Part 57

_B. costatus_ of Montagu, a synonym of _B. sulcatus_ of Bruguière, and of _B. porcatus_ of this work; found fossil and recent. This species was originally described by Linnæus under the name of _Lepas balanus_. But the fossil _Lepas balanus_ of Brocchi is a different species; if it be the same with the recent _Lepas balanus_ of Poli, then it is the _B. perforatus_ of the present work. Again, the _B. sulcatus_ of Bronn, in his 'Lethæa Geognostica' (tab. 36, fig. 14), is quite different from the _B. sulcatus_ of Bruguière (_i. e._, _B. porcatus_ of the present work), as is at once obvious from the oblique summits of the radii. Lastly, _B. tesselatus_ of Sowerby is a synonym of _B. porcatus_, _sulcatus_, _costatus_, and _Lepas balanus_.

_B. punctatus_ of Montagu is a synonym of _Chthamalus stellatus_, see remarks on that species: the name of _B. punctatus_ is often applied by British authors to varieties of _B. balanoides_, see remarks on that species.

_B. rugosus_ of Morris's 'Catalogue' is a synonym of _B. crenatus_; found recent and fossil.

_B. sulcatus_ of Bruguière, a synonym of _B. porcatus_; found recent and fossil: see remarks under _B. costatus_.

_B. tintinnabulum_ of Linn., found recent and fossil; but no trust whatever ought to be placed in the identifications of this species given in several works; thus the _Lepas tintinnabulum_ of Brocchi is distinct. The _B. crassus_ of Sowerby is the true _B. tintinnabulum_. The _B. fasciatus_ of Dujardin (perhaps only a MS. name) probably is also this species. The _B. crispatus_ is only a variety of _B. tintinnabulum_.

_B. dentiformis_, Defrance: see _B. circinnatus_.

_B. ornatus_, Münster, 'Beiträge zur Petrifact.,' B. 3, p. 29, tab. vi (1840). No opercular valves or details of structure of the several species of Balanus named by Münster, are given, and consequently none can be recognised with certainty.

_B. concavus_ of Bronn, fully described in this work, with the synonyms given; recent and fossil.

_B. crassus_ of Sowerby, a synonym for _B. tintinnabulum_.

_B. latiradiatus_, Münster, probably a synonym of _B. tintinnabulum_, see remarks under _B. ornatus_.

_B. pectinarius_, Bronn ('Italiens Tertiär-Gebilde,' p. 128), does not appear to me fully enough described to be recognised.

_B. pictus_ of Münster, possibly a synonym of _B. amphitrite_: see remarks under _B. ornatus_ and _balanoides_.

_B. plicarius_, Bronn: see remarks under _B. pectinarius_.

_B. porosus_ of Hausman (according to Münster of Blumenbach). I cannot recognise this species in Münster's 'Beiträge.'

_B. pustularis_ of Lamarck, 'Animaux sans Vertèbres.' Scarcely one of the fossil species of Balanus, described by Lamarck, can be recognised; the descriptions are extremely imperfect. There is a figure of _B. pustularis_ in Münster's 'Beiträge,' which makes me think that this may be a synonym of _B. concavus_ of Bronn.

_B. pyramidalis_, Münster: see remarks under _B. ornatus_.

_B. rhomboicus_, Bronn: see remarks under _B. plicarius_.

_B. squamosus_, Defrance: see remarks under _B. circinnatus_.

_B. stellaris_, Bronn ('Lethæa Geognostica,' tab. 36, fig. 13). To this species, _Lepas stellaris_ (I presume a misprint for _stellata_) of Poli, is given as a synonym; but the _Lepas stellata_ of Poli is a Chthamalus, and this certainly is not the case with _B. stellaris_. I have received two specimens from the Continent named _B. stellaris_, but they certainly differed from the form so called by Bronn, for in that, the parietes are said to be porose and the radii very narrow: these foreign specimens I have named _B. inclusus_. A species described by me as _B. corrugatus_, resembles in external appearance the _B. stellaris_ of Bronn, but it is mere labour in vain to attempt identifying Balani by their external characters.

_B. striatus_, Defrance: see remarks under _B. circinnatus_.

_B. tertiarius_, Risso, 'Hist. Nat. de l'Europe Merid.,' vol. iv. I cannot recognise this species.

_B. tesselatus_, Sowerby, a synonym of _B. porcatus_; recent and fossil: see remarks under _B. costatus_.

_B. zonarius_, Münster: see remarks under _B. ornatus_; possibly this is a synonym of _B. concavus_.

_B. amphimorphus_, Lamarck: see remarks under _B. pustularis_.

_B. crispatus_, _var._ of _B. tintinnabulum_.

_B. cylindraceus_, Lamarck. From Chenu's 'Illust. Conch.,' in which work Lamarck's original specimens are figured; it appears that this is the _B. psittacus_ of South America, where it is also found fossil, but assuredly Lamarck is quite in error when he states that a variety of this species occurs fossil near Turin. Bronn (in his 'Italiens Tertiär-Gebilde,' p. 127) gives as a synonym to the Turin fossil the _Lepas tintinnabulum_ of Brocchi (in the 'Conchologia Fossile Subapennina,' t. 2, p. 597), and this probably is correct; and I have hardly any doubt that the _Lepas tintinnabulum_ of Brocchi is the _B. concavus_ of Bronn described in the present work.

_B. perforatus_ of Bruguière is said by Philippi to be found in Sicily: see remarks under _B. tulipa_.

_B. semiplicatus_, Lamarck: see remarks under _B. pustularis_.

_B. tulipa_ of Müller is the _B. Hameri_ of this work, under which name full information on its geological history has been given. The _B. tulipa_ of Poli and Ranzani is the _B. tulipiformis_ of the present work; and this latter species is said by Philippi to occur fossil in Sicily. But there has been so much confusion in the identification of _B. tulipiformis_, _B. Hameri_, and _B. tintinnabulum_, and likewise of _B. perforatus_ (which by Poli was wrongly considered to be _L. balanus_, Linn.), that doubts must be entertained about which have been really found, until the Sicilian fossils are all carefully examined.

_B. ovularis_, Lamarck: see remarks under _B. pustularis_.

_B. Uddevallensis_, Linnæus, is probably a synonym of the _B. Hameri_ of this work and the _B. tulipa_ of Müller.

[A few other references may be added to those given by Bronn.]

_B. miser_, stated by Lamarck to be found fossil: see remarks under _B. pustularis_.

_B. patellaris_ of Lamarck, is stated by Marcel de Serres to be found fossil with several other species of Balanus; thus named without any description in the 'Annales des Scien. Phys. et Nat. de Lyon,' tom. i, p. 417.

_B. virgatus_, _delphinus_, and _crispus_, are names given by Defrance, with absolutely worthless descriptions.

_B. radiatus_ is too briefly described by Risso ('Hist. Nat. de l'Europe Merid.,' tom. iv, 1826), without a figure, to be recognised; it probably is not the _B. radiatus_ of Spengler, Wood, and other authors.

_B. goissopomo_, _lævis_, and _radiatus_, are mere names without any description, published in a Catalogue by F. Hoeninghaus, in the 'Jahrbuch für Mineral. Geog.,' &c., 1831, p. 155.

_B. humilis_. Conrad, in the 'American Journal of Science,' vol. ii (N. S.), p. 400, 1846, has given a short description, with a woodcut, of this species, from the upper Eocene of Florida. The opercular valves are not described, and I doubt whether the species could be recognised.

2. Family--VERRUCIDÆ.

_Cirripedia without a peduncle: scuta and terga, not furnished with depressor muscles, moveable only on one side, on the other side united immoveably with the rostrum and carina into an asymmetrical shell._

The one genus herein contained differs so considerably from all the others in the Order, in the extraordinary unequal development of the two sides of the shell, that I have instituted a Family for its reception. If compelled to place it in one of the foregoing families, I should with much hesitation rank it in the sub-family Chthamalinæ, rather than amongst the Lepadidæ; for it is destitute of a peduncle, and has a shell, though a very different one from that of any true sessile cirripede. In the interfolding sutures which may be considered as representing radii or alæ, in the basis being divided into concentric slips, and in the whole of the basis being attached to the supporting object, this same line of affinity is clearly manifested. On the other hand, in the general shape, manner of growth, and kind of articulation of the scutum and tergum, there is so close an approach to the Lepadidæ, that had I seen these very important valves separately, I should certainly have concluded that they had come from a Pollicipes, allied to certain Cretacean fossil species, as _P. fallax_ and _elegans_; it likewise, perhaps, deserves notice, that the upward growth of the rostrum, in _Verruca nexa_, is a peculiarity found only in the valves of the Lepadidæ. Verruca differs both from the Lepadidæ and Balanidæ in the whole shell or external covering, having no other muscle besides the adductor scutorum. In the characters derived from the animal's body, Verruca approaches both families; but in the absence of branchiæ, and in the great development of the caudal appendages, perhaps it comes rather the nearest to the Lepadidæ. Whatever affinity there is to the Balanidæ, it is much stronger to the sub-family Chthamalinæ than to the Balaninæ; though the non-bullate labrum, in three of the species, and the great dissimilarity of the third cirrus from the three posterior pairs, at first seems to indicate a closer relationship to the Balaninæ; but the labrum is never notched, as in the latter sub-family, and in _V. nexa_ it is bullate, and supports palpi of only small size. The dissimilarity, also, of the third pair of cirri, compared with the posterior pairs, is hardly greater than in _Chthamalus intertextus_ and _Chamæsipho columna_, members of the Chthamalinæ, though abnormal in this one respect. Perhaps even a special affinity is evinced between certain species of Chthamalus, as _C. intertextus_, and certain species of Verruca, as _V. nexa_, namely, in the interfolding sutures and in the very peculiar, inflected basal margin of the walls. Upon the whole, the affinities of the Verrucidæ are complex, and nearly equally divided between the two great families of Balanidæ and Lepadidæ, or sessile and pedunculated cirripedes.

_Genus_--VERRUCA. Pl. 21.

VERRUCA.[136] _Schumacher._ Essai d'un Nouveau Syst. Class., 1817.

CLYSIA. _Leach._ Journal de Physique, tom. 85, July, 1817; _Clisia_, Leach, Encyclop. Brit. Suppl., vol. 3, 1824; _Clitia_, G. B. Sowerby, Genera of Recent and Fossil Shells.

CREUSIA. _Lamarck._ Animaux sans Vertèbres, 1818.

OCHTHOSIA. _Ranzani._ Memoire di Storia Nat., 1820.

LEPAS ET BALANUS AUCTORUM.

[136] According to Bock, in the 'Naturforscher' of 1778, this term was used by Rumph for a Chelonobia, but as it was before the adoption of the binomial nomenclature, according to the Rules, it may be passed over, and does not interfere with the priority of Schumacher.

_Distribution_, Northern Europe, Mediterranean, Red Sea, Madeira, West Indies, Tierra del Fuego, Chile, Peru.

The shell in this genus is extremely unsymmetrical, not two of the six pieces of which it is composed quite resembling each other. At first it appeared hopelessly difficult to identify, in a homological sense, these six valves, with those of ordinary cirripedes, but the difficulty soon quite vanished. The operculum consists of two moveable valves on one side, namely, a scutum and tergum, but without any moveable valves on the opposed side: the scutum, though remarkable from being much smaller than the tergum, can be easily recognised by giving attachment to the animal's body and to the adductor scutorum muscle. The four other pieces are articulated together, and form the shell surrounding the sack, in which the animal's body is enclosed: of these, the two against which the moveable scutum and tergum shut, are smaller, differ greatly in shape, and are articulated together in a different manner from the remaining two pieces; from these facts alone there would be a strong presumption that they were of a different nature. The fixed valve, against which the scutum shuts, is either furnished with a remarkably prominent plate (_a_ in fig. 1 _c_, _s′_; compare this with _s′_ in the reversed shell in fig. 1 _e_), or is hollowed out, as in _V. nexa_, for the attachment of the adductor scutorum muscle. Thus it is rendered probable that this fixed valve is a modified scutum; but a surface of attachment for one end of the adductor muscle might, perhaps, have been developed on any other valve, or a scutum might have become fused with a lateral valve of the shell; the shell on this latter view being rendered in idea more symmetrical. But when a very young specimen is carefully examined, it is found that the moveable and fixed scutum, the moveable tergum and its opposed valve or fixed tergum, at the first period of calcification, resemble each other quite closely; but that, as each zone of shell is added, the differences become rapidly greater and greater: hence, it may be considered as directly proved, that the two fixed valves (S′ and T′ in all the figures in Pl. 21), which are opposed to the moveable valves of the operculum (S and T), consist of an extraordinarily modified scutum and tergum. It has been shown (p. 129), that at the period of the metamorphosis, the two scuta, the two terga, and the carina of the Lepadidæ, commence their growth, under the form of the so-called "primordial valves," and so differ from all the other valves when such occur: now, in two species of Verruca, I have found closely analogous primordial valves on the apices of both the moveable and fixed scutum and tergum (thus affording strong additional evidence that their nature has been rightly interpreted), and on one of the two remaining valves, namely, that at the posterior or carinal end of the shell. Hence, we may safely infer, that this latter valve, which, though very much more developed on one than on the other side, is so far medial as to curl round and cover the line of opening between the moveable and fixed tergum, is really a carina. The sixth valve differs only very slightly in shape from the carina, and is directly opposed to it; therefore, in accordance with all analogy, it must be the rostrum. Consequently, the shell in Verruca consists of a moveable scutum and tergum, a fixed scutum and tergum, a carina and rostrum, and, as we shall immediately see, a membranous basis--the basis being, as in all sessile cirripedes, the homologue of the peduncle in the Lepadidæ.

The moveable scutum and tergum stand at about right angles with the fixed pair; and as these latter form a part of the wall of the shell, which is always steep on this side, the moveable pair, which close the orifice, are nearly horizontal or parallel to the basis and surface of attachment. Hence, the animal's body, which is attached between the two scuta, but nearest to the moveable scutum, also, lies nearly parallel to the surface of attachment; and I was consequently at first led to suspect that the basal membrane was one side of the shell in a modified condition; but the presence of the prehensile antennæ of the pupa in nearly the middle of this membrane, and the sheet of cement-tissue on its under side, demonstrate that this membrane, though lying on one side of the animal, is the true basis. To make all the parts in Verruca hold the same position as in other cirripedes, relatively to the surface of attachment, we must develope the carina and rostrum equally on both sides of the true longitudinal axis of the shell, and insert the newly-developed portion between the basis and the fixed scutum and tergum, reducing the latter in size, and tilting a little up the moveable scutum and tergum; and by this means the animal's body would be turned, so that its dorso-ventral longitudinal plane would stand at right angles to the basal membrane.

Extraordinarily great as is the difference between the right and left sides of the whole shell, yet in all the species it seems to be entirely a matter of chance whether it be the right scutum and tergum with the right side of the rostrum and carina, or the left scutum and tergum with the left side of the rostrum and carina, which become abnormally developed. Nor does there seem to be any relation between the side of the operculum to be attached, whether right or left, and the nature of the surface of attachment; for I have seen many specimens adhering to perfectly level surfaces, and to quite cylindrical branches of Laminariæ; and in these cases, however the larva might attach itself, there could be nothing to favour the development of one side more than the other. Although the attached scuta and terga are larger than the moveable pair, yet, owing to the small development of the carina and rostrum on the attached side, the upper or unattached side must be considered as the most developed. In this respect, and in the circumstance of either right or left side being modified, we are reminded of the structure of _Pœcilasma Kæmpferi_ (described in my former volume on the Lepadidæ), in which the valves on the side of the capitulum, nearest to the crab's body, to which the specimens were attached, were somewhat less developed than those on the opposite side. I may add, that in ordinary Crustaceans, as I am informed by Professor Bell, the unequal development of the thoracic limbs seems quite capriciously to affect either the left or right side of the body.

_General Appearance of the Shell._--The shell is in most cases much depressed and irregularly circular; the side formed by the fixed scutum and tergum is always steeper than the other side: the colour is white or pale brownish, and in _V. nexa_ pale red. The surface is naked. The size is small, rarely exceeding a quarter of an inch in diameter, and the whole shell often appears like a mere scale on the surface of attachment. The most remarkable feature in the external aspect is due to the suture between the rostrum and carina, which is formed by oblique, interlocking plates or folds; as all these plates continue to be added to at their extremities during growth, the upper plates become longer than the lower ones; and the plates on both sides of the suture together form a triangular area, with the broad end uppermost, somewhat like the radius of a sessile cirripede: they act, also, like a radius, for their growth serves to separate these two valves, and so adds to the diameter of the shell. The suture between the rostrum and fixed scutum and that between the carina and fixed tergum are nearly of the same nature, but the former is more conspicuous than the latter; neither are so conspicuous as that between the carina and rostrum: accordingly as the right or left scutum and tergum are moveable, so the suture, second in plainness, (see Pl. 21, fig. 1 _a_, and 1 _d_,) is placed to the left or right hand. The fourth suture, between the fixed scutum and tergum, as viewed externally, is straight, and so very obscure that it has been overlooked by some authors, and the shell described as consisting of only three nearly equal pieces, for the fixed scutum and tergum together are about equal in size to the carina or rostrum. The orifice approaches more nearly to an unequal-sided triangle, with the apex broadly truncated, than to any other figure. The operculum fits with remarkable closeness, and is surrounded by a slight rim, formed by the edges of the four other valves.

_Moveable Scutum and Tergum._--The scutum (S in 1 _b_ and 5) is narrow and very small, barely equalling half the size of the tergum, and therefore proportionally much smaller than in any other cirripede; in a very young shell, however, (of _V. Strömia_) less than a pin's head in size, the scutum equalled the tergum in size. The valve is remarkably thick; it is generally depressed down the middle; but in _V. nexa_ this part is longitudinally ribbed. The occludent margin is curved. On the tergal margin there are two articular ridges (with a deepish furrow between them), of which the upper one (′ in S, in fig. 1 _b_, and 5) extends from the apex about half-way down the valve; and the other, or lower articular ridge (′′ in S), generally runs down nearly to the basal margin: an angle, running from the apex to the basi-tergal corner of the valve, appears like a third articular ridge, but cannot properly be considered such. The above two articular ridges interfold with analogous ones on the scutal margin of the tergum, and so lock the valves together. On the under side (fig. 1 _f_), the surface is bounded along the occludent margin by a slight rim: there is generally a very slight depression for the adductor muscle; but in _V. Spengleri_ there is a straight, short, sharp (Pl. 21, fig. 2), prominent adductor ridge.

The _moveable tergum_ is broad and rhomboidal. Externally a prominent axial ridge (′′′ in T, in fig. 1 _b_, &c.), which widens downwards, runs from the apex of the valve to the basal point, and there projecting slightly, causes the scutum to be indented; this indentation on the scutum appears like a third articular ridge, lying beneath (′′), S, in fig. 1 _b_, &c. Above the lower and axial ridge, on the scutal margin of the tergum, there is a middle articular ridge, which locks in, between the lower (′′) and upper articular ridges (′) of the scutum (S). Again above the middle ridge there is an upper and third articular ridge (′), which is either quite distinct, as in fig. 5, T, or more commonly is formed by the occludent margin of the valve, as in T, fig. 1 _b_. The broad extremity of this upper articular ridge is often produced into a slight projection, or shoulder, and this always underlies the scutum, of which the under and upper surface is indented or furrowed (see fig. 1 _f_), in order to receive this shoulder. The upper articular ridge of the scutum (′, S, 1 _b_) locks in between the upper articular ridge or occludent margin (′, T), and the middle ridge (′′, T) of the tergum.

Hence, altogether, there are three articular ridges on the scutal margin of the tergum, the occludent margin being generally counted as one; whereas, on the tergal margin of the scutum, there are only two ridges, though, as before noticed, an outer indentation, which is developed as a ridge in _V. nexa_ (fig. 5, S), might almost be counted as a third articular ridge.

I may here just remark, that the furrow between the two ridges on the tergal margin of the scutum, resembles the articular furrow in the scutum of the Balanidæ; but it may be doubted whether the resemblance be more than superficial, as this furrow, in the case of Balanidæ, receives the edge itself of the tergum, whereas here it receives only a ridge, proceeding from the apex of the tergum, to a nearly middle point on its scutal margin. Finally, I may add, that the tergum in this genus, in general shape, in growth (presently to be referred to), in the manner in which the upper scutal shoulder is overlapped by the scutum, and in the presence of the axial ridge, presents a very striking resemblance to certain old fossil species of Pollicipes, and to a limited extent to the living species of Lithotrya.

The scutum and tergum being interlocked, move together; they can be firmly shut by the contraction of the long adductor scutorum muscle. Their opening appears partly due to the elasticity of the membranous hinge (representing the opercular membrane), by which they are attached transversely, just beneath the summit of the carina and rostrum. No doubt the protrusion of the cirri effectively aids the act of opening. These valves are not capable (nor, of course, the other valves) of any other movement; for there are no muscles for such movements.