Page:Encyclopædia Britannica, Ninth Edition, v. 9.djvu/366

352 FLY F L Y whether this sex is here actually dimorphic, or whether the one dress is a passing phase of the other, is at present undetermined. Some of the African species, of which many have been described, seem always to retain the rufous plumage, but the long tail-feathers serve to mark the males ; and the whole group deserves far more investigation than it has ever received, as it is likely to reveal facts of the highest importance in regard to the theory of " Sexual Selection." On the other groups of the Family there is not room to descant. A few are distinguished by the brilliant blue they exhibit, as Myiagra azurea, and others as Monarcha (or Arses) chrysomela by their golden-yellow. The Australian forms assigned to the Muscicapidce are very varied, and probably require much further scrutiny. Sisura inquieta, for instance, has some of the habits of a Water- Wagtail (Motacilla), and hence has received from the colonists the name of " Dishwasher," bestowed in many parts of England on its analogue ; and the many species of Rhipidura or Fantailed Flycatchers, which occur in various parts of the Australian Region, have manners still more singular turning over in the air, it is said, like a Tumbler Pigeon, as they catch their prey; but concerning the mode of life of the majority of the Muscicapidce, and especially of the numerous African forms, hardly anything is known. (A. N.) FLYING AND FLYING MACHINES. See FLIGHT. FLYING-FISH are of two different kinds. The one (Dactylopterus) belongs to the Gurnard family (Triglidai), and is more properly called Flying Gurnard ; the other (Exocoetiis) has been called Flying Herring, though more nearly allied to the Gar-pike than to the Herring. Some other fishes with long pectoral fins (Pterois) have been stated to be able to fly, but this has been proved to be incorrect. The Flying Gurnards are much less numerous than the Exocoeti with regard to individuals as well as species, there being only three or four species known of the former, whilst more than fifty have been described of the latter, which, besides, are found in numerous shoals of thousands. The Dactylopteri may be readily distinguished by a large bony head armed with spines, hard keeled scales, two dorsal fins, <fcc. The Exocoeti have thin, deciduous scales, FIG. 1. Dactylopterus volitans. only one dorsal fin, and the ventrals placed far backwards, below the middle of the body ; some have long barbels al the chin. In both kinds the pectoral fins are greatly pro longed and enlarged, modified into an organ of flight, anc in many species of Exocoetus the ventral fins are similar!) enlarged, and evidently assist in the aerial evolutions ol these fishes. Flying fishes are found in the tropical and sub tropical seas only, and it is a singular fact that the geogra phical distribution of the two kinds is nearly identical The literature on the subject of flying fishes is very ex tensive, and great diversity of opinion exists amonj observers as regards the mode and power of their flight but the most reliable ai-ree that the fishes do not leave the vater for the purpose of catching insects, and that they are inable to move their fins in the manner of a bat or bird, or o change voluntarily the direction of their flight, or to fly Beyond a very limited distance. The most recent inquiries are those of K. Mobius (Die Beweyungen der Fliegenden Fischedurch die Liift, Leip. 1878, Svo), the chief results of which may be summed up thus. Flying fish are more fre- FIG. 2. Exocoetus callopterus. quently observed in rough weather and in a disturbed sea than during cairns ; they dart out of the water when pursued by their enemies or frightened by an approaching vessel, but frequently also without any apparent cause, as is also observed in many other fishes ; and they rise without re gard to the direction of the wind or waves. The fins are kept quietly distended, without any motion, except an occasional vibration caused by the air whenever the surface of the wing is parallel with the current of the wind. Their flight is rapid, but gradually decreasing in velocity, greatly exceeding that of a ship going 10 miles an hour and a distance of 500 feet. Generally it is longer when the fishes fly against, than with or at an angle to, the wind. Any vertical or horizontal deviation from a straight line is not caused at the will of the fish, but by currents of the air ; thus they retain a horizontally straight course when flying with or against the wind, but are carried towards the right or left whenever the direction of the wind is at an angle with that of their flight. However, it sometimes happens that the fish during its flight immerses its caudal fin in the water, and by a stroke of its tail turns towards the right or left. In a calm the line of their flight is always also vertically straight or rather parabolic, like the course of a projectile, but it may become undulated in a rough sea, when they are flying against the course of the waves ; they then frequently overtop each wave, being carried over it by the pressure of the disturbed air. Flying fish often fall on board of vessels, but this never happens during a calm or from the lee side, but during a breeze only and from the weather side. In day time they avoid a ship, flying away from it, but during the night, when they arc unable to see, they frequently fly against the weatherboard, where they are caught by the current of the air, and carried upwards to a height of 20 feet above the surface of the water, whilst under ordinary circumstances they keep close to it. All these observations point clearly to the fact that any deflexion from a straight course is due to external cir cumstances, and not to voluntary action on the part of the fish. FLYING FOX, or more correctly Fox BAT, a name ap plied to a family of fruit-eating bats (PteropidaB), found only in the Eastern hemisphere, and there confined to the tropical regions and Australia. It comprises 9 genera and G5 species, a considerable proportion of which occur in the islands of the Malay Archipelago. They are also found throughout Africa, and extend northward and eastward to China and Japan, and southward to Tasmania. They are likewise included among the few indigenous mammals of the South Sea Islands, being found in Samoa and the Marianne Islands. The flying foxes are the largest of the bats, the kalong of Java (Pteropus edutis) measuring nearly a foot and a half in length, and having an expanse of wing-mem-