The Jerboas are any of ten genera and 25 species of jumping rodents of the family Dipodidae, found primarily in the arid regions of Africa and Central Asia. Jerboas have short front legs and are about 15 centimetres long from head to rump. With their long hind limbs-about ten centimetres -they can cover up to 2.7 m in a single leap, using their long, sometimes tufted tail for balance, or as a prop when sitting. They are sandy above and white below, often with the tip of the tail black; some species have large, broad ears.
Jerboas burrow in soil or sand and feed on plants, seeds, and insects. They do not require free water, obtaining sufficient amounts in their food. Some species breed more than twice in one year, the average litter being three. The Egyptian jerboa, Dipus sagitta, is a well-known species that is often tamed. Research Jerboa
Sagitta is the arrow-worm genus of Phylum Chaetognatha. The largest species reaches a length of about ten centimetres, the commonest two and a half centimetres in length and has a transparent, glassy body. Research Sagitta
Constellations are the groups into which astronomers have divided the fixed stars, and which have received names for the convenience of description and reference. It is plain that the union of several stars into a constellation, to which the name of some animal, person, or inanimate object is given, must be entirely arbitrary, since the several points (the stars) may be united in a hundred different ways, just as imagination directs.
The grouping adopted by the Egyptians was accordingly modified by the Greeks, though they retained the Ram, the Bull, the Dog, etc; and the Greek constellations were again modified by the Romans, and again by the Arabians. At various times, also, Christianity has endeavoured to supplant the pagan system, the VenerableBede having given the names of the twelve apostles to the signs of the zodiac, and Judas Schillerius having, in 1627, applied Scripture names to all the constellations. Weigelius, a professor of Jena, even grouped the stars upon a heraldic basis, introducing the arms of all the princes of Europe among the constellations. The old constellations have, however, been for the most part retained.
Ptolemy enumerated forty-eight constellations, which are still called the Ptolemaean. They are the following: 1. The twelve signs of the zodiac. 2. Twenty-one constellations found in the northern hemisphere - the Great Bear (Ursa Major), the Little Bear (Ursa Minor), Perseus, the Dragon, Cepheus, Cassiopeia, Andromeda, Pegasus, Equulus (Horse's Head), the Triangle, the Waggoner (Auriga), Bootes, the Northern Crown (Corona Boredlis), Ophiuchus, the Serpent (Serpentarius), Hercules, the Arrow (Sagitta), the Lyre, the Swan (Cygnus), the Dolphin, the Eagle (Aquila). 3. Fifteen constellations in the southern hemisphere - Orion, the Whale (Cetus), Eridanus, the Hare (Lepus), the Great Dog (Canis Major), the Little Dog (Canis Minor), Hydra, the Cup (Crater), the Crow (Corvus), the Centaur, the Wolf (Lupus), the Altar (Ara), the Southern Fish (Piscis Australia), the Argo, the Southern Crown (Corona Australia). Others were subsequently added, this being especially rendered necessary by the increased navigation of the southern hemisphere, and now the different groups of stars have come to be associated with all sorts of animals and objects, including the Giraffe, the Fly, the Air-pump, the Compasses, etc.
The different stars of a constellation are marked by Greek letters, alpha denoting those of the first magnitude, beta,those of the second and so on. Stars of the sixth magnitude are the smallest visible to the naked eye. Several stars also have particular names. Research Constellation
Abbreviations
Research Sagitta
