrus hardly more than one third as long as the rami of the second cirrus, which latter rami are unequal in length by only two segments; the posterior ramus being the longer one.

_Caudal Appendages_, with only two or three lateral bristles, besides those on the summit.

_Size._--Capitulum, three to four tenths of an inch long.

_General Remarks._--This species has the closest general resemblance to _P. Kæmpferi_, and is evidently a representative of it. On close examination, however, almost every part differs slightly; the chief points being the narrowness of the basal margin of the scuta; the obliqueness of the truncated basal end of the terga and the sharpness of the upper end; the rudimentary state of the inferior angle of the mandibles; the character of the spines on the maxillæ; the proportional lengths of the cirri, and the fewness of the spines on the outer sides of the caudal appendages. The fact of Madeira having this Pæcilasma, a representative both in structure and habits of a Japan species, is interesting, inasmuch, as I am informed by Mr. Lowe, that some of the Madeira fishes are analogues of those of Japan.

3. PÆCILASMA CRASSA. Pl. II. Fig. 3.

ANATIFA CRASSA. _J. E. Gray._ Proc. Zoolog. Soc., 1848, p. 44,
Annulosa, Tab. iii, figs. 5, 6.

_P. valvis 5; carinæ termino basali in discum parvum infossum producto: scutis convexis, dentibus internis umbonalibus nullis: tergis pæne rudimentalibus, vix carinâ latioribus._

Valves 5; carina with the basal end produced into a small imbedded disc; scuta convex, without internal umbonal teeth; terga almost rudimentary, scarcely broader than the carina.

Spines on the segments of the posterior cirri arranged in single transverse rows.

Madeira; attached to the _Homola Cuvierii_, Rev. R. T. Lowe.
British Museum.[31]

_General Appearance._--Capitulum highly bullate, or thick. Valves rather thick, opaque, either pale or dark flesh-red, smooth, yet rather plainly striated from the umbones. There are a few very minute spines on the membranous borders of the valves.

_Scuta_ highly convex, broadly oval, apex broad rounded; basal margin narrow, much curved; no internal, umbonal teeth; basal internal rim strong, running up part of the occludent margin. A slightly prominent ridge, either rounded or angular, but in one specimen a narrow depressed fissure-like line, runs parallel to the occludent margin and ends near the apex in a slight notch; this fact is of interest in relation to the structure of the scuta in _P. eburnea_ and _P. fissa_. The scuta are either equally or very unequally convex; in the latter case, the occludent margin of one valve is curled, so that its umbo is not quite medial.

[31] It is stated, in ‘Zoolog. Proc.,’ (1848, p. 44,) that this
species was attached to a gorgonia, from Madeira; I cannot but
suspect that there has been some confusion with the _Oxynaspis
celata_ from Madeira, which is thus attached.

_Terga_, minute, almost rudimentary, scarcely broader than the carina, and half as long as the chord of its arc; carinal margin slightly curved; scutal margin straight, with a slight prominence fitting into a notch in the scuta; basal end bluntly pointed.

_Carina_, (fig. 3, _a_) rather shorter than the scuta, extending up only to the basal ends of the terga; moderately curved; apex moderately sharp; middle part broadest, externally carinated; internally not concave, with the inner lamina of shell, at the basal end, produced into a very small oblong disc or tooth, which is only as wide as the narrowest upper part of the valve. The exterior keel does not extend on to this disc, which is slightly constricted at its origin.

_Peduncle_ very short, narrow, ringed, and apparently without spines.

_Size._--Capitulum four tenths of an inch long.

The following parts of the animal are described from some small and not well preserved specimens from Madeira, which I owe to the kindness of Mr. Lowe.

_Mouth._--Labrum highly bullate in the upper part, with large, inwardly pointed, unequal teeth. Mandibles, with four large, pointed, equal-sized teeth, with the inferior angle very narrow, acuminated like a single spine. Maxillæ, with three (?) large upper spines, of which the middle one is extremely strong and long, beneath which, there is a deep notch with a single strong spine, and with the whole inferior part square and much upraised, so as to stand on a level almost with the tips of the great upper spines.

_Cirri_ in a miserable state of preservation; first cirrus short, second cirrus with rami unequal, and I suspect the anterior one the longest; some of the other cirri also have unequal rami. The segments of the posterior cirri are not protuberant, they have on their anterior faces a single transverse row of bristles: in the upper segments, some of the spines in each dorsal tuft (which is much spread out), are _much_ thicker, though rather shorter than those on the anterior face. This peculiar structure is common to all five posterior cirri.

_Caudal Appendages._--I can only say that they are spinose on their summits.

_Affinities._--This species is allied to _P. eburnea_ in the rudimentary condition of its terga; in the disc-shaped basal end of its carina; and in the presence in some specimens, of a fissure-like line on the scuta parallel to their occludent margins. Its affinity, however, is closer to _P. fissa_, as is more especially shown by the remarkable arrangement of the spines on the five posterior cirri.

4. PÆCILASMA FISSA. Pl. II, Fig. 4.

_P. valvis 7; scuto utroque è duobus juxtapositis segmentis formato; segmento altero intus dentato: tergis brevibus, ter aut quater carinâ latioribus: carinæ termino basali in discum parvum angustum infossum producto._

Valves 7; each scutum being formed of two closely approximate segments; of which one is internally toothed: terga short, three or four times as wide as the carina: carina with the basal end produced into a small, narrow, imbedded disc.

Spines on the segments of the posterior cirri arranged in single transverse rows.