COQUETTE.

tail is long, and capable of wide spreading; the colors varied and brilliant, and the whole effect of the bird is peculiarly gem-like. See Plate of HUMMING-BIRDS and CROSS-FERTILIZATION.

COQUI, ko'kê (probably of West Indian origin). A West Indian tree-frog (Hylodes Martinicensis) remarkable for undergoing its whole metamorphosis within the egg. "The pairing takes place on land in the months of May and June, when the female lays about twenty eggs, which are enveloped in a foamy mass and glued onto a broad leaf, or hidden in the axillæ of iridaceous plants. The mother seems to remain in the neighborhood watching the eggs, which are large, measuring four to five millimeters in diameter pale and straw-colored. The embryo develops neither gills nor gill-openings, but a large, well-vascularized tail, by means of which, being immersed in the watery fluid contained within the egg, it seems to breathe. After twenty-one days the tadpole, having used up all the available yolk and fluid, and most of its own tail, bursts the egg-shell and hops away as a little frog." Consult Gadow, Cambridge Natural History, vol. viii. (London, 1901).

COQUILLA (ko-kwil'lå) NUT (Sp. coquillo, cocoanut). The fruit of a palm, Attalea funifera. It is exported from South America, being used to a considerable extent in America in the manufacture of buttons and in turning. It is also called vegetable ivory. See ATTALEA. COQUIMBITE. A hydrous sulphate of iron resembling Copiapite (q.v.) in composition and occurrence, but crystallizing in hexagonal forms. It is found near Copiapo, Chili.

COQUIMBO, kô-kem'bo. A seaport in the Province of Coquimbo, Chile, about ten miles south of La Serena, the capital of the province, with which it is connected by rail (Map: Chile, C 10). It has a good harbor, a lighthouse with a revolving light, a customs office, and exports chiefly copper ores. It is the residence of a United States consular agent. Pop., 1903, 8478.

COQUIMBO. See BURROWING OWL.

COQUINA, ko-ke nå (Sp., shellfish, from Lat. concha, Gk. kbyxn, konche, shell, Skt. sankha, conch-shell). A porous variety of limestone which occurs in Florida. It is made up of cemented fragments of shells and corals that have been cast about by the waves and accumulated in some sheltered basin of the sea-bottom. Coquina is extensively used for building - stone in Florida and the Bermudas.

CORACLE (Welsh corwgl, cwrwgl, coracle, from corwg, cwrwg, Ir. curachan, skiff). A boat of oval shape with a frame of wicker-work covered with hide or oiled cloth, which covering is removed when the boat is not in use. The ordinary coracle will carry comfortably only one

CORAL.

man, but it is so light that he can easily carry it on his back to a place where it may be safely deposited. See CURRACH. CORAIS, ko'râ', ADAMANTIOS. See CORAY, ADAMANTIOS.

CORAL (OF. coral, Lat. corallum, corallius, from Gk. Kopáλov, korallion, coral; of uncertain origin, possibly a loan-word from Heb. gōrāl, small stone). A calcareous or horny secretion or deposit of many kinds of polyps of the class Anthozoa, which assume various and often beautiful forms. Millepore 'coral' is produced by polyps of the class Hydrozoa. (See MILLEPORE.) The coral-producing polyps form colonies which increase by gemmation, young polyp-buds springing from the original polyp, sometimes indifferently from any part of its surface, sometimes only from its upper circumference, or from its

1. Diagrammatic cross-section of a coral: the black

part represents the stony outer wall (theca) and partitions (septa): the open lines, the fleshy lining and partitions (mesenteries). 2. Semi-diagrammatic view of a coral: a, a septum; b, a tentacle; c, position of the gullet; d, theca; e, mesenteric filaments; f, epitheca; g, basal plate.

base, and not separating from it, but remaining in the same spot, even when the original or parent polyp has ceased to exist, and producing The calcareous or horny buds in their turn. deposition begins when the polyp is single, adhering to a rock or other surface, on which the coral grows or is built up, the hard deposits of those of their progeny are attached. One layer former generations forming the base to which of the chambers, of which the greater number of corals are composed, occasionally surrounds an

other like the concentric circles in the wood of exogenous trees; one layer is sometimes deposited above another; the whole structure sometimes branches like a shrub, spreads like a fan, or assumes the form of a cup, a flower, or a

mushroom. Under the common name coral are included many species, also designated madrepores (q.v.), and some have received other names derived from peculiarities of their form and appearance, as brain coral, etc. This last forms into large rounded masses furrowed with winding depressions like the convolutions of a mam

malian brain or a meadow brook, hence its technical name is Meandrina. In the greater number of kinds, besides the plates which form and separate the polyp-cells, and which are variously arranged, there is a more solid internal or central part, formed by the additional deposition of matter at the bottom of each polyp-cell, or from the common living part in which the polyps are united. The calcareous framework is sometimes further strengthened by a greater or less mixture of horny animal matter with the purely calcareous substance.

Kinds of Corals.-Corals are roughly classed under two heads, the horny corals and the lime or stone corals. The former consist chiefly of a horny secretion from the polyps, which may include also separate particles of lime, while the stone corals consist almost wholly of lime firmly united in a solid mass. No sharp line can be drawn between these two groups, for all possible gradations can be found. The Antipatharia and Alcyonaria as a rule have a horny skeleton, while the millepores and madrepores are almost wholly limestone. The polyps of the common red or precious coral (Corallium rubrum) belong to the suborder Alcyonaria (q.v., for illustration); but the central axis in this and other corals forming the family Corallida is quite solid, and is produced in concentric layers by the living gelatinous substance which envelops it like the bark of a tree, and from which the polyps project like buds, or, when their tentacles are expanded, like little flowers. Another alcyonarian coral of more than usual interest is the 'organ-pipe' coral (Tubipora) in which no central axis fills in behind the polyps, but the chambers in which they live remain as open, elongated tubes, crowded together side by side to form a solid mass. Its polyps are violet or grass-green, but the coral itself is red or purplish. These corals are found in the Indian and Pacific oceans. Many of the madrepores have the whole calcareous framework covered, as in the Corallidæ, by a gelatinous living substance which unites all the polyps. The whole living part soon decomposes and disappears, when the coral is taken out of the water, in some species almost immediately running from the calcareous part as a watery slime.

Utilization. Red coral-so much admired for its fine color and susceptibility to a high polish, and much used for ornamental purposes-is chiefly obtained from the Mediterranean, in some parts of which extensive 'fisheries' are carried on. It is brought up from consider able depths by means of a sort of grappling apparatus dragged after a boat or boats, the pieces being broken from the bottom by beams of wood which are sunk by weights and then entangled among hemp. Red coral has a shrublike branching form and grows to the height of about one foot, with a thickness like that of the little finger. Much of the coral of the Mediterranean is exported to India, but red coral is also obtained in the Red Sea, the Persian Gulf, etc. Black coral (Antipathes), the axis of which is more solid, is still more highly prized. Coral was known to the ancients, and was used for ornamental purposes by the Gauls.

Reefs. The formation of coral reefs and islands is one of the most noteworthy results of the action of coral polyps. Many kinds of polyps are concerned in the building of a reef, but the

growth is mainly dependent on the stone corals. Reef-building corals only flourish in clean, fresh sea-water, which is not over 125 feet in depth and never is cooler than 68° F. They are consequently confined to the tropics and to shallow water, and never thrive near the mouths of rivers. Although reef-building corals are not found on the coast of the United States north of Florida, some species of coral occur much further north. Even on the coast of New England there is to be found quite commonly a true stone coral (Astrangia Dana), the polyps of which when expanded are large and very beautiful.

FOSSIL FORMS. Among the fossil corals only those belonging to the Anthozoa are of importance, those of the Hydromedusa either not appearing until the Mesozoic, and then but sparingly (for fossil Hydrocoralline and Tubularia, see CŒLENTERATA), or not being clearly recognized as to their systematic position and only provisionally referred to the Hydrozoa. (See STROMATOPORA and GRAPTOLITE.) The Anthozoa appear in the Cambrian rocks with the Archæocyathinæ, forms of peculiar structure and uncertain relationships. In the Upper Silurian period they have become the most important fossils, as well in number of individuals as in diversity of structure and importance as rock-building organisms. They continue thus throughout geologic times, and are hence of great importance to the paleontologist and geologist. As they are also objects of great beauty, they are much sought by collectors and dealers. Especially rich and famous are the fossil coral faunas of the Silurian of North America and Gotland; the Devonian of the Helderbergs of New York, the Falls of the Ohio, and the Rhenish provinces; the Jurassic formations of Middle Europe and the Tertiary beds of northern Italy.

The Anthozoa are divided by Haeckel into the sub-classes Tetracoralla, Hexacoralla, and Octocoralla, according to the number of their septa. which were considered to be multiples of these figures. The Tetracoralla comprise, together with the Tabulata, the Paleozoic corals; the Hexacoralla and Octocoralla, the Mesozoic and later forms. Recent investigations on the embryology of the Hexacoralla and thecal structure of the Tetracoralla (Dr. M. Ogilvie) seem to demon- • strate that these divisions are artificial, that the tetrameral system is only an ancestral feature strongly marked in certain of the old families (Cyathophyllidæ, Zaphrentidæ, Cyathaxonidæ), while hexameral symmetry is but one of many forms of radial symmetry. The Anthozoa are therefore at present divided into but two subclasses, according to Ray Lankester: the Aleyonaria or Octocoralla, and the Zoantharia. None of the fossil alcyonarians, which with doubtful forms do not appear till the Mesozoic, are of importance; the Paleozoic Heliolitida, which are referred with doubt to this sub-class, are quite abundant in the Silurian and Devonian rocks.

The sub-class Tabulatæ, of Milne-Edwards and Haime, comprising common and important Paleozoic genera, such as Favosites, Aulopora, Syringopora, Halysites, and Chætetes, which was long considered as a distinct sub-class characterized by the slight development of the septa and the presence of numerous tabulæ, has been broken up; it having been recognized that some families belong to the Octocoralla, others (Favositide, Syringoporidæ, Halysitidæ) exhibit close relationships to the Hexacoralla, and

now