three usual monastic vows, they took a fourth, viz. not to sue for Church preferments, or to hold any post outside of their order without the Pope's special permission. In France and Aus- tria they were employed in the conversion of Protestants; but they have now, as a body, al- most fallen into oblivion. Only a few monaster- ies exist here and there in Italy and Austria. They were expelled from France in 1880.
BAR'NABY, Sir Nathaniel (1829—). An English naval architect. He was born at Chatham of a family long associated with the Royal Dockyard in that city. He was educated at Chatham, Sheerness, and Portsmouth, where, in 1848, he received the admiralty scholarship. He took part in planning nearly all the war vessels constructed between 1855 and 1885, and was one of the founders of the Institution of Naval Architecture (established 1860). Reintroduced the change from iron to steel in English shipbuilding in 1872. His principal publication is Abridgments of Specifications Relating to Shipbuilding, etc., from 1618 to the Present Time (1862).
BARNABY RUDGE. One of Dickens's novels (1841). It contains an account of the Gordon Riots in London, June 2-7, 1780. The principal character is a half-witted man, who gives the book its name. He is condemned to death as a rioter, but is finally reprieved.
BAR'NACLE. A popular name for the crustaceans of the order Cirripedia, notable for the fact that in their adult form they are always attached to some foreign object, such as ship-bottoms, wharf-piles, floating timbers, rocks, or even whales, or else live parasitically within other crustaceans. The ultimate origin of the word barnacle is unknown, but it was originally applied to the barnacle-goose of northern Europe, and its transfer to these crustaceans was due to the fables formerly current in regard to the reproduction of the bird. (See Barnacle Goose.) Considering the popular ignorance, both of the breeding habits of the geese and of the structure of barnacles, it is not extraordinary that the absurd tales in vogue should have found credence, the crustaceans be regarded as the young of the birds, and the name be transferred to them. Goose-barnacles (Lepas) were thus the first cirripeds to which the name was applied, and in Great Britain it is even now restricted to them and to similar stalked forms. Elsewhere, however, the name barnacle is now used for the sessile forms also, and even more broadly as the English term for all cirripeds.
Structure. Barnacles may be broadly defined as attached or parasitic Crustacea, with an indis- tinctly segmented body, surrounded by a mantle, which generally calcifies and forms more or less of a shell or ease. As they are attached by the head end, the first pair of antenna? (adhering organs) are very minute, and the second pair are reduced. There are generally six pairs (less fre- <|Ucntly throe or four) of long, biramons. tendril- like feet, though in parasitic forms these are wanting. There are no heart and no blood-vessels, and gills and other organs of respiration are therefore naturally wanting. Barnacles are gen- erally hermaphroditic, but in some species dwarf males occur, living in the mantle cavity of the normal individuals. In a few species the sexes are .separate and dimorphic. In their develop-
ment, barnacles undergo a most remarkable and very characteristic nietamorpliosis. The eggs hatch as minute. s(unewhat triangular larvse. with three pair of limbs, and a projecting hoi'u or process on each side anteriorly. On the Under side of the head is a prominent" upper lip. This larva sheds its skin several times as it grows, and finally appears as a larger, but still actively swimming creature, provided with a bivalve shell, like that of a clam. The body is segmented and there are six pairs of biramous feet. The antennie are modified to serve as organs of ad- hesion, and a 'cement' gland is formed and open.s in their second joint. This larva attaches itself by these antennæ, and after a resting or pupa stage, becomes transformed into the adult barna- cle, as a caterpillar changes into a butterfly. There is this important difference between the two proc- esses, however, that a butterfly does not grow, its size being no greater at death than when hatched, while barnacles continue to grow throughout life.
Classification. Barnacles are classified upon the manner of life and the method of attach- ment. The order Cirripedia is divided into five families, as follows:
(1) Lepadidæ, having the head end elongated to form a flexible stalk.
(2) Balanidæ, without a stalk, but having the body surrounded by a ring of calcareous plates.
(3) Aleippidæ, without stalk, or ring of, plates, only three or four pairs of feet.
(4) Proteolepadidæ, without stalk, plates, or feet.
(5) Kentrogonidæ, without stalk, plates, feet, mouth, or digestive system.
The last three of these families are parasitic, and their reduced structure is directly traceable to their mode of life. The anatomy and natural history of barnacles can be most clearly stated by treating each family separately, though it may be said once for ail that all barnacles are marine, except a single brackish-water species of Balanus.
The Lepadidæ take their name from the Greek word Afirds, a limpet, probably with reference to their being attached forms. The head end is more or less elongated to fonn the stalk by which the animal is attached. This stalk is fleshy, but tough and flexible; its length varies greatly, up to 10 or 12 inches. Within it are contained the cement gland, with its duct opening at the tip, and, near the base, the ovary, with oviduct open- ing above in the mantle cavity. The oral portion of the head, the trunk, and the appendages are contained within the mantle, which forms a lat- erally flattened sac, opening by a slit-like aper- ture at the upjier or outer end, on the ventral side. The mantle is chitinous, but contains, de- posited in its w-all, the plates of lime which com- pose the shell. There are five of the.se plates, a median unpaired one (the carina) on the dorsal side, an anterior one on each side (scuta), and a posterior one to each side (terga). There may also be small accessory plates on each side. The animal is so placed within the mantle that the mouth opens on the upper side of the attached end, the trunk curving backward and upward, and bearing the curious tendril-like feet on the ventral side. These feet are thus above the mouth, and in life project more or less freely from the opening of the shell; they are very flexible, and by their movements are continually
