Page:The New International Encyclopædia 1st ed. v. 02.djvu/600

BARNACLE. bringing particles of food into the mantle cavity and down to the mouth. Thei-e is a liver or digestive gland connected with the stomach, but a large part of the trunk is occupied by the male reproductive organs. On the ventral side of the body is a strong muscle, by means of which the shell can be tightly closed. The nervous sys- tem consists of a brain and a ventral cord; but sense-organs, other than those of touch, seem to be wanting in all adults, though eyes arc present in the larvae. The Lepadidoe are very widely dis- tributed, but occur chiefly in the warmer seas. They are popularly known as goose-barnacles or goose-mussels, the latter name referring to the superficial resemblance they have to the moUusks known as mussels (q.v.). Although this resem- blance is very slight, barnacles were long classed as mollusks because of the presence of a shell. The number of species of goose-barnacles is not large ; but, owing to their becoming attached to the liottoms of ships, they are transported from one side of the globe to the other, so that the' same species sometimes occvirs in the harbors of Europe, Asia, Africa, Australia, and both coasts of America. Naturally, those which attach them- selves to rocks or other fixed bodies have a much more restricted range. None of the Lejjadidae are of large size; the body is usually under an inch in length, though the stalk is sometimes ten times as long. The colors are generally incon- spicuous — the stalk antl mantle ]iale brown, the calcareous plates pearly blue. None of the Lepa- didse have any economic vahie.

The rialanidw take their name from the Greek word /SaXavos, an acorn, in reference to the shape of the shell. In Great Britain these barnacles are usually called 'acorn-shells.' but the name is not in common use in the United States. The shell is much more fully developed than in the Lepadidie, and owing to this and the absence of a stalk, they difl'er superficially from that family to a marked degree. The mantle forms a truncated conical sac, attached by the base, and opening at the up- per or posterior end. This opening can be closed by four plates which correspond to the scuta and terga of the goose-barnacles. The mantle itself calcifies into six or more vertical plates, which are broadest at the base, and which can be more or less drawn together at the top, over the scuta and terga. The internal anatomy is very similar to that of the preceding family, but the ganglia of the ventral nei-ve-coi-d are fused into a single large ganglionic mass. The Balanida> are even more widely distributed than the Lepadidse, and are more abundant in the colder oceans. They often incrust rocks, wharf-piles, and other sub- merged timbers, and the bottoms of boats, and are frequently found on crabs, mollusks, and other marine animals. They are generally small, less than 2 inclies in height : but the largest known barnacle is Dalnnus p.iittacus, which is sometimes fl inches high and 4 inches in diame- ter. This species is of additional interest from the fact that large quantities arc gathered on the coast of Chile for food and export. Other species are also eaten, especially by the Chinese, and the Romans regarded some of the .Mediterranean forms as great delicacies. The flavor is said to be like that of other crustaceans, as shrimps, lob- sters, etc. The shells of the Bahinida? are very hard, and when clean are almost pure white. The Alnippifl(r. are a very small family of mi- nute species, which live in burrows in the shells of mollusks and some of the larger cirripeds. The mantle lines the burrow, and is attaclied at one side by a horny disk. The se.xes are separate and the females are much larger than the males, which are generally found living within the mantle cavity of tiie females, but it is not cer- tain that they remain there through life. The Proteolepadidce are a still smaller family. The species are minute, maggot-like animals, with no limbs, parasitic in other crustaceans. So degenerated is the adult female by its par- asitic life, that its body consists only of a sac containing the reproductive organs, attached to the crab by numerous fine root-like processes. On account of these, which have arisen from the head of the young, these animals are also known as Rhizocephala or 'root-headed' animals. The best-known genus is SacciiJina, which has long stood as the extreme example of the degenerating effect of a parasitic life. The members of these last tw-o families of barnacles would never be recognized as cirripeds at all from a study of their anatomy alone. But the study of their embryology' and the knowledge of their life his- tories have revealed clearly their ancestry and relationship; for in early life the larvip of both these families show the same essential characters as the larvse of other barnacles, and it is only after they have taken up their abode in their host that the degeneration becomes marked. In liacciilinfi, the males never become attached to a host, Imt remain in the larval condition through- out life, except for the development of the repro- ductive organs.

Barnacles have a special historical interest to every biologist, from the fact that the only ex- tensive systematic work in zoology done by Dar- win was done upon this group. The classical volumes entitled "monograplis' of living and fos- sil Cirripedia. by Charles Darwin, published by the Ray Society of London in 1851-54, will al- ways be invaluable to students of the Crustacea. Darwin spent eight years on this work, and it illustrates admirably his patience, thoroughness of investigation, and clearness of expression. An- other important work on barnacles is Part XXVIII. of the ChuUenger reports; Hoek, He- port on the Cirripedia Collected b;/ H.M.S. Chal- lenger (London, 1884).

BARNACLE, Lord Decimus Tite. The ex- tremely self-sufficient nobleman who. with his two sons, Clarence and Ferdinand, is in charge of the 'Circumlocution Office' (q.v.), in Dickens's Little Dorrit.

BAR'NACLE-EAT'ER. See Filefisii.

BARNACLE (prob. hcrnicle) GOOSE. A goose (Branta leucopsis), common in northern Europe and Cireenland. but rare in North Amer- ica. The name arose from the tallies of former days, which represented it as developing from a stalked or 'goose' barnacle, in size the barnacle-goose is smaller than the common wild goose, lieing only a little more than two feet long and wcigliing about five pounds. It is very pret- tily marked, having the forehead, cheeks, and throat white, the bill black, and a black stripe ex- tending from it to the eye: the crown of the head, neck, and upper part of the breast black ; the rest of the plumage, on the upper parts of the body chiefly ash-gray and black in undulating bars— on the lower parts white. The white forehead dis- tinguishes this goose from any American species,