A Monograph on the Sub-class Cirripedia · Charles Darwin
2. CATOPHRAGMUS IMBRICATUS.
CATOPHRAGMUS IMBRICATUS. _G. B. Sowerby._ Genera of Recent and Fossil Shells, Plate. _Basis calcareous: caudal appendages present._ _Hab._--Antigua, West Indies, attached to a _Tetraclita porosa_. As stated under the genus, this species is known from two specimens in the British Museum, one of which is full-sized, being three quarters of an inch in diameter, but is destitute of the outermost whorls, of the basis, opercular valves, and animal's body; the other is perfect, but very young, being barely two tenths of an inch in basal diameter. As far as the characters can be made out from these materials, I can perceive no difference from _C. polymerus_ in the shell, excepting that in the small specimen of _C. imbricatus_, there would appear to exist fewer whorls. The opercular valves are likewise closely similar: in the scuta, however, of the young specimen in the present species, the articular ridge seems to be a little broader, but this is so variable a character that no confidence can be placed in it: these valves, moreover, externally have a broad furrow along the middle, running from the apex to the basal margin, which is not the case with the scutum of _C. polymerus_; but then I have often seen, in young specimens of Balanus, a similar furrow, which is quite absent in full-grown specimens. When we come to the basis we find a good diagnostic character, for here it is calcareous: it is rather thin, solid, and white; towards the outside it is pitted with small cavities, corresponding with the small teeth on the basal edges of the compartments. The latter adhere firmly to the basis. The central internal surface is covered by an irregular network of imbedded cement-ducts, some of which bifurcate. From the description here given, it will be seen that any figure would have been superfluous, the last species having been so well illustrated.
_Mouth._--I can point out no difference, excepting that the palpi are here more oval or less truncated at their ends; and that the lower corner of the maxillæ seems to be more prominent. In the _Cirri_, the rami of the first and second pairs are nearly equal in length: none of the spines are coarsely pectinated. In the four posterior pairs of cirri, instead of a tuft of small spines on each segment between the pairs of main spines, there are only a few minute intermediate spines: the dorsal tufts are also here smaller, but are, as in the last species, composed of short thick, and longer thinner spines. _Caudal Appendages._--This is the only species of sessile cirripede, with the exception of the two species of Pachylasma, which possesses these organs: they are situated on each side of the anus in the usual position: they are minute, equalling in length only the lower segment of the pedicel of the sixth cirrus: in a specimen in which the rami of the sixth cirrus had eighteen or twenty segments, these appendages consisted of only three tapering segments, supporting a few thick spines. _Branchiæ._--I believe I discovered these, consisting of two minute pouches, placed at the carinal end of the sack: if this observation be correct, this species differs from _C. polymerus_ in the much smaller size of these organs.
REMARKS ON BRONN'S LIST OF FOSSIL BALANINÆ AND CHTHAMALINÆ. The following species of fossil Balanidæ are given in that most useful work, the 'Enumerator Palæontologicus' in Bronn's 'Gesichte der Natur:' it has appeared to me that a few words on each species, might hereafter save others the trouble of searching through several works. _Tubicinella maxima_ of Morren, said to have been found in the Chalk: this would have been a wonderful fact, considering that no true sessile cirripede has hitherto been found in this formation, and that it implies the existence of Cetacea at this period; but I have been informed that the fossil in question is not a Cirripede. _Diadema bifidum_ = Coronula bifida of Bronn, in his 'Italiens Tertiär-Gebilde' (1831), p. 126 (no Plate). Without a much fuller description I can form no judgment on this species. _Diadema vulgare_ is probably the _Coronula barbara_, a Crag fossil described by me. _Pyrgoma undata_, Michelotti, in 'Bull. Soc. Geolog.' tom. x, p. 141, a mere name without any description: probably it is a synonym of _Pyrgoma sulcatum_, Philippi, 'Enum. Mollusc. Siciliæ,' which is a synonym of _Pyrgoma Anglicum_ of the present work; found recent and fossil. _Acasta Montagui_ is probably the extinct _Acasta undulata_ described by me. _Chthamalus giganteus_ of Philippi, is the _Pachylasma giganteum_ of this work; found recent and fossil.
_Chthamalus stellatus_, said by Philippi to be found fossil in Sicily; such may be the case, but the littoral habits of the species do not render it very probable. _Balanus carbonarius_ of Petzholdt, found in the Carboniferous formation! but I have given my reasons, in my 'Monograph on the Fossil Lepadidæ,' p. 5, for disbelieving that this is a Balanus, or even a Cirripede. _Balanus ostrearum_ appears to be a mere name by Conrad, published by Morton in his 'Synopsis of the Organic Remains of the Cretaceous Group,' 1834, Appendix, p. 8. _Balanus peregrinus_ is briefly described and poorly figured, without the opercular valves, by Morton, in his 'Synopsis,' _ut supra_, p. 72, Pl. 10, fig. 5: this Eocene species apparently resembles the Eocene _B. unguiformis_ of Sowerby, described in this work; but quite indispensable details of structure for identification are not given. Another figure of this shell is given in the 'American Journal of Science' (N. S.), vol. i, Pl. 2, fig. 6. _Balanus circinnatus_, _communis_, and _pustula_, of Defrance, as well as all the other species named by him, are described so imperfectly, that the descriptions are of no value whatever, every description being applicable to every species: I must add, that the _B. communis_ is not the _B. communis_ of British authors, a name applied to several forms.
_Balanus Finchii_ is briefly described and figured, but without the opercular valves, by Isaac Lea, in his 'Contributions to Geology,' 1833, p. 211, Pl. 6, fig. 222. I do not think that I have seen this species. _Balanus Holgeri_, Geinitz, 'Grundriss der Versteinerungen,' tab. ix, fig. 19. No opercular valves are given; this species cannot be even approximately recognised. _Balanus proteus_, Conrad, 'Fossil Shells of Miocene Formation of U. States,' p. 77, Pl. 44 (in 'Journal Acad. Nat. Sc.,' Phil., vol. vii, p. 134). I cannot recognise this species; it resembles _B. porcatus_; but as the radii are rather narrow, and apparently with slightly oblique summits, it may be _B. concavus_; the opercular valves are not figured. _Balanus sagittata_ is merely a provisional name without any description, given in a paper on the Crag by S. Woodward, in the 'London and Edin. Philosoph. Magazine, Brewster, Taylor, and Phillips,' vol. vii, July-December, 1835, p. 354. _Balanus sublævis_, J. de C. Sowerby, in 'Geolog. Trans.,' 2d series, vol. v, Pl. 25, fig. 3. Plate extremely imperfect; description extremely short and useless; a species from India not to be recognised. _Balanus balanoides_; the species thus named by Ranzani, and found by Philippi in Sicily, certainly is not the true _Lepas balanoides_ of Linn., but may be _B. amphitrite_ of this work. In British collections of Crag specimens I have found the _B. dolosus_ (nov. spec.) thus named: I much doubt whether the truly littoral _B. balanoides_ of Linnæus has been found fossil.
_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.
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