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LEFT ABMADA 255 ABMATXJIIE expanded at the lower end, where it forms part of the wrist-joint. The mus- cles of the upper arm are either flexors or extensors, the former serving to bend the arm, the latter to straighten it by means of the elbow-joint. The main flex- or is the biceps, the large muscle which may be seen standing out in front of the arm when a weight is raised. The chief opposing muscle of the biceps is the tri- ceps. The muscles of the fore-arm are, besides flexors and extensors, pronators and supinators, the former turning the hand palm downward, the latter turning it upward. The same fundamental plan of structure exists in the limbs of all ver- tebrate animals. ARMADA, a fleet of armed ships; a squadron; particularly applied to that great naval armament, which was called the Invincible Armada, fitted out in 1588, by Philip II., against Queen Eliza- beth. It consisted of 129 ships, carrying about 20,000 soldiers and 8,000 sailors. The loss of the Marquis of Santa Cruz, their admiral, and a violent tempest, the day after they sailed, retarded for some time the operations of the Spaniards. They arrived on the coast of the Nether- lands in July, were thrown into disorder by a stratagem of Lord Howard, and in this situation were attacked with such impetuosity that it became necessary to attempt to return. Contrary winds obliged the Spanish admiral, the Duke of Medina Sidonia, to make the circuit of Great Britain with the wreck of this magnificent armament. In passing the Orkneys, it was attacked by a violent storm, and only a feeble remnant re- turned to Spain. ARMADILLO, the Spanish-American name now imported into English, of va- rious mammalia belonging to the order edentata, the family dasypodidse, and its typical genus dasypus. The name arma- dillo, implying that they are in armor, is applied to these animals because the upper part of their body is covered with large, strong scales or plates, forming a helmet for their head, a buckler for their shoulders, transverse bands for their back, and in some species a series of rings for the protection of their tail. The fore feet are admirably adapted for dig- ging, and the animal, when it sees dan- ger, can extemporize a hole and vanish into it with wonderful rapidity. If ac- tually captured, it rolls itself into a ball, withdrawing its head and feet under its strong armor. There are several species — such as the great armadillo, or tatu (dasypus gigas), the three-banded ar- madillo, or apara (D. apar), the six- banded armadillo (D. sexcinctus), and the hairy armadillo (D. villostis). They feed chiefly on ants and other insects ARMADILLO and worms, and are peculiar to South America. It is also the name of a genus of crus- taceans belonging to the order isopoda, and the family oniscidx, the type of which is the well-known wood-louse. It is so called partly from its being covered with a certain feeble kind of armor; but chiefly from its rolling itself up into a ball after the fashion of the South Amer- ican mammalian armadillos. ARMAGEDDON (-ged'don), the great battlefield of the Old Testament, where the chief conflicts took place between the Israelites and their enemies — the table- land of Esdraelon in Galilee and Samaria, in the center of which stood the town Megiddo, on the site of the modern Lej- jun; used figuratively in the Apocalypse to signify the place of "the battle of the great day of God." ARMAGH (ar-ma'), a city, and capi- ital of Armagh co., Ireland; and the archiepiscopal seat of the Primate of all Ireland; 70 miles N. W. of Dublin. It is said to have been founded by St. Patrick, A. D. 450. Pop. about 7,000. ARMATURE, armor worn for the de- fense of the body, or, more frequently, the armor in which some animals are enveloped for their protection against their natural foes. In magnetism, the armatures, called also the keepers, of a magnetic bar are pieces of soft iron placed in contact with its poles. These, by being acted on in- ductively, become magnets, and, reacting in their turn, not merely preserve, but even increase, the magnetism of the original bar. Magnets thus provided are said to be armed. Sometimes an arma- ture is made of steel and is permanently magnetized. Such an armature is termed a polai'ized armature, and is used in various appliances, magneto generators, telegraphic instruments, etc. In dyn- amic electricity, the armature is the shaft or central revolving arm of an