Cirripedia

“ The order of the acalephæ (as the Beröe) which swims by action of cilia.
Cilia (L. cilium, an eyelash) . The microscopic hair-like bodies which cause, by their vibratile action, currents in the contiguous fluid, or a motion of the body to which they are attached.
Cirri (L. cirrus, a curl) . The curled filamentary appendages, as at the feet of the Barnacles.
Cirripedes, or Cirripedia (L. cirrus, a curl; pes, a foot) . A class of articulate animals having curled, jointed feet; sometimes written Cirrhipedia and Cirrhopoda.
Conchifera (L. concha, a shell; fero, I bear) . Shell-fish ”

“ In Ibla, the males are attached low down within the sack of the female; they may be said to consist of a mouth surmounted on a long peduncle, for there is no capitulum or general covering, and the whole thorax is in a rudimentary condition, the cirri being reduced to two distorted pairs. As these males certainly moult several times and grow a little, they must feed; and as they have no cirri fit for action, they must seize their food by the contortions of their peduncle, which we know homologically consists of the three first segments of the head. ”

“ The movements of the peduncle must, also, supply those of the probosciformed penis, almost invariably present with other Cirripedes, but here absent. If compelled to class these males without regard to the female, great difficulty would be experienced; we could hardly place in the family of the Lepadidæ, a Cirripede without a capitulum, and without cirri, those very organs which give their name to the class, and with a thorax reduced to the dimensions of a lower lip ”

“ I have as yet not entered in detail on the sex of the supporting Cirripede: in Cryptophialus, Alcippe, and in one species of Ibla, I was able to demonstrate in many specimens, that all the male organs, internal and external, were entirely absent; and consequently that these Cirripedes were exclusively female. In Scalpellum ornatum, also, there is no trace of external male organs (the state of the four dried specimens [Pg 29] not allowing the internal organs to be examined) , and there cannot be any reasonable doubt that this species likewise is exclusively female. ”

“ I may instance the antenniformed third pair of cirri in Chthamalus antennatus, the teeth on the posterior cirri in Acasta sulcata, the terga in Pyrgoma dentatum, the adductor ridge of the scuta in Pyrgoma cancellatum and in Creusia, and other such cases: hence it will not do to found a species on a slight, or sometimes even on a considerable difference, in any single point or organ. ”

“ Hancock, and a second burrowing genus, or rather family, obtained by me on the coast of South America. The third Order is highly singular, and differs as much from all other Cirripedes as does a Lernæa from other crustaceans; it has a suctorial mouth, but is destitute of an anus; it has [Pg 3] not any limbs, and is as plainly articulated as the larva of a fly; it is entirely naked, without valves, carapace, or capitulum, and is attached to the Cirripede, in the sack of which it is parasitic, by two distinct threads, terminating in the usual larval, prehensile antennæ. ”

“ All the five posterior pair of cirri resemble each other more closely than is usual. In D. Lowei, the segments of the posterior cirri bear the unusual number of eight pair of main spines.
Caudal Appendages.—Uni-articulate, spinose; in D. pellucida they are twice as long as the pedicels of the sixth cirrus, but I could not perceive in them any distinct articulations.
Distribution.—Attached to crabs at Madeira, and off Borneo; to sea-snakes in the Indian Ocean. The individuals of all the species appear to be rare. ”

“ In some specimens the radii extended down close to the basal cup, and only very minute clefts were left between the opposed edges of the parietes.
In the animal’s body the only noticeable character was, that on the anterior ramus of the fourth pair of cirri, some of the segments were furnished with very broad and thick, small, downwardly curved, teeth or hooks, like those described in certain varieties of A. sulcata; but they are here stronger and thicker. ”

“ In Ibla, the thorax is reduced to a mere flap, and only two pairs of cirri exist in a most useless and rudimentary state, but there is a well organised mouth, stomach, and anus. In the males of Scalpellum vulgare, ornatum, and rutilum there is no mouth or stomach, but there is a thorax with four pairs of minute, modified cirri, and a large abdominal lobe. Here, in the male Alcippe, all these negatives are united, we have no mouth, no stomach, no thorax, no cirri, no abdomen! The archetype crustacean consists of twenty-one segments ”

“ Within the sack the corium under the valves is tinted pale purple, and two very faint bands of the same colour can generally be distinguished running down the two sides of the peduncle. Body, coloured yellowish-white, with the upper segments of the pedicels of the cirri, tinted in front with purple.
Body, much flattened, the prosoma is very little developed; the mouth placed far from the adductor muscle, and is directed in a remarkable manner towards the ventral surface of the thorax: the first pair of cirri stands far separated from the second pair. ”

“ Cirri.—The five posterior pair are elongated, very little curled, with short pedicels; their segments are long, not at all protuberant in front, bearing five or six pairs of long, slightly serrated spines, with a very minute tuft of bristles between each pair, and with some short lateral spines on the inner side of each segment; on the fourth pair of cirri, these lateral spines are considerably developed; dorsal tufts consist of fine spines, with one much longer than the others. ”

“ The male Ibla must seize its prey, guided probably by its well-developed olfactory organs, through the movement of its long, flexible body, furnished with muscles, and with the mouth seated on the summit. We have already seen one instance of a Cirripede, the Anelasma, obtaining its food without the aid of cirri, by means of its probosciformed, flexible mouth. The eye can serve only to announce to the male when the female opens her valves, allowing occasionally some minute prey to enter. ”

“ Although in the dead state, the aperture of the capitulum seems to be always gaping, yet I have little doubt, that the living animal can fold the flexible membrane, like a mantle, round its thorax and cirri, and thus protect, though feebly compared with most Cirripedes, these organs. I suspect that the mouth is always exposed. ”

“ I have elsewhere stated my full belief that it is the ovigerous fræna which have been metamorphosed into the branchiæ of the Balanidæ. Most sessile cirripedes breed when very young; and I have every reason to believe that they breed several times in the year. The ova are ovate, and vary in length from 14/2000th of an inch in Chthamalus, to 19/2000th in some species of Balanus, in which this greater length was owing to a more elongated shape,—up to 25/2000th in some other species of Balanus. The ova are wonderfully numerous, especially in the genus Coronula. ”

“ The well-articulated thorax, by the aid of the muscles attached to every segment, can certainly be doubled up and contracted, [Pg 577] so that the cirri with their pedicels (coloured purple like the exposed labrum) can be wholly protruded out of the sack and shell-cavity. The three cirri no doubt can be separated a little from each other, both transversely and longitudinally; and according to analogy, the two rami of each cirrus can likewise be separated: there are, also, muscles for moving the two segments of the pedicel of each cirrus; and other muscles run up the many segments of the rami. ”

“ Generally the species are attached to living organic bodies, especially shells of Mollusca and of Cirripedes, to Gorgoniæ, and Laminariæ; less frequently to rocks. We shall immediately see that it has slight powers of excavation. This genus is geologically older than any true sessile cirripede or member of the Balanidæ: V. Strömia is found in the Glacial Deposits and in the Red and Coralline Crag of England: another species (in a state not to be identified) occurs in the ancient Tertiary formations of Patagonia ”

“ I will not compare the softer parts, such as the cirri and trophi, of the Lepadidæ with those of the Balanidæ, as my examination of this latter family is not fully completed: I will only remark, that there is a very close general resemblance, more especially with the sub-family Chthamalinæ.
Geographical Range; Habitats.—The Pedunculated Cirripedes extend over the whole world; and most of the individual species have large ranges, more especially, as might have been expected, those attached to floating objects ”

“ The outer maxillæ (like those at Pl. X, fig. 16) , are internally clothed continuously with spines. The olfactory orifices are not at all prominent.
Cirri.—The first pair is placed near the second pair, and is of considerable length; the second has the anterior ramus thicker than the posterior ramus, and the segments brush-like; the segments (Pl. X, fig. 26) of the four posterior cirri bear from four to six pair of long spines, with a row of small intermediate spines: in the posterior cirri of L. australis the lateral rim spines are much developed ”

“ This species is the commonest cirripede on the shores of the Falkland Islands: many of the specimens are there crowded together, and rendered elongated and cylindrical, with the walls very thin, and the sutures often obliterated; as the opercular membrane is very narrow, the opercular valves are much influenced both in their outline and in their [Pg 470] crests and articulations, by the varying form of the shell: I have even seen specimens with the scutum and tergum on one side twice as large as on the other side.
13. CHAMÆSIPHO—Nov. Genus. [132] Pl. 19. ”

“ The segments do not correspond even on opposite sides of the same individual, as may be seen in the two lower lines of the table. I believe that variability to this degree is very uncommon in other cirripedes, though, as stated in the Introduction, the number of the segments always increases with [Pg 332] the growth of the individual. The terminal segments in the longer rami of both the first and third cirrus are antenniformed,—being elongated, and of a different shape, with fewer bristles, compared with the basal segments of the same cirri. ”

“ It is clear that others have been equally perplexed; for that which is the anterior end in the eyes of one naturalist, is the posterior end in the eyes of another; so with the dorsal and ventral surfaces: one naturalist considers the peduncle of the Lepas as the abdomen; another considers it as a pair of metamorphosed, thoracic limbs, &c.! The probable position of the segments of the body of a mature Cirripede, in relation to the three anterior cephalic segments, or carapace, is shown in the diagram (Pl. 25, fig. 6) of the supposed position of the mature Proteolepas within its pupal envelopes. ”

“ I took home some specimens, and placing them in perfectly fresh water they continued for many hours expanding and retracting their cirri with perfect regularity and vigour. Here then we [Pg 253] have a Balanus capable of living in fresh water, and likewise in the saltest seas: even brackish water is a deadly poison to several, probably to most, species of the genus; but this, as we have seen, is not the case with the allied B. eburneus. The water, I may add, at Woolwich, on the Thames, whence I have received B. improvisus, must at times be very brackish. ”

“ The shelly layer forming the basis, in most of the species, is very thin, and is finely plicated owing to its edge folding between the ridges or septa that form the basal edges of the shell; this is very conspicuous in P. cancellatum. The basis is not permeated by pores, except in P. Anglicum. In some sessile cirripedes a cleft, covered only by membrane, may be observed all round between the lower edge of the shell and the basis; a cleft of this nature is rather conspicuous in P. crenatum, so that small portions of the septa on the internal surface of the walls can be seen from the outside. ”

“ I have already given my reasons for instituting and separating this genus from Lepas; as far as the capitulum is concerned, the differences between these genera certainly appear trivial; they consist in the carina not extending up between the terga, and in the lower end being either truncated, or produced into an imbedded disc: the terga have a single occludent margin. The included animal’s body differs in more important respects; for both mandibles and maxillæ are very distinct; the cirri of some of the species also differ ”

“ Maxillæ, with five steps: sometimes each step commences with a spine rather larger than the others; at the upper angle, there are two large unequal spines (neither pectinated,) with a third longer and thinner, seated a little below. Outer maxillæ (Pl. X, fig. 16) , simple.
Cirri, with twice as many segments in the sixth cirrus as in first; spines on the first and second cirri doubly serrated.
Colours (when alive) .—Capitulum and peduncle grey, with a tinge of blue, with six black bands, tinged with purplish brown. ”

“ In ordinary Crustaceans, the growth is periodical and sudden; a new and larger carapace, for instance, is formed under the old one, and after the exuviation of the latter, the new one soon hardens, and does not subsequently increase in size; so it is in the case of Cirripedes, with the membranes of the body, and even with certain parts, as the opercular membrane, of the external covering. But a Cirripede cannot, like a crab, crawl into some crevice and remain protected till its shell becomes hardened ”

“ In such cases, in some few recent specimens, and in all the large or even quarter-grown old tertiary specimens, but not in the quite young fossil specimens, a structure is presented, which I have not seen in any other Cirripede, namely, the basis (Pl. 4, fig. 2 a) is filled up for one third, or even for more than half its depth, by successive, separate, calcareous, transverse layers or septa. It would appear as if the basal cup had grown too large for the animal’s body, and so required filling up. The layers are thin and fragile; a single layer never stretches across the whole shell ”