RASTRITES, in paleontology, a genus of Graptolites or Rhabdophora. The potypary consists of a slender axial tube, having on one side a row of cellules, or hydrothecw, separate and not overlap ping. The typical species is R. pere grinus, which, with R. triangulatus, is found in the S. of Scotland. Etheridge makes a zone of R. peregrines in the Up per Birkhill or Gray Shale group of the Lower Llandovery. Found also in Bo hernia (where it is said to extend to the Upper Silurian), in Saxony, etc.
RAT, in zoology, a name popularly applied to the larger murines, but more strictly applicable to two species, the English black rat (Mus rattus), and the brown, or Norway rat (M. decumanus). The former is a small, lightly built animal, about seven inches long, with a slender head, large ears, and a thin scaly tail longer than the body. In tem perate climates the color is a bluish black lighter on the belly. The species is represented in warmer climates by the Alexandrian rat (M. alexandrines, better known as M. rattus rufescens), with a gity or reddish back, and white under-surface. By later naturalists it is considered as only a variety. The albino and pied rats, kept as pets, also belong to this species, which had its home in India and penetrated thence to almost every part of the world, driving out the native rats, and to be, in its turn exter minated by the brown rat (probably a native of China, where a similar spe cies, M. humiliatus, is still found). The brown rat is much more heavily built than the black rat, grayish-brown above and white beneath; ears, feet, and tail flesh-colored. Melanism often occurs, but such animals may be readily dis tinguished by ordinary specific differ ences from the true black rat. Length
of head and body eight or nine inches long, tail shorter. Both the species are omnivorous, predaceous, and extremely fecund, breeding four or five times in the year, the female producing from 4 to 10 blind, naked young, which breed in their turn at about six months old. M. fuscipes is the brown-footed rat of Australia; Nesokia bandieota, the bandicoot, or pig rat; and N. bengalen sis, the Indian field rat. Figuratively: (1) One who deserts his party (espe cially in politics), as rats are said to forsake a falling house or a doomed ship.
(2) A workman who takes work for less than the regular wages current in the trade; also a workman who takes employment at an establishment where the regular hands have struck; a term of opprobrium applied to non-union men by members of trades unions; specifically to non-union printers.
RATA (Metrosideros robusta), a New Zealand tree related to various species of ironwood. The seed is believed to be swallowed by a caterpillar, and to sprout in its interior, the fostering grub being of course killed. The tree begins life as a climber, attached to other forest trees, and attains a height of 150 feet; but when it has killed the supporting stem the rata is able to sustain its own weight and to grow on as an independent tree, attaining ultimately a height of nearly 200 feet. The wood is very hard, formerly much used for making clubs, and is valuable for shipbuilding.