Chapter XXXIII: Introduction (29)

_Male Organs._--The whole surface of the ovarian sack, the space before it, even to within the lower parts of the mouth, the posterior half of the last thoracic segment, and especially the whole three abdominal segments, are completely netted by branching delicate vessels or ducts terminating in spherical glands about 1/2000th of an inch in diameter. These little glands include a brownish pulpy centre, and sufficiently resemble the testes of other cirripedes in appearance, position, and connecting ducts, to make me believe that such is their nature. I may remark that in the more central parts of the abdomen the glands and ducts seemed to be in process of formation by the confluence of cellular matter, and in some other cirripedes I have suspected that the testes are periodically renewed, or at least redeveloped from an undistinguishable condition. Within the posterior half of the abdomen, some of the ducts become thicker and unite, others joining in laterally, so as together to make a dark chord, 7/2000ths of an inch in diameter. Until dissecting this chord, I thought it was a single vesicula seminalis, but it separated into several rather thick ducts or vesiculæ. I was not able to remove from within them the contained matter, but it appeared very finely and longitudinally flocculent, like spermatozoa not quite matured. In accordance with the immature state of the contents of the ovarian sack, in all probability these ducts would hereafter have become greatly enlarged, and have formed a compound vesicula seminalis of considerable size. The dark chord, formed by their union, contracts as it enters the rudimentary penis, and terminates in a very minute orifice on its apex. The penis consists of a papilla, only 3/4000ths of an inch in length, situated on the extreme point of the abdomen, but rather towards the ventral surface.

_Metamorphosis._--In accordance with the general law of the correlation of parts, it may be inferred, from the description and measurements of the pupal antennæ immediately to be given, that this abnormal creature was developed within a pupa of the same general structure, and of about the size, as the pupæ whence Scalpellum, Alcippe, and many other cirripedes are developed. As the ova are of remarkably small size, indeed I have seen no others quite so small, it is certain that the larvæ, as in the case with all other cirripedes, excepting Cryptophialus, must undergo several metamorphoses, and increase much in size, before attaining their pupal condition.

_Attachment._--The animal is attached, as already stated, to the sack of the Alepas by two threads, rising close together from the medio-dorsal line, near the posterior end of the second segment of the body. These threads are attached likewise close together at their further ends, by the antennæ, into which they enter. They are flattened and strong, yet quite flexible, with a somewhat sinuous surface: they were, in this specimen, 42/1000ths of an inch in length, and a little above 3/1000ths in diameter: where joined to the thoracic segment they were a little contracted. Their structure in this specimen could be made out (Pl. 24, fig. 1) with perfect distinctness. Their transparent outer tunic (_e_, fig. 1) is 1/2000ths of an inch in thickness, and is continuous with that (_d_) enveloping the whole body, but is abruptly and considerably thicker than this membrane; and hence a very slight collar is formed outside, round the line of junction of each thread with the body. The delicate corium (_c_) lining the external membrane of the body runs, at least someway, down these threads. It was likewise indisputably evident that the membrane (_b_), for I separated it by dissection, forming the great ovarian sack, together with the cellular contents of this sack (_a_), entered and extended down both threads. It should, also, be particularly observed, that the coarsely cellular matter within the ovarian sack, immediately that it entered the tube formed by the membrane of the ovarian sack, suddenly changed its appearance into a homogeneous, stiff, pulpy matter, which retained the same appearance all down the threads to within the antennæ. This finer matter readily separated from the coarser cellular matter within the sack, but was not divided from it by any septum or membrane. Some way within the threads, the corium, the membrane of the ovarian sack, and the contents appear (_e′_), as seen from the outside, to become, and perhaps really are, blended together. These threads could not have been originally formed of their present length, and must therefore have been added to during the growth of the animal; but from their entering the not-moulted antennæ, and from the animal being permanently attached by them, they cannot have grown, by means of the moulting of their integuments; hence I conclude that at each period of growth and exuviation they have been added to only at their upper ends, where there is a sort of collar, or line of growth; and where, I may remark, the lining corium is alone well developed. We shall presently see the bearing of these remarks.

These threads contract to about half their former diameter as they enter the old prehensile antennæ of the pupa, within which they are firmly attached. Each thread, with its three tunics apparently blended together, can be traced to the extremity of the disc-segment (_g_), where the included matter seems to have burst forth. The whole disc and the terminal segment of both antennæ are enveloped, close together, in cement, formed into two almost separate little capsules, by which they adhere very firmly to the integuments of the Alepas. The cement required to be removed before the antennæ could be plainly seen. The cement presented all the usual characters, namely, its homogeneous laminated structure and its yellowish colour. The cement in the case of the male Ibla, which is parasitic within the sack of the female Ibla, affects the corium and fibrous matter beneath the chitine-tunic, and causes them to adhere together, and thus prevents the male from being cast off each time that the inner tunic of the sack of the female is moulted: exactly so has the cement of the Proteolepas affected the integuments of the Alepas. The only difference between ordinary cement-ducts and the two threads here described is, that the ducts, in both cases formed by the prolongation of the coat of an ovarian receptacle, are here protected by a thick outer membrane, lined, at least in the upper part, by corium; whereas, in the Lepadidæ the two ducts are included within the peduncle, and are therefore protected by one common membrane, lined of course by corium; and this membrane, we shall presently see, is homologous with that separately investing the two threads.

The antennæ differ remarkably little, considering the anomalous character of the mature animal, from the same organ in other genera; they come nearest, perhaps, to the antennæ of Ibla. The length of the disc (_g_, fig. 1) and great succeeding segment (_f_) together is 40/6000ths of an inch. The lower segment has its basal articulation only slightly oblique, showing that, as in Alcippe and Ibla, it was probably articulated near the anterior end of the pupal shell: it is of nearly the same width throughout.[154] The disc (_g_) is remarkable from its great proportional length; it is hoof-shaped, with the outer side rather protuberant, and the end pointed. The ultimate segment (_h_) is of moderate size: as in Ibla, it has a shoulder or notch on its inner side near its end, bearing two long spines; and probably there were originally three or four spines on the square broad upper end, but these have been broken. This segment is articulated unusually near to the end of the disc.

[154] As I have given the measurements of the antennæ in so many
genera, I will give these: second (_f_, fig. 1) segment, 24/6000ths
of an inch in length, and (8-9)/6000ths in width. Disc, 16/6000ths
in length, and 8/6000ths in width. Ultimate segment, 6/6000ths (?)
in length, and 10/20,000ths (?) in breadth.

The foregoing remarks on the two threads by which Proteolepas is attached, are, independently of their relation to this individual animal, of considerable interest. In my volume on the Lepadidæ, I have stated, after repeated and rigorous examinations (for I was well aware how singular the facts were), that in _Conchoderma aurita_ and in some other genera, the cement-ducts, which entered the pupal antennæ, could be traced till they joined a gland, the coat of which gland was absolutely continuous with the coats of the adjoining and continuous ovarian tubes, of which it was only a modified portion; and what was still more remarkable, that the matter within the gland was continuous with, and differed only from, the cellular matter within the ovarian tubes and cæca (from which ova were in the act of formation), by being more homogeneous and more coherent. Furthermore, I have shown, that in Ibla an ovarian tube, becomes by a very small change, namely, by a double flexure and slight thickening of its coat, converted into a gland, and thus acquires the power of affecting the cellular ovarian matter and changing it into cement. Now, in Proteolepas, the great ovarian sack replaces the ovarian tubes and cæca; and we here see the very same relations even still more plainly; for the coat of the ovarian sack is indisputably continuous with that investing or forming the two cement-ducts within the two threads; and immediately that the coarse cellular matter, which within the ovarian sack is being converted into ova, enters the upper contracted end of the cement-duct, by some power, we must suppose, inherent in its coat, it is converted into cement, which debouches with all its usual properties through the pupal antennæ. I may venture to reaffirm that nothing could be plainer than this structure, or be in more striking conformity with my previous observations, given in the introduction to the Lepadidæ.

* * * * *

I can hardly express the perplexity which I felt when I first examined Proteolepas, and when I naturally mistook the mouth for the entire head, for I saw, as I thought, the antennæ in direct connection with the second segment of the body, posteriorly to the mouth! It was quite as monstrous and incredible an inversion of the laws of nature, as those fabulous half-human monsters, with an eye seated in the middle of their stomachs. After a time, I perceived that the following considerations removed all difficulty, and brought Proteolepas into the type of other cirripedes.

_Firstly_: in ordinary cirripedes, the two cement-ducts can be traced up from the cemented antennæ to the glands, formed by a part of the ovarian branching cæca; and the latter can be traced to where they enter, as two simple tubes, the body of the animal, at a medio-dorsal point, a little anteriorly to the prosoma, or second thoracic segment.[155] From what is actually seen in the complemental male of _Scalpellum Peronii_, and from what may be inferred from the structure of these parts in the pupæ of all cirripedes, there can be no doubt that if the ovarian cæca were in any case not developed, the cement-ducts would enter the body at the spot where the two simple ovarian tubes, which serve to unite the ovarian cæca with the true ovaria, do enter. Now if we look at the drawing (Pl. 25, fig. 7) of Proteolepas, we shall see that the cement-ducts enter the body at a medio-dorsal point, a little anteriorly to the second thoracic segment, and therefore in the normal position.

[155] This may be partially seen in the section, fig. 1, of
Balanus, on the same plate (25) with the figure of Proteolepas;
here (bearing in mind that Balanus is a much modified form)
(_z_) shows the pupal antennæ, within which, whilst young, the
cement-ducts are included, and are directly continuous with the
layer of branching ovarian cæca (_g_), which are prolonged up
to the ovaria as a pair of simple tubes (only one being here
represented), entering the body above the upper margin of the
prosoma (_c_). The prosoma of Balanus, I may add, answers to
the segment ^2 _t_ in fig. 7 of Proteolepas; (_e_) the mouth
in Balanus, of course corresponding with (_m_) the mouth of
Proteolepas; the segment ^1 _c_ and ^2 _t_ of the latter, are in
Balanus aborted or confluent, at least on the ventral surface; and,
lastly, the whole great shell of Balanus, the sack with its muscles
and the branchiæ, and the opercular valves with their muscles, are
all represented in Proteolepas merely by the outer membrane of the
two threads (_g_), which enter the pupal antennæ!

_Secondly_: the external membrane of the two threads, investing the two cement-ducts, it should be remembered, is not moulted, and is added to during growth (being lined internally by corium), only round the upper, collar-like edge.

_Thirdly_: the external covering or carapace of every young cirripede, at the period of its metamorphosis, enters, at its lower end, the cemented antennæ, in the form of two short tubular prolongations, by which alone, at first, the cirripede adheres to the surface of attachment; within these prolongations the cement-ducts are included. I have, moreover, seen instances, as in _Conchoderma aurita_ and in the male of Ibla and Alcippe, in which these tubular prolongations, lined internally by corium, were increased a little in length, so as to form a trouser-like termination to the peduncle. That the forked extremity should be a little more developed, and so be converted into a pair of short tubular threads, cannot be considered as very improbable.

_Fourthly_: in the male Ibla the capitulum is so much atrophied that it does not enclose the thorax or mouth, but still an elongated support or peduncle is left. But it would be no very violent assumption to imagine the peduncle, which does not essentially differ from the capitulum, to become likewise rudimental,--to grow smaller and smaller, and shorter and shorter, till the merest remnant was left at the spot where it entered the cemented antennæ. And in the last paragraph it has been shown that it would be no violent assumption to imagine this lower end of the peduncle, where it enters the antennæ, developed into two short thread-like prolongations.

_Lastly_: it is certain, from the existence of the prehensile antennæ, that Proteolepas was developed within a pupa, probably differing in no very essential respect from the pupæ of other cirripedes. Therefore, in accordance with all analogy, we may believe that the position[156] of the young Proteolepas (probably much coiled up, with a deep fold close under the mouth) within the pupa, the general form and structure of the latter, and the course of the cement-ducts, did not _essentially_ differ from the imaginary figure given, Pl. 25, fig. 6. Now, at the period of the metamorphosis, let us imagine that no general covering or carapace was formed, except a small portion on the ventral surface, round the cemented antennæ. Let us further suppose this remnant to be specially developed (as in the case of some cirripedes) into a short trouser-like prolongation, entering the antennæ; and subsequently, in accordance with the almost universal laws of growth in cirripedes, that this portion was never moulted, but continued to be added to, during growth, only at its upper end. By this means we should produce every leading peculiarity of the _Proteolepas bivincta_. As this parasite lives within the sack of another cirripede, and is protected by the capitulum of the latter, we can understand, in accordance with the usual admirable economy of nature, the absence of any general covering for its body. We can now, also, understand the structure and manner of growth of the two threads by which it is bound to its prey; and the connection, at first so strange and perplexing, between the old pupal antennæ and the second segment of the thorax. I am convinced that no other explanation than that here given, will accord with the relations of the several parts and organs of Proteolepas. Consequently, I fully believe that we here see an articulate animal in which the whole of the three anterior segments of the head have been, during the act of metamorphosis, absolutely aborted, with the exception of a mere rudiment on the ventral surface, near the anterior end, round the old antennæ, and which rudiment has been specially developed as a covering for the two cement-ducts. As the pupal antennæ are, homologically, the second pair of antennæ, we may further infer that this modified remnant of the carapace, investing the two threads, belongs to the third cephalic segment.

[156] Any one who has not specially attended to the metamorphoses
of ordinary cirripedes, who looks at the imaginary figure of
the young Proteolepas, will feel much surprise at the relative
positions of the parts; for the mouth and the first and even
second segments of the body stand posteriorly (_i. e._ above in
the figure) to the succeeding segments of the body, in relation to
the carapace of the pupa; but this is only in accordance with the
remarkable change in position (as explained in the introduction,
p. 123, pl. 30, fig. 2), amounting almost to inversion, which the
whole thorax of every young cirripede undergoes within the pupa,
whilst the anterior cephalic portions and general covering are
developed conformably with the pupal carapace, whence it arises
that the _dorsal_ surface of that part of the thorax immediately
succeeding the mouth becomes attached to the _ventral_ internal
surface of the carapace. I believe that the peculiar flattened
dorsal outline of the first two segments of the body of Proteolepas
is due to these parts having been formed in contact (as represented
in pl. 25, fig. 6) with the straight ventral surface of the
carapace of the pupa. To place the young Proteolepas, and at the
same time the carapace of the pupa, with all the parts in proper
homological sequence, it would be necessary to seize the posterior
end of the abdomen (_a_), and pull till the dorsal surfaces of the
first and second segments of the body, separated from the ventral
internal surface of the carapace, and stood posteriorly (_i. e._
above in figure) to the mouth, which latter would thus also have to
rotate a quarter of a circle, so that the orifice would come to be
directed outwards. Then every part would stand, in accordance with
the archetype crustacean structure, in due order; but the three
confluent anterior cephalic segments, forming the front part and
carapace of the pupa, would, as in the case of all cirripedes, be
of disproportionately large size in relation to the rest of the
body.

SYNOPSIS

ET

INDEX SYSTEMATICUS.

_Ordinum, Familiarum, et Generum Cirripediorum et recentium et fossilium._

CLASSIS CRUSTACEA.

Sub-classis CIRRIPEDIA.

Crustacea ex anteriore capitis parte defixa, cæmento in hunc usum ex ovariorum portione ad id specialiter modificatâ emisso. Archetypus è segmentis 17 compositus, quorum 3 priora magna, in carapacem sæpissimè conformata, quæ non omnino exuitur et varios motus efficit: antennæ nullæ: oculi rudimentarii: os prominens, formatum è labro, palpis, mandibulis, et duobus maxillarum paribus, quæ omnia partim confluunt: thorax ad superficiem internam sternalem carapacis affixus, plerumque cum membrorum captantium biramorum, multiarticulorum paribus 6: abdomen plerumque rudimentarium: branchiæ, si quæ adsunt, ad inferiora carapacis latera affixæ: plerumque bisexualia; in unisexualibus, mares fœminis parasitice inserti: penis unicus, plerumque probosciformis, ad posteriorem abdominis extremitatem situs: oviductus nulli: metamorphoses multiplices.

ORDO I. THORACICA. (Darwin, 'Balanidæ,' p. 30.)

Cirripedia quibus pro carapace est aut capitulum pedunculatum, aut testa operculata cum basi. Corpus è 6 thoracicis segmentis, ferè cum 6 cirrorum paribus, constat. Abdomen rudimentarium, sed sæpe cum appendiculis caudalibus. Oris labrum motus proprios non efficit. Larva primò monocula cum 3 crurum paribus, postremò binocula cum 6 crurum thoracicorum paribus.

Familia 1. BALANIDÆ. (Darwin, 'Balanidæ,' p. 33.)

Cirripedia sine pedunculo: scuta et terga musculis depressoribus instructa: reliquæ testæ valvæ inter se immobiliter conjunctæ.

Sub-Familia 1. BALANINÆ. (Darwin, 'Balanidæ,' p. 175.)

Rostrum cum radiis, sed sine alis; valvæ testæ laterales omnes, ex uno latere alis, ex altero radiis instructæ: parietes ferè aut porosi aut ad interiorem superficiem longitudinaliter costati.

[_Sectio_ †.]

Scutum et tergum inter se articulata aut mutuò interclusa: branchiarum unaquæque ex unicâ plicâ constat.

1. _Genus_--BALANUS, _Auctorum_. (Darwin, 'Balanidæ,' p. 177.)

Valvæ testæ 6; basis calcarea aut membranacea; valvæ operculares subtriangulares.

2. _Sub-Genus_--ACASTA, _Leach_. (Darwin, 'Balanidæ,' p. 302.)

Valvæ testæ 6; parietes et basis non porosa; basis calcarea, cyathiformis, non elongata. Spongiis, aut rarò Isidis cortici, affixa.

3. _Genus_--TETRACLITA, _Schumacher_. (Darwin, 'Balanidæ,' p. 321.)

Valvæ testæ 4; interdum inter se externè confluentes: parietes poris perforati, multis plerumque seriebus; basis plana, irregularis, calcarea aut membranacea.

4. _Genus_--ELMINIUS, _Leach_. (Darwin, 'Balanidæ,' p. 345.)

Valvæ testæ 4; parietes non porosi; basis membranacea.

5. _Genus_--PYRGOMA, _Leach_. (Darwin, 'Balanidæ,' p. 354.)

Valvæ testæ in unam confluentes; basis cyathiformis aut subcylindrica, coraliis affixa.

6. _Sub-Genus_--CREUSIA, _Leach_. (Darwin, 'Balanidæ,' p. 375.)

Valvæ testæ 4, radiis instructæ; basis cyathiformis, coraliis affixa.

7. _Genus_--CHELONOBIA, _Leach_. (Darwin, 'Balanidæ,' p. 382.)

Valvæ testæ admodum crassæ, 6; sed ex iis, valva rostralis intùs è tribus valvis rudimentariis conjunctis constat; basis membranacea; scuta angusta, tergis cristâ articulari corneâ conjuncta.

[_Sectio_ ††.]

Scutum et tergum (ubi ambo adsunt) non inter se articulata; basis membranacea; parietes sæpe profundè plicati, laminâ exteriore, ad basin versâ, plerumque imperfectâ; branchiarum unaquæque e duobus plicis constat. Testa vertebratis vivis affixa.

8. _Genus_--CORONULA, _Lamarck_. (Darwin, 'Balanidæ,' p. 397.)

Valvæ testæ 6; æquali latitudine; parietes tenues, profundè plicati, plicis cavitates infrà solùm apertas efficientibus; valvæ operculares orificio testæ multo minores. Cetaceis affixa.

9. _Genus_--PLATYLEPAS, _J. E. Gray_. (Darwin, 'Balanidæ,' p. 424.)

Valvæ testæ 6; unaquæque bilobata et intùs producta, ita ut 6 medias costas longitudinales efficiant, quæ basin membranaceam extrorsùs convexam sustinent.

10. _Genus_--TUBICINELLA, _Lamarck_. (Darwin, 'Balanidæ,' p. 430.)

Valvæ testæ 6, æquali latitudine; testa subcylindrica, orificio latiore quam basis, pluribus cristis transversis virgata. Cetaceis affixa.

11. _Genus_--XENOBALANUS, _Steenstrup_. (Darwin, 'Balanidæ,' p. 438.)

Testa pæne rudimentaria, stelliformis, è valvis 6 formata, è quarum medio corpus longum pedunculiforme exoritur; valvæ operculares absunt. Cetaceis affixus.

Sub-Familia 2. CHTHAMALINÆ. (Darwin, 'Balanidæ,' p. 446.)

Rostrum cum alis sed sine radiis; valvæ rostro-laterales utrinque sine alis; parietes non porosi.

12. _Genus_--CHTHAMALUS, _Ranzani_. (Darwin, 'Balanidæ,' p. 447.)

Valvæ testæ 6; basis membranacea, sed interdum ad speciem calcarea, ideò quod parietes inflectuntur.

13. _Genus_--CHAMÆSIPHO, _Darwin_. ('Balanidæ' p. 470.)

Valvæ testæ 4, suturis sæpe admodùm obliteratis; basis membranacea.

14. _Genus_--PACHYLASMA, _Darwin_. ('Balanidæ,' p. 475.)

Valvæ testæ, conchâ recenter natâ, 8; adultâ aut 6, aut ad speciem 4, ideò quod valvæ laterales arctè conjunguntur; basis calcarea.

15. _Genus_--OCTOMERIS, _G. B. Sowerby_. (Darwin, 'Balanidæ,' p. 482.)

Valvæ testæ 8; radii marginibus crenatis; basis membranacea.

16. _Genus_--CATOPHRAGMUS, _G. B. Sowerby_. (Darwin, 'Balanidæ,' p. 485.)

Valvæ testæ interiores 8, cum pluribus exterioribus parvarum supplementalium valvarum verticillis; basis aut membranacea aut calcarea.

Familia 2. VERRUCIDÆ. (Darwin, 'Balanidæ,' p. 495.)

Cirripedia sine pedunculo; scuta et terga, musculis depressoribus non instructa, ex uno latere tantum mobilia, ex altero cum carinâ et rostro in testam asymmetricam immobiliter conjuncta.

1. _Genus_--VERRUCA, _Schumacher_. (Darwin, 'Balanidæ,' p. 496.)

Familia 3. LEPADIDÆ. (Darwin, 'Lepadidæ,' p. 8, et 'Balanidæ,' p. 526.)

Cirripedia pedunculo flexili, musculis instructo; scuta et terga (si qua adsunt) musculis depressoribus non instructa; reliquæ valvæ (si quæ adsunt) in annulum immobilem non conjunctæ.

1. _Genus_--LEPAS, _Linn._ (Darwin, 'Lepadidæ,' p. 67.)

Valvæ 5, approximatæ; carina sursùm inter terga extensa, deorsùm aut furcâ infossâ aut disco externo terminata; scuta subtriangula, umbonibus ad angulum rostralem positis.

2. _Genus_--PŒCILASMA, _Darwin_. ('Lepadidæ,' p. 99.)

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.

3. _Genus_--DICHELASPIS, _Darwin_. ('Lepadidæ,' p. 115.)

Valvæ 5, quæ ferè pro septem haberi possent, scuto in segmenta planè duo, ad angulum autem rostralem conjuncta, diviso; carina plerumque sursum inter terga extensa, deorsum aut disco infosso aut furcâ aut calyce terminata.

4. _Genus_--OXYNASPIS, _Darwin_. ('Lepadidæ,' p. 133.)

Valvæ 5, approximatæ; scutorum umbones in medio marginis occludentis positi; carina rectangulè flexa, sursùm inter terga extensa, termino basali simpliciter concavo.

5. _Genus_--CONCHODERMA, _Olfers_. (Darwin, 'Lepadidæ,' p. 136.)

Valvæ 2 ad 5, minutæ, inter se remotæ; scuta bi- aut tri-lobata, umbonibus in medio marginis occludentis positis; carina arcuata, terminis utrinque pæne similibus.

6. _Genus_--ALEPAS, _S. Rang_. (Darwin, 'Lepadidæ,' p. 156.)

Capitulum aut sine valvis, aut scutis corneis, pæne abditis.

7. _Genus_--ANELASMA, _Darwin_. ('Lepadidæ,' p. 169.)

Capitulum sine valvis; aperturâ amplâ; pedunculus fimbriatus, sub-globosus, infossus.

8. _Genus_--ALCIPPE, _Hancock_. (Darwin, 'Balanidæ,' p. 529.)

(Fœm.) Capitulum sine valvis, aperturâ spinosâ; pedunculus ad basalem extremitatem crescit; superficie rostrali depressâ et disco corneo tectâ; capitulum et pedunculus in cavitate conduntur, ab ipso cirripedio formatâ.

9. _Genus_--IBLA, _Leach_. (Darwin, 'Lepadidæ,' p. 180.)

(Herm. et Fœm.) Valvæ 4, corneæ; pedunculus spinis corneis, persistentibus vestitus.

10. _Genus_--SCALPELLUM, _Leach_. (Darwin, 'Lepadidæ,' p. 215, et 'Lepad. Foss.' p. 13.)

(Herm. et Fœm.) Valvis 12 ad 15; lateribus verticilli inferioris quatuor vel sex, lineis incrementi plerumque convergentibus; sub-rostrum rarissime adest; pedunculo squamifero, rarissime nudo.

CHARACTERES VALVARUM IN SPECIEBUS FOSSILIBUS.

Carina angusta, introrsùm arcuata, ab apice ad marginem basalem paululum dilatata; carinæ parietes valde inflexi, costis manifestis a tecto plerumque disjuncti; in multis speciebus intra-parietibus instructa; intraparietes nonnunquam supernè producti ultra umbonem carinæ, qui fit inde subcentralis; carinæ parietum lineæ incrementi perobliquæ. Scuta plerumque subconvexa et tenuia, trapezoidea; marginibus tergalibus lateralibusque angulo insigni disjunctis.

11. _Genus_--POLLICIPES, _Leach_. (Darwin, 'Lepadidæ,' p. 293, et 'Lepad. Foss.' p. 42.)

Valvæ ab 18 usque ad 100 et amplius; lateribus verticilli inferioris multis; lineis incrementi deorsùm ordinatis; subrostrum semper adest; pedunculus squamiferus.

CHARACTERES VALVARUM IN SPECIEBUS FOSSILIBUS.

Carina ab apice ad marginem basalem multum dilatata, apice plerumque liberè prominente; carinæ parietes à tecto non distincté separati, lineis incrementi parietum parum obliquis. Scuta plerumque subsolida, convexa, subtrigonalia, margine tergo-laterali plus minusve eminente, sed non angulo in margines duos discreto.

12. _Genus_--LITHOTRYA, _G. B. Sowerby_. (Darwin, 'Lepadidæ,' p. 332.)

Valvæ 8, si inter eas parvum (sæpe rudimentale) rostrum et duo parva latera numerentur; incrementi lineis concinnè crenatis; pedunculus squamis calcareis parvis vestitus, in verticillis superioribus crenatis, aut calyci basali calcareo aut discorum ordini affixus.

13. _Genus_--LORICULA, _G. B. Sowerby, jun._ (Darwin, 'Lepad. Foss.' p. 81.)

Capitulo decem (fortasse) valvis instructo. Pedunculo seriebus decem squamarum lævium calcarearum instructo; sex lateralibus multum transversè elongatis; quatuor terminalibus angustis; secundùm pedunculi margines rostralem et carinalem decurrit sutura medialis recta, squamis non intersecantibus.

ORDO II. ABDOMINALIA. (Darwin, 'Balan.' p. 563.)

Cirripedia quibus carapax lageni-formis est; corpus ex 1 cephalico, 7 thoracicis, 3 abdominalibus segmentis constat; quorum abdominalia tribus cirrorum paribus muniuntur; thoracica membris carent. Oris labrum longè producitur et motus proprios efficit; œsophagi inferior extremitas dentibus munitur. Larva, primò ovöides, sine externis membris, sine oculo; postremò binocula, thoracicis cruribus nullis.

1. _Genus_--CRYPTOPHIALUS, _Darwin_. ('Balanidæ,' p. 566.)

ORDO III. APODA. (Darwin, 'Balan.' p. 587.)

Cirripedia quibus carapax ad duo separata fila (quæ defigendo inserviunt) redactus est. Corpus ex 1 cephalico, 7 thoracicis, 3 abdominalibus segmentis constat, quæ omnia cirris carent. Os suctorium, mandibuli et maxillæ (dorsis inter se appositis) cucullo includuntur, qui è labro et palpis confluentibus formatur. Metamorphoses incognitæ.

1. _Genus_--PROTEOLEPAS, _Darwin_. ('Balanidæ,' p. 589.)

SYNOPSIS

ET

INDEX SYSTEMATICUS SPECIERUM,

_Et recentium, et fossilium_.[157]

[157] In hâc portione Synopsis, Auctorum nomina referunt solummodo
ad species.

ORDO I. THORACICA.

Fam. BALANIDÆ.

Sub-Fam. BALANINÆ.

[_Sectio_ †.]

1. _Genus_--BALANUS.

_Sectio_ A.

Parietes et basis et radii poris perforati.

_Sectio_ B.

Parietes et basis interdum poris perforati; radii nunquam; testæ axis rostro-carinalis elongatus; basis cymbiformis, Gorgoniis et Milleporis affixa.

_Sectio_ C.

Parietes et basis semper poris perforati; radii nunquam.

_Sectio_ D.

Parietes semper poris perforati; basis et radii nunquam.

_Sectio_ E.

Basis membranacea.

_Sectio_ F.

Parietes et radii nunquam, basis interdum, poris perforata; basis interdum admodum tenuis, adeo ut vix distingui possit.

[_Sectio_ A.]

1. _Balanus tintinnabulum_, Linn. (Darwin, 'Balanidæ,' p. 194, Tab. 1 et 2, fig. 1.)

B. testâ à roseâ ad atropurpuream variante, sæpe longitudinaliter virgatâ et costatâ. Orificio plerumque integro, interdum dentato. Scuti cristâ articulari latâ et reflexâ. Tergi margine basali plerumque in contrariis calcaris partibus rectam lineam formante.

_Hab._--In tepidis et torridis ubique maribus. _Foss._ in Europâ.

2. _Balanus tulipiformis_, Ellis. (Darwin, 'Balanidæ,' p. 204, Tab. 2, fig. 2.)

B. testâ, obscurè roseâ, interdum purpurascente; orificio dentato. Scuto externè admodum lævi membranâ tecto. Tergi musculorum depressorum cristis distinctis.

_Hab._--In Europâ meridionali et Madeirâ.

3. _Balanus psittacus_, Molina. (Darwin, 'Balanidæ,' p. 206, Tab. 2, fig. 3.)

B. testâ pallidè roseâ, sordidâ; orificio hexagonali. Scuti cristâ articulari minimâ, quæ cum adductoris cristâ, admodum prominente, confluit; musculo depressore laterali tubulari cavitate locato, quæ sursùm ad valvæ apicem extendit. Tergi apice producto, aculeato, purpureo; calcare ab angulo basi-scutali propiùs quam suâ ipsius latitudine distante.

_Hab._ et _foss._ in Americâ meridionali.

4. _Balanus Capensis_, Ellis. (Darwin, 'Balanidæ,' p. 209, Tab. 2, fig. 4.)

B. testâ colore lucidè-roseo, umbratâ et sæpe longitudinaliter virgatâ. Scuto ut in B. psittaco. Tergi apice producto aculeato, albo; calcare ab angulo basi-scutali suâ ipsius latitudine distante.

_Hab._--In Africâ meridionali.

5. _Balanus nigrescens_, Lamarck. (Darwin, 'Balanidæ,' p. 210, Tab. 2, fig. 5.)

B. testâ cinereâ, pallidè-cæruleo aut atro-cæruleo, aut albo tinctâ. Scuti cristâ articulari parvâ, deorsùm in parvum, acutum aculeum desinente; adductoris cristâ prominente. Tergi apice producto, aculeato.

_Hab._--In Australiâ.

6. _Balanus decorus_, Darwin. ('Balanidæ,' p. 212, Tab. 2, fig. 6.)

B. parietibus pallidè-roseis: radiis aliquanto intensioribus. Scuti cristâ articulari parvâ. Tergi sulco longitudinali admodum tenui et aperto; marginibus basalibus utrinque ad calcar declivibus.

_Hab._--In Novâ Zealandiâ.

7. _Balanus vinaceus_, Darwin. ('Balanidæ,' p. 213, Tab. 2, fig. 7.)

B. testâ fusco-purpureâ; parietum laminâ interiore cancellatâ. Scuto longitudinaliter et tenuiter striato. Tergi sulco longitudinali tenui et aperto: marginibus basalibus utrinque ad calcar declivibus.

_Hab._--In occidentali littore Americæ merid.

8. _Balanus Ajax_, Darwin. ('Balanidæ,' p. 214, Tab. 3, fig. 1.)

B. testâ globoso-conicâ, sæpe in axe rostro-carinali elongatâ, pallidè-roseâ, lævi, admodum crassâ: tubis parietalibus prope marginem basalem, cylindricis et minimis. Scuti cristâ articulari latâ, reflexâ.

_Hab._--In Arch. Philippino.

[_Sectio_ B.]

9. _Balanus stultus_, Darwin. ('Balanidæ,' p. 216, Tab. 3, fig. 2.)

B. parietibus et basi porosis: testâ albâ aut purpurâ leviter tinctâ. Scuti margine basali in medio prominente. Tergi sulco longitudinali supernè clauso; calcare angulo basi-scutali non approximato.

_Hab._--In Indiâ occident. et orient.

10. _Balanus calceolus_, Pallas. (Darwin, 'Balanidæ,' p. 218, Tab. 3, fig. 3.)

B. parietibus et basi porosis. Scuto musculi depressoris lateralis fossâ parvâ, profundâ.

_Hab._--In Africâ occidentali et Indiâ. _Foss._ in Angliâ.

11. _Balanus galeatus_, Linn. (Darwin, 'Balanidæ,' p. 220, Tab. 3, fig. 4.)

B. parietibus non porosis: basi porosa. Tergi apice, propter cristæ articularis magnitudinem, quadrato.

_Hab._--In Americâ sept. et Indiâ occident.

12. _Balanus cymbiformis_, Darwin. ('Balanidæ,' p. 221, Tab. 3, fig. 5.)

B. parietibus et basi non porosis. Scuti et tergi cristis articularibus minimis. Tergo lato, pæne æquilaterali.

_Hab._--In Indiâ.

13. _Balanus navicula_, Darwin. ('Balanidæ,' p. 221, Tab. 3, fig. 6.)

B. parietibus et basi non porosis: valvis testæ carino-lateralibus admodùm angustis, latitudine à vertice ad imum pæne æquâ. Radiorum marginibus suturalibus lævibus. Scuto externè longitudinaliter striato.

_Hab._--In Indiâ.

[_Sectio_ C.]

14. _Balanus trigonus_, Darwin. ('Balanidæ,' p. 223, Tab. 3, fig. 7.)

B. parietibus costatis, purpureo-rubris, maculatis: orificio lato, trigonali, vix dentato. Scuto crasso, fossularum seriebus longitudinalibus 1 ad 6. Tergo sine sulco longitudinali; calcare truncato ad plenùm 1/3 valvæ latitudine.

_Hab._--In Arch. Indiæ Orient.: Australiâ: Californiâ: Peruviâ.

15. _Balanus spongicola_, Brown. (Darwin, 'Balanidæ,' p. 225, Tab. 4, fig. 1.)

B. parietibus plerumque lævibus, interdum longitudinaliter plicatis; roseis; orificio dentato: scuto longitudinaliter striato: tergum, apice producto, sine sulco longitudinali; calcare truncato 1/3 valvæ latitudine.

_Hab._--In Europâ meridionali et mediâ, Africâ meridionali; _var._ in Indiâ occidentali. _Foss._ in Angliâ, in "Miocenâ Formatione."

16. _Balanus lævis_, Bruguière. (Darwin, 'Balanidæ,' p. 227, fig. 2.)

B. testâ aut fuscâ membranâ testâ, aut nudâ et albâ, aut pallide-purpureâ: orificio parvo: radiis minimis: scuto 1 aut 2 sulcis longitudinalibus profundis.

_Hab._--In littore occidentali Americæ utriusque.

17. _Balanus perforatus_, Bruguière. (Darwin, 'Balanidæ,' p. 231, Tab. 4, fig. 3, et Tab. 5, fig. 1.)

B. testâ sordidâ, pallidè-purpureâ aut albâ aut cinereâ, lævi aut propter corrosionem longitudinaliter tenuiter costatâ; vaginâ purpureâ; orificio plerumque parvo: radiis plerumque angustis aut nullis: scuto introrsus cristâ brevi minutâ sub cristam adductoris prominentem proximè et parallelè positâ: tergi apice aliquantum producto.

_Hab._--In Europâ meridionali et mediâ; in Africâ occidentali.

18. _Balanus concavus_, Bronn. (Darwin, 'Balanidæ' p. 235, Tab. 4, fig. 4.)

B. testâ, albo cum roseo aut obscurè purpureo longitudinaliter striatâ; interdum pure albâ: scuto longitudinaliter tenuiter striato; internè adductoris cristâ admodum aut modicè prominente.

_Hab._--In Peruviâ, Californiâ, Arch. Philippino, Australiâ. Et _foss._ in Europâ, Americâ septent. et meridionali.

19. _Balanus amphitrite_, Darwin. ('Balanidæ,' p. 240, Tab. 5, fig. 2.)

B. testâ purpureo aut roseo longitudinaliter striatâ; striis interdum confluentibus; interdum pure albâ: scutum internè adductoris cristâ prominente.

_Hab._--In tepidis et torridis ubique maribus.

20. _Balanus pœcilus_, Darwin. ('Balanidæ,' p. 246, Tab. 5, fig. 3.)

B. testâ obscurè rubrâ albo maculatâ scuto internè adductoris cristâ nullâ tergi calcare præcisè truncato, ferè 1/3 valvæ latitudine.

_Hab._--In littore occident. Americæ merid.

21. _Balanus eburneus_, A. Gould. (Darwin, 'Balanidæ,' p. 248, Tab. 5, fig. 4.)

B. testâ flavescente albâ: scuto longitudinaliter tenuiter striato: tergi calcare truncato, margine basi-carinali ferè admodùm excavato; margine carinali supernè prominente.

_Hab._--In Americâ septent. et Indiâ occident.

22. _Balanus improvisus_, Darwin. ('Balanidæ,' p. 250, Tab. 6, fig. 1.)

B. testâ albâ: radiis angustis, marginibus superioribus lævibus, leniter arcuatis, admodùm obliquis: tergi sulco longitudinali; calcaris, termino rotundato.

_Hab._--In Europâ, et Americæ utriusque littoribus orient. et occident.

23. _Balanus nubilus_, Darwin. ('Balanidæ,' p. 253, Tab. 6, fig. 2.)

B. testâ albâ, irregulari: basi alicubi imperfecte porosâ: scuti cristâ articulari minutâ; adductoris cristâ prominente, fossam profundam musculo depressori præbente: tergo introrsus purpureâ maculâ majore notato; apice producto, purpureo.

_Hab._--In Californiâ.

24. _Balanus corrugatus_, Darwin. ('Balanidæ,' p. 254, Tab. 6, fig. 3.)

B. testâ albâ longitudinaliter plicatâ: radiis angustis: scuto internè sine adductoris cristâ.

_Foss._ in Italiâ.

[_Sectio_ D.]

25. _Balanus porcatus_, Da Costa. (Darwin, 'Balanidæ,' p. 256, Tab. 6, fig. 4.)

B. testâ albâ, plerumque longitudinaliter acutè costatâ: radiorum marginibus superioribus pæne basi parallelis: scuto longitudinaliter striato; tergi apice producto, purpureo.

_Hab._ et _foss._ in Europâ, et Americâ septent. et regionibus Arcticis.

26. _Balanus patellaris_, Spengler. (Darwin, 'Balanidæ,' p. 259, Tab. 6, fig. 5.)

B. testâ depressâ fuscâ, plerumque obscuro-violaceo longitudinaliter striatâ: radiorum marginibus superioribus (in adultis speciminibus) rotundatis, superficie sulcis tenuibus basi parallelis: basi interdùm poris imperfectis perforatâ: scuto internè cum adductoris cristâ.

_Hab._--In Indiâ et Arch. Philippino.

27. _Balanus crenatus_, Bruguière. (Darwin, 'Balanidæ,' p. 261, Tab. 6, fig. 6.)

B. testâ albâ: radiorum marginibus superioribus obliquis, asperis, rectis: scuto sine adductoris cristâ: tergi calcare rotundato.

_Hab._ et _foss._ in Europâ, et Americâ septent. et regionibus Arcticis, et Indiâ occident. et Africâ meridionali.

28. _Balanus glandula_, Darwin. ('Balanidæ,' p. 265, Tab. 7, fig. 1.)

B. testâ albâ; parietum laminâ internâ longitudinaliter et fortiter costatâ, poris imperfectis et minutis, interdùm alicubi nullis: radiis angustis marginibus superioribus rotundatis: scuto cum adductoris cristâ: tergi calcare truncato, rotundato.

_Hab._--In Californiâ, et Oceano Pacifico meridion.

[_Sectio_ E.]

29. _Balanus balanoides_, Linn. (Darwin, 'Balanidæ,' p. 267, Tab. 7, fig. 2.)

B. parietibus aut solidis, aut cancellatis, aut (rarò) unicâ pororum serie formatis: tergi calcare obtuso aut acuto.

_Hab._--In Europâ et Americâ septent. et regionibus Arcticis.

30. _Balanus cariosus_, Pallas. (Darwin, 'Balanidæ,' p. 273, Tab. 7, fig. 3.)

B. parietibus crassis, pluribus seriebus pororum inæqualium formatis; tergo angusto, apice rostrato, calcare acuminato.

_Hab._--In littore occident. Americæ septent. et Freto Behringi et Insulis Kuriliis.

31. _Balanus declivis_, Darwin. ('Balanidæ,' p. 275, Tab. 7, fig. 4.)

B. parietibus solidis: rostro, carinâ et valvis carino-lateralibus pæne duplo longiore, basi igitur obliquâ: tergi calcare truncato, 1/2 valvæ latitudine.

_Hab._--In Indiâ occident.

[_Sectio_ F.]

32. _Balanus Hameri_, Ascanius. (Darwin, 'Balanidæ,' p. 277, Tab. 7, fig. 5.)

B. testâ albâ: radiorum marginibus superioribus obliquis, lævibus, arcuatis; aciebus suturalibus lævibus: basi solidâ: scuto longitudinaliter, debiliter striato: tergi calcare angusto.

_Hab._ et _foss._ in Europâ septent. et Americâ septent.

33. _Balanus amaryllis_, Darwin. ('Balanidæ,' p. 279, Tab. 7, fig. 6.)

B. testâ subroseo-purpureo striatâ, aut obnubilatâ; interdùm purè albâ: radiis angustis, marginibus superioribus obliquis lævibus, arcuatis: basi porosâ: scuto longitudinaliter planè striato: tergi calcare angusto.

_Hab._--In Indiâ, et Arch. Indiæ orient. et Australiâ septent.

34. _Balanus allium_, Darwin. ('Balanidæ,' p. 281, Tab. 7, fig. 7.)

B. testâ pallidè purpuratâ, radiis latis, marginibus superioribus non obliquis: basi porosâ: scuto lineis incrementi crenatis: tergi calcare admodum brevi, truncato, 1/2 valvæ latitudine.

_Hab._--In Australiâ septent.

35. _Balanus cepa_, Darwin. ('Balanidæ,' p. 283, Tab. 7, fig. 8.)

B. testâ sordidè rubro-purpureâ, abruptè conicâ: radiis angustis: basi obscurè porosâ: scuto lineis incrementi crenatis: tergi calcare truncato, dimidiâ valvæ latitudine, et infrà angulum basi-scutalem dependente, usque ad 1/2 sui ipsius latitudinem.

_Hab._--In Japaniâ.

36. _Balanus quadrivittatus_, Darwin. ('Balanidæ,' p. 284, Tab. 8, fig. 1.)

B. testâ abruptè conicâ, quatuor vittis longitudinalibus transversè positis: radiorum marginibus superioribus obliquis: basi tenui, solidâ: scuto, lineis incrementi lævibus; musculi depressoris lateralis fossâ distinctâ nullâ: terga ut in _B. cepâ_.

_Hab._--In Archipel. Indiæ orient.

37. _Balanus terebratus_, Darwin. ('Balanidæ,' p. 285, Tab. 8, fig. 2.)

B. testâ albâ, costis longitudinalibus fortibus, margine basali in longos aculeos producto: basi concavâ non porosâ, lineis radiantibus fortiter costatâ; spatio intercostali foraminibus minutis rotundatis sæpe duplici serie, cribrosè perforato.

_Hab._--(?)

38. _Balanus vestitus_, Darwin. ('Balanidæ,' p. 286, Tab. 8, fig. 3.)

B. testâ subroseo-purpureâ aut albâ, membranâ aurantiacâ vestitâ: radiorum loco, meris fissuris: basi solidâ: scuto, cristâ adductoris acutâ curvatâ; musculi depressoris cristæ adsunt: tergi calcare brevi, truncato, 1/3 valvæ latitudine.

_Hab._--In Australiâ et Novâ Zealandiâ.

39. _Balanus imperator_, Darwin. ('Balanidæ,' p. 288, Tab. 8, fig. 4.)

B. testâ internè imperatorio-purpureâ: parietibus crassis margine interno basali spinis et cristis irregularibus aspero: radiis angustis: basi admodùm tenui, solidâ: scuto cum musculorum depressorum rostralium et lateralium cristis: tergi calcare ad finem rotundato.

_Hab._--In Australiâ.

40. _Balanus flosculus_, Darwin. ('Balanidæ,' p. 290, Tab. 8, fig. 5.)

B. testâ purpureâ aut sordide-albâ, parietum margine basali spinis et cristis irregularibus asperâ: radiis angustis aut nullis: basi quam tenuissimâ, ad speciem nullâ: scuto cum musculi depressoris lateralis cristis: tergo admodùm angusto, calcare acuminato.

_Hab._--In Americæ merid. littore occid.

41. _Balanus bisulcatus_, Darwin. ('Balanidæ,' p. 293, Tab. 8, fig. 6.)

B. radiorum marginibus superioribus obliquis, lævibus; aciebus suturalibus lævibus: basi poris magnis perforatâ: scuto angusto, sulcis longitudinalibus 2 ad 4: tergi calcare brevissimo dimidiâ valvæ latitudine.

_Foss._ in Angliâ, et Galliâ et Belgio. "Miocenâ Formatione."

42. _Balanus dolosus_, Darwin. ('Balanidæ,' p. 295, Tab. 8, fig. 7.)

B. radiorum marginibus superioribus obliquis lævibus: aciebus suturalibus item lævibus: basi poris magnis perforatâ: tergi calcare non admodum brevi, 1/3 valvæ latitudine.

_Foss._ in Angliâ. "Pliocenâ, et miocenâ Formationibus."

43. _Balanus unguiformis_, J. de C. Sowerby. (Darwin, 'Balanidæ,' p. 296, Tab. 8, fig. 8.)

B. parietibus tenuibus, interdum poris perforatis: radiorum marginibus superioribus obliquis; aciebus suturalibus tenuissimè crenatis: basi solidâ: tergi calcare angusto, obtuso.

_Foss._ in Angliâ et Belgio. "Eocenâ Formatione."

44. _Balanus varians_, Darwin. ('Balanidæ,' p. 298, Tab. 8, fig. 9.)

B. parietibus modicè crassis; radiorum marginibus superioribus perobliquis; aciebus suturalibus pæne lævibus aut tenuiter crenatis: basi tenuiter porosâ: tergi calcare, parvo, angusto, obtuso.

_Foss._ in Patagoniâ.

45. _Balanus inclusus_, Darwin. ('Balanidæ,' p. 299, Tab. 8, fig. 10.)

B. testâ rufo-fuscâ: radiis latis, marginibus superioribus aut non obliquis aut modicè; aciebus suturalibus cum septis planè denticulatis: basi porosâ: scuto sine adductoris cristâ: tergi calcare subangusto.

_Foss._ in Angliâ et Germaniâ. "Miocenâ Formatione."

2. _Sub-Genus_--ACASTA.

1. _Acasta spongites_, Poli. (Darwin, 'Balanidæ,' p. 308, Tab. 9, fig. 1.)

A. parietibus carino-lateralibus ferè 1/6 parietum lateralium latitudine: superficie internâ parietum plerumque debiliter costatâ: scuti cristâ articulari ad extremitatem inferiorem abruptè præcisâ: tergi calcare truncato rotundato, ferè 1/3 valvæ latitudine.

_Hab._--In Europâ et Africâ meridion.

2. _Acasta sulcata_, Lamarck. (Darwin, 'Balanidæ,' p. 310, Tab. 9, fig. 2.)

A. parietibus carino-lateralibus ferè 1/6 parietum lateralium latitudine: parietum superficie internâ plerumque fortiter costatâ: basis acie fortiter crenatâ: testæ orificio sub-exiguo: tergi calcare plerumque truncato, pæne 1/2 valvæ latitudine.

_Hab._--In Australiâ.

3. _Acasta cyathus_, Darwin. ('Balanidæ,' p. 312, Tab. 9, fig. 3.)

A. parietibus carino-lateralibus ferè 1/4 parietum lateralium latitudine: radiis latioribus quam parietes: basi pæne planâ, exiguâ: tergi calcare truncato, 1/2 valvæ latitudine.

_Hab._--In Madeirâ et Indiâ occid.

4. _Acasta undulata_, Darwin. ('Balanidæ,' p. 313, Tab. 9, fig. 4.)

A. testâ, ad speciem, ut in "A. spongites," sed majore: scuto externe striis longitudinalibus, sæpe binis, signato, sulcis intermediis latioribus: tergi calcare, pæne 1/2 valvæ latitudine.

_Foss._ in Angliâ. "Miocenâ Formatione."

5. _Acasta glans_, Lamarck. (Darwin, 'Balanidæ,' p. 314, Tab. 9, fig. 5.)

A. parietibus internè per-lævibus, marginibus lateralibus uniuscujusque testæ valvæ intùs prominentibus: basis acie rarò crenatâ, sed 6 dentibus introrsùs prominentibus instructâ: scuto longitudinaliter fortiter striato.

_Hab._--In Australiâ.

6. _Acasta lævigata_, J. E. Gray. (Darwin, 'Balanidæ,' p. 315, Tab. 9, fig. 6.)

A. parietibus intùs per-lævibus, marginibus lateralibus uniuscujusque testæ valvæ internùs prominentibus: basis acie fortiter crenatâ, et 6 dentibus introrsùs prominentibus instructâ: scuto aut longitudinaliter tenuiter striato aut lævi.

_Hab._--In Mari Rubro et Archipel. Philippino.

7. _Acasta fenestrata_, Darwin. ('Balanidæ,' p. 316, Tab. 9, fig. 7.)

A. testâ subrufâ, foraminibus magnis membranâ-tectis inter suturas suprà basin proximis, 6; parietibus carino-lateralibus 1/2 parietum lateralium latitudine: intùs, parietibus et basis acie lævibus: tergi cristâ articulari brevi prominente; calcare acuminato.

_Hab._--In Archipel. Philippino.

8. _Acasta purpurata_, Darwin. ('Balanidæ,' p. 318, Tab. 9, fig. 8.)

A. testâ obscurè cæruleo-purpureâ, foraminibus parvis, membrana-tectis inter suturas suprà basin proximis, 6: tergi cristâ articulari per-brevi prominente; calcare admodum lato rotundato.

_Hab._--In Sumatrâ et Archipel. Philippino.

9. _Acasta sporillus_, Darwin. ('Balanidæ,' p. 319, Tab. 9, fig. 9.)

A. testâ purpureo-fuscâ, parietibus intùs fortiter costatis et reticulatis: testæ valvis carino-lateralibus angustissimis, ad basin non extendentibus.

_Hab._--In Sooloo Insulis, in Archipelago Indico orient.

3. _Genus_--TETRACLITA.

1. _Tetraclita porosa_, Linn. (Darwin, 'Balanidæ,' p. 328, Tab. 10, fig. 1.)

T. radiis (si qui rarò adsunt) angustis; etiam suturis sæpe nullis: testâ abruptè conicâ, superficie plerumque corrosâ, stalactitiferam speciem exhibente.

_Hab._--In torridis et tepidis ubique maribus.

2. _Tetraclita serrata_, Darwin. ('Balanidæ,' p. 333, Tab. 10, fig. 2.)

T. testâ obscurè viridi-griseâ, costis longitudinalibus serratis angustis: radiis nullis: scuti cristis (articulari et adductoris) cavitatem usque ad apicem valvæ extendentem formantibus.

_Hab._--In Africâ merid.

3. _Tetraclita rosea_, Krauss. (Darwin, 'Balanidæ,' p. 335, Tab. 10, fig. 3.)

T. testâ sordidè albâ, subroseo tinctâ; parietibus è serie unicâ magnarum tubarum formatis: radiis plerumque angustis: tergi calcare sub-brevi, lato.

_Hab._--In Australiâ, et Africâ meridion.

4. _Tetraclita purpurascens_, W. Wood. (Darwin, 'Balanidæ,' p. 337, Tab. 11, fig. 1.)

T. testâ depressâ, pallidè purpureâ aut sordidè albâ, superficie longitudinaliter costatâ, aut corrosâ et granulatâ: radiis, aut etiam suturis, nullis, aut radiis planè formatis et latis, marginibus superioribus basi parallelibus: basi membranaceâ: scuto transversè elongato: tergo exiguo, calcare per-brevi, rotundato.

_Hab._--In Australiâ.

5. _Tetraclita costata_, Darwin. ('Balanidæ,' p. 339, Tab. 11, fig. 2.)

T. testâ depressâ sub-albâ, plerumque costis longitudinalibus admodùm prominentibus, 10: radiis latis, marginibus superioribus basi parallelis: basi calcareâ: scuto externè longitudinaliter striato: tergi calcare brevi rotundato.

_Hab._--In Archipel. Philippino.

6. _Tetraclita vitiata_, Darwin. ('Balanidæ,' p. 340, Tab. 11, fig. 3.)

T. testâ albâ, parte superiore plerumque roseo tinctâ; superficie irregulari; tubis parietalibus admodum irregularibus; radiis modicè latis, marginibus superioribus obliquis; alarum aciebus suturalibus percrassis crenatis: tergi calcare cum angulo basi-scutali non juncto; calcaris termino æquabiliter rotundato.

_Hab._--In Australiâ septentr. et orient. et Archipel. Philippino.

7. _Tetraclita cœrulescens_, Spengler. (Darwin, 'Balanidæ,' p. 342, Tab. 11, fig. 4.)

T. testæ parte superiore viridi-cæruleo tinctâ, longitudinaliter costatâ; radiis modice latis, marginibus superioribus obliquis: scuto adductoris cristâ exiguâ, articulari admodùm prominente; ambabus ita conjunctis ut cavitatem parvam subcylindricam efficiant: tergi calcare cum angulo basi-scutali non juncto.

_Hab._--In Archipel. Philippino et Oceano Pacifico.

8. _Tetraclita radiata_, De Blainville. (Darwin, 'Balanidæ,' p. 343, Tab. 11, fig. 5.)

T. testâ albâ costis longitudinalibus approximatis multis; radiis latis, marginibus superioribus leviter obliquis, intus porosis: tergi cristâ articulari suprà modum prominente; calcare cum angulo basi-scutali non juncto.

_Hab._--In Indiâ occid. et Australiâ: sæpe navigiis suffixa.

4. _Genus_--ELMINIUS.

1. _Elminius Kingii_, J. E. Gray. (Darwin, 'Balanidæ,' p. 348, Tab. 11, fig. 6.)

E. testâ lævi; griseâ aut sordidè albâ; radiis latis, marginibus et aciebus lævibus: scuto, sine adductoris cristâ: tergi calcare ab angulo basi-scutali distincto: scuto et tergo interdum inter se calcifactis.

_Hab._--In Americâ merid.

2. _Elminius modestus_, Darwin. ('Balanidæ,' p. 350, Tab. 12, fig. 1.)

E. testâ longitudinaliter plicatâ, subviridi aut albâ; radiis modicè latis, marginibus et aciebus lævibus: scuto sine adductoris cristâ: tergo angusto, calcare cum angulo basi-scutali confluente.

_Hab._--In Australiâ.

3. _Elminius plicatus_, J. E. Gray. (Darwin, 'Balanidæ,' p. 351, Tab. 12, fig. 2.)

E. testâ longitudinaliter profundè plicatâ, corrosâ, alicubi aurantiacâ; radiis per-angustis, aciebus sinuosis, leviter dentatis: scuto cum adductoris cristâ.

_Hab._--In Novâ Zealandiâ.

4. _Elminius simplex_, Darwin. ('Balanidæ,' p. 353, Tab. 12, fig. 3.)

E. testâ longitudinaliter costatâ, sordidè albâ; radiis angustissimis, marginibus et aciebus lævibus: scuto cum adductoris cristâ.

_Hab._--In Australiâ.

5. _Genus_--PYRGOMA.

1. _Pyrgoma Anglicum_, Leach. (Darwin, 'Balanidæ,' p. 360, Tab. 12, fig. 4.)

P. testâ abruptè conicâ, purpureo-rubrâ; orificio ovato, angusto; basi porosâ, plerumque è coralio exsertâ: scuto et tergo subtriangularibus.

_Hab._--In Magnâ Britanniâ et Europâ meridionali, et Insulis "Cape de Verde."

2. _Pyrgoma Stokesii_, Darwin. ('Balanidæ,' p. 361, Tab. 12, fig. 6.)

P. testâ modicè conicâ, pallidè purpureo-rubrâ; orificio ovato; basi non-porosâ, in coralium profunde conditâ: scuto et tergo subtriangularibus.

_Hab._--In Indiâ occid.

3. _Pyrgoma cancellatum_, Leach. (Darwin, 'Balanidæ,' p. 362, Tab. 12, fig. 5.)

P. testâ circumferentiâ plerumque lobatâ: scuto elongato, adductoris cristâ longè infrà marginem basalem descendente, et ad rostralem finem in acumen quadratum producto: tergi calcare valvæ partem superiorem longitudine quadruplo superante.

_Hab._--In Archip. Indico. orient. (?)

4. _Pyrgoma conjugatum_, Darwin. ('Balanidæ,' p. 364, Tab. 12, fig. 7.)

P. testâ pæne planâ, cristis approximatis radiantibus: scuto et tergo inter se sine suturâ calcifactis; scuto, adductoris cristâ infrà marginem basalem descendente, et ad terminum rostralem in acumen producto; tergi calcare superioris valvæ partis longitudinem ferè æquante.

_Hab._--In Mari Rubro.

5. _Pyrgoma grande_, G. B. Sowerby, jun. (Darwin, 'Balanidæ,' p. 365, Tab. 13, fig. 1.)

P. testâ modicè convexâ, pæne lævi: scuto et tergo inter se sine suturâ calcifactis; scuto limbo occludente parvo instructo, adductoris cristâ infrà marginem basalem descendente: tergo quadrato, calcare nullo.

_Hab._--In Archip. Indico orient.

6. _Pyrgoma milleporæ_, Darwin. ('Balanidæ,' p. 367, Tab. 13, fig. 2.)

P. testæ orificio angustè-ovato; vaginâ obscurè purpureâ: scuto multùm elongato: tergo triangulo, convexo, calcare nullo.

_Hab._--In Archip. Philippino.

7. _Pyrgoma dentatum_, Darwin. ('Balanidæ,' p. 369, Tab. 13, fig. 3.)

P. scuto multùm elongato, cum prominentiâ articulari dentiformi: tergo convexo, irregulariter triangulo, interdum cum calcare imperfecto, et in superficie internâ dente introrsùs prominente; scuto et tergo limbo occludente instructis.

_Hab._--In Mari Rubro.

8. _Pyrgoma crenatum_, G. B. Sowerby. (Darwin, 'Balanidæ,' p. 370. Tab. 13, fig. 4.)

P. scuto multùm elongato, adductoris cristâ infra marginem basalem reflexum descendente: tergi calcare lato depresso; scuto et tergo limbo occludente instructis.

_Hab._--In Archip. Ind. orient et Philippino.

9. _Pyrgoma monticulariæ_, J. E. Gray. (Darwin, 'Balanidæ,' p. 372. Tab. 13, fig. 5.)

P. testâ irregulari, margine exteriore aspero; orificio minuto rotundo: scuto et tergo multum elongatis, inter se sine suturâ calcifactis, limbo occludente lato instructis.

_Hab._--In Archip. Indico orient.

6. _Sub-Genus_--CREUSIA.

1. _Creusia spinulosa_, Leach, (Darwin, 'Balanidæ,' p. 376, Tab. 13, fig. 6, et Tab. 14, fig. 6.)

_Hab._--In Maribus torridis.

7. _Genus_--CHELONOBIA.

1. _Chelonobia testudinaria_, Linn. (Darwin, 'Balanidæ,' p. 392, Tab. 14, fig. 1 et fig. 5, Tab. 15, fig. 1).

Ch. testâ conicâ, depressâ, gravi; radiis subangustis, depressis plerumque utrinque scrobiculatis.

_Hab._--In tepidis et torridis ubique Maribus; testudinibus affixa.

2. _Chelonobia caretta_, Spengler. (Darwin, 'Balanidæ,' p. 394, Tab. 14, fig. 2.)

Ch. testâ globoso-convexâ, crassissimâ, gravissimâ; parte superiore tritâ, substriatâ; radiis aut non formatis aut admodum angustis; parietibus sine cavitatibus sursùm inter septa interrupta radiantia extendentibus.

_Hab._--In Africâ occid. et Australiâ septent.; testudinibus affixa.

3. _Chelonobia patula_, Ranzani. (Darwin, 'Balanidæ,' p. 396, Tab. 14, fig. 3).

Ch. testâ abruptè conicâ, admodum lævi et tenui; orificio magno, ferè dimidium diametri basalis testæ superante; radiis latis, lævibus, leviter depressis.

_Hab._--Mediterraneo; Africâ occid.; Indiâ occid.; Australiâ Crustaceis et molluscarum testis lævibus affixa.

[_Sectio_ ††.]

8. _Genus_--CORONULA.

1. _Coronula balænaris_, Linn. (Darwin, 'Balanidæ,' p. 415, Tab. 15, fig. 2, Tab. 16, fig. 3 et 5.)

B. testâ multùm depressâ, costis longitudinalibus planatis, aciebus earum simplicibus; orificio hexagono-rotundato; radiis testæ ipsius crassitudinem pænè æquantibus; valvis opercularibus, 4.

_Hab._--In Oceano meridionali.

2. _Coronula diadema_, Linn. (Darwin, 'Balanidæ,' p. 417, Tab. 15, fig. 3.)

C. testâ coroniformi, costis longitudinalibus convexis, aciebus earum crenatis; orificio hexagono; radiis modicè crassis, admodum latis; tergis nullis aut rudimentariis.

_Hab._--In Oceano septentrionali.

3. _Coronula reginæ_, Darwin. ('Balanidæ,' p. 419, Tab. 15, fig. 5.)

C. testâ globoso-conicâ aut depressâ, costis longitudinalibus multùm planatis, aciebus earum crenatis, superficie striatâ, granulatâ; orificio hexagono; radiis tenuibus 1/5 testæ valvæ crassitudinem non superantibus; tergis nullis.

_Hab._--In Oceano Pacifico.

4. _Coronula barbara_, Darwin. ('Balanidæ,' p. 421, Tab. 15, fig. 6).

C. testâ (probabiliter) coroniformi, costis longitudinalibus convexis, aciebus earum crenatis, superficie internâ et externâ cristis transversis asperâ; radiis modicè crassis; spatio inter radios et alas solidè impleto.

_Foss._--In Angliâ, "Red Crag Formatione."

9. _Genus_--PLATYLEPAS.

1. _Platylepas bissexlobata_, De Blainville. (Darwin, 'Balanidæ,' p. 428, Tab. 17, fig. 1.)

P. testâ lineis transversis incrementi conspicuis; parietibus porosis; vaginâ ad dimidium parietum vix descendente.

_Hab._--In Mediterraneo; Africâ occid.; Indiâ occid.; Australiâ septentrionali.

2. _Platylepas decorata_, Darwin. ('Balanidæ,' p. 429, Tab. 17, fig. 2.)

P. testâ costis longitudinalibus tenuibus, parte earum inferiore globulis minutis decoratâ; parietibus non porosis; membranâ basali pari cum testâ convexitate.

_Hab._--In Oceano Pacifico.

10. _Genus_--TUBICINELLA.

1. _Tubicinella trachealis_, Shaw. (Darwin, 'Balanidæ,' p. 431, Tab. 17, fig. 3).

_Hab._--In Oceano Pacifico meridionali.

11. _Genus_--XENOBALANUS.

1. _Xenobalanus globicipitis_, Steenstrup. (Darwin, 'Balanidæ,' p. 440, Tab. 17, fig. 4.)

_Hab._--In Oceano Atlantico septentrionali.

Sub-Fam. CHTHAMALINÆ.

12. _Genus_--CHTHAMALUS.

1. _Chthamalus stellatus_, Poli. (Darwin, 'Balanidæ,' p. 455, Tab. 18, fig. 1.)

Ch. testâ albâ aut griseâ, plerumque multùm corrosâ et punctâ; radiis (si qui adsunt) angustis, aciebus suturalibus tenuissimè crenatis; tergo, musculi depressoris cristis infrà marginem basalem vix dependentibus.

_Hab._--In Europâ; Americâ sept.; Braziliâ; Mari Rubro; Chinâ; Californiâ septent.

2. _Chthamalus antennatus_, Darwin. ('Balanidæ,' p. 460, Tab. 18, fig. 2.)

Ch. testâ conicâ, plerumque lævi; nisi profundè corrosâ, pallidè sordidè carneâ; suturis semper distinctis; radiis, si qui adsunt, aciebus suturalibus per-lævibus.

_Hab._--In Australiâ.

3. _Chthamalus cirratus_, Darwin. ('Balanidæ,' p. 461, Tab. 18, fig. 4.)

Ch. testâ albâ aut griseâ; vaginâ et valvis opercularibus membranâ fimbriatâ plerumque vestitis; tergo, angulo basi-carinali dependente et acuminato.

_Hab._--In Chiliâ, Peruviâ.

4. _Chthamalus fissus_, Darwin. ('Balanidæ,' p. 462, Tab. 18, fig. 6.)

Ch. testâ subfuscâ, plicatâ; orificio longitudine duplo majore quam latitudo; tergo triangulo, æquilaterali, marginibus basalibus et carinalibus leviter prominentibus.

_Hab._--In Californiâ.

5. _Chthamalus dentatus_, Krauss. (Darwin, 'Balanidæ,' p. 463, Tab. 18, fig. 3).

Ch. testâ sordidè albâ, aut subfuscâ; suturis, dentibus inter se concurrentibus formatis; tergi margine carinali prominente.

_Hab._--In Africâ.

6. _Chthamalus Hembeli_, Conrad. (Darwin, 'Balanidæ,' p. 465, Tab. 18, fig. 5.)

Ch. testâ obscurè rubro-purpureâ; suturis aut obliteratis aut dentibus inter se concurrentibus formatis; basi interdum per parietum inflectionem calcareâ factâ; scuto, sulcis duobus vel tribus ad mediam valvam deorsùm extendentibus.

_Hab._--In Californiâ.

7. _Chthamalus intertextus_, Darwin. ('Balanidæ,' p. 467, Tab. 19, fig. 1.)

Ch. testâ (si benè conservetur) violaceo-purpureâ; suturis aut obliteratis aut ex interplicatis laminis obliquis formatis; basi membranaceâ, sed cingente projecturâ ex parietum marginibus basalibus inflexis formatâ: scuto et tergo inter se prorsus calcifactis.

_Hab._--In Archip. Philippino.

8. _Chthamalus scabrosus_, Darwin. ('Balanidæ,' p. 468, Tab. 19, fig. 2.)

Ch. testâ (si benè conservetur) obscurè purpureo-fuscâ; suturis ex interplicatis laminis obliquis (sed raro benè) formatis; tergo, cum musculi depressoris fossâ profundâ angustâ, ad angulum basi-carinalem.

_Hab._--In Americæ merid. littore merid. et occid.

13. _Genus_--CHAMÆSIPHO.

1. _Chamæsipho columna_, Spengler. (Darwin, 'Balanidæ,' p. 470, Tab. 19, fig. 3.)

Ch. suturis, nisi in recenter natis, plerumque et internè et externè obliteratis; tergo, cum depressoris musculi fossis parvis.

_Hab._--In Australiâ.

2. _Chamæsipho scutelliformis_, Darwin. ('Balanidæ,' p. 472, Tab. 19, fig. 4.)

Ch. rostro per-exiguo, elongato, triangulo: testæ valvarum lateralium unâquæque cum foramine, et carinâ cum duobus similibus foraminibus; quæ 4 in columnas tubulares testaceas conducunt.

_Hab._--In Chinâ (?)

14. _Genus_--PACHYLASMA.

1. _Pachylasma giganteum_, Philippi. (Darwin, 'Balanidæ,' p. 477, Tab. 19, fig. 5.)

P. testâ et operculo sordide albis; testæ valvâ laterali et carino-laterali alis similibus instructâ.

_Hab._--In Mari Mediterraneo.

2. _Pachylasma aurantiacum_, Darwin. ('Balanidæ,' p. 480, Tab. 20, fig. 1.)

P. testâ aurantiaco tinctâ; ad speciem externam, quasi è 4 solùm testæ valvis formatâ, ideò quòd laterales, et carino-laterales valvæ utrinque obscurâ fissurâ solùm separantur.

_Hab._--In Australiâ.

15. _Genus_--OCTOMERIS.

1. _Octomeris angulosa_, G. B. Sowerby. (Darwin, 'Balanidæ,' p. 483, Tab. 20, fig. 2.)

O. testâ sordidè albâ, asperâ, solidâ; alis crassis, aciebus suturalibus obtusè crenatis.

_Hab._--In Africâ merid.

2. _Octomeris brunnea_, Darwin. ('Balanidæ,' p. 484, Tab. 20, fig. 3.)

O. testâ rubro-fuscâ depressâ, tenui, longitudinaliter sulcis tenuibus signatâ; tergi margine basali leviter in angulum flexâ.

_Hab._--In Archip. Philippino.

16. _Genus_--CATOPHRAGMUS.

1. _Catophragmus polymerus_, Darwin. ('Balanidæ,' p. 487, Tab. 20, fig. 4.)

C. basi membranaceâ: sine appendicibus caudalibus.

_Hab._--In Australiâ.

2. _Catophragmus imbricatus_, G. B. Sowerby. (Darwin, 'Balanidæ,' p. 490.)

C. basi calcareâ: cum appendicibus caudalibus.

_Hab._--In Indiâ occident.

2. Fam. VERRUCIDÆ.

1. _Genus_--VERRUCA.

1. _Verruca Strömia_, Müller. (Darwin, 'Balanidæ,' p. 518, Tab. 21, fig. 1.)

V. scuto mobili, cristâ articulari inferiore dimidiam brevis cristæ articularis superioris latitudinem non æquante: testâ plerumque longitudinaliter sulcatâ.

_Hab._--In Europâ; Mari Rubro.

2. _Verruca lævigata_, G. B. Sowerby. (Darwin, 'Balanidæ,' p. 520, Tab. 21, fig. 3.)

V. scuto mobili, cristâ articulari inferiore latiore quam brevis crista articularis superior; tergo mobili, latitudine majore quam altitudo, cristâ articulari superiore in terminum subacutum producto.

_Hab._--In Americâ merid.

3. _Verruca Spengleri_, Darwin. ('Balanidæ,' p. 521, Tab. 21, fig. 2.)

Scuto mobili, cum adductoris musculi cristâ acutâ, rectâ, mediali; scuto immobili non majore quam immobile tergum.

_Hab._--In Insulâ Madeirâ.

4. _Verruca nexa_, Darwin. ('Balanidæ,' p. 522, Tab. 21, fig. 5.)

V. testâ sub-rubrâ; scuto mobili cum cristis externis longitudinalibus fortiter prominentibus, præter cristas articulares; scuto immobili majore quam carina, adductoris musculi cristâ vel laminâ distinctâ nullâ.

_Hab._--In Indiâ occid.

5. _Verruca prisca_, Bosquet. (Darwin, 'Balanidæ,' p. 525, Tab. 21, fig. 4.)

V. testâ lævi; scuti mobilis cristâ articulari inferiore aliquanto latiore quam superior.

_Foss._--In Cretaceâ Formatione.

3. Fam. LEPADIDÆ.

1. _Genus_--LEPAS.

1. _Lepas anatifera_, Linn. (Darwin, 'Lepadidæ,' p. 73, Tab. 1, fig. 1, _var._)

L. valvis aut lævibus aut delicate striatis; è duobus scutis, dextro solùm dente interno umbonali instructo; pedunculi parte superiore fuscâ.

_Hab._--In Oceano, pæne ubique.