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OPERA BOITFFE 29 Charles Cadman (1918), and "The Le- gend" by J. C. Breil (1919). OPERA BOUFFE, a farcical form of opera buff a in which the characters, sub- ject matter, and music is intended to bur- lesque the more serious style of opera. Offenbach was the creator as well as the chief master in this art. The comic operas of Gilbert and Sullivan, both in the character of the music and the libretti, stand by themselves. OPERA GLASS, a binocular telescope of the kind invented by Galileo. It has a plano-concave or double concave eye glass, so that the image is not inverted and little light is lost, thus securing great distinctness. OPHIDIA, in zoology, snakes; an or- der of the class Reptilia, which is placed by Professor Huxley in his division Sauropsida. The body is always cylin- drical and without a bony exoskeleton. Vertebrae proccelous, with rudimentary transverse processes. They have no sternum, pectoral arch, forelimbs, or sacrum; nor as a rule are traces of hin- der limbs present, though they occa- sionally occur, e. g., in Python. Hooked conical teeth are always present, anchy- losed with the jaw. The order is pre- eminently tropical, the species rapidly diminishing as the distance from the equator increases, and wholly ceasing be- fore the Arctic or Antarctic Circle is reached. The classification is not fixed. Acording to Wallace, the order contains 25 families. There is another and natu- ral division into three sub-orders: (1) Thanatophidia (venomous snakes), with two groups, Proteroglyphia and Soleno- glyphia; (2) Coluhriformes (Innocuous colubriform snakes) ; and (3) Typhlo- pidse (blind snakes). OPHIR, an ancient country celebrated for gold. The ships of Solomon and Hiram, King of Tyre, brought 450 tal- ents of gold to Jerusalem, 1000 B. C. Its position has not been ascertained, and Arabia, India, and Africa are con- tended for by different authorities. Jo- sephus considers Malacca to be Ophir, and Sir Emerson Tennent supports this view. Purchas says Ceylon. But the discoveries made in 1868 of gold deposits on the E. coast of Africa, and the re- mains of the ancient workings, give addi- tional force to the ideas entertained by many that thereabouts was the locality of Ophir. OPHITE, green porphyry or serpen- tine, a metamorphic rock of a dusky- grreen color of different shades, sprinkled •with spots of a lighter green. It is a Vol. VII — Cyc OPIUM hydrous silicate of magnesia with alum- ina and iron. Called also ophiolite. OPHIUCHUS, in astronomy, Serpen- tarius, the Serpent-bearer, a constellation of the Northern Hemisphere. One of the ancient asterisms, having Hercules on the N., Scorpio on the S., and Ser- pens on the W. It has about 80 stars visible to the naked eye, the chief being Ras Alague. OPHIUROIDEA, an order of the Echi- nodermata, comprising star fishes known as brittle stars and sand stars. These animals have long slender- jointed arms, which may either be branched or simple, OPHTHALMIA, in pathology, a terra used to indicate the structural changes produced by proliferation and catarrhal inflammation, going on to the formation of pus in the mucous membrane of the eye, exhibiting various forms, catarrhal, pustular, purulent (in the new-born in- fant), gonorrhoeal, strumous, or scrofu- lous, and chronic. The chief symptoms are redness of the eye, chemosis, or swell- ing, discharge of fluid and pus, intoler- ance of light, and frequently, in severe cases, spasmodic closure of the eyelids. When the cornea is involved, destruction of the eye and permanent loss of sight — as in diphtheria and smallpox, or from sand, etc., as among the troops and na- tives in Egypt especially — is a common result. Treatment of the discharge by caustics and astringents is Imperatively called for. OPHTHALMOSCOPE, an instrument invented by Helmholtz, and described by him in 1851. It is used for the exam- ination of the inner structure of the eye- ball, and is composed of a small round mirror with a central perforation, which reflects the light of a lamp placed at the side of the eye. When the mirror only is used, the method is known as direct; when a convex lens is between the eye and the mirror it is indirect. OPISTHOBRANCHIATA, in zoology, an order of Gasteropoda. Shell rudi- mentary or wanting; branchiae arbores- cent or fasciculated, more or less com- pletely exposed on the back and sides toward the rear of the body. It con- tains two sections, Tectibranchiata and Nudibranchiata. OPIUM, in chemistry, the dried juice obtained from Papaver somniferuvi, ex- tensively cultivated in Asia _ Minor, Egypt, and India. An incision is made in the unripe capsules, the juice is left to dry over night, and then removed with a blunt knife. Opium is a complex substance containing morphine (3-15 per