R O S 



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RUG 



dver the body of the shell and a great 

 part of the spire. The most common 

 species is Rostellaria fissurella. Par- 

 kinson. 



Five species are enumerated by Dr. 

 Mantell as occurring in. the strata of 

 Sussex, above the Wealden, namely, R. 

 Sowerbii, R. Parkinson, R. carinata, 

 and R. calcarata : one species is found 

 with two processes, closely resembling 

 R. Pes Pelicani. Recent Rostellarije 

 are found in the Indian seas. 

 RO'STRATED. (rostratiis, Lat. beaked.) 



1. In botany, a term applied to plants 

 when the fruit has a beak-like process. 



2. In conchology, applied to shells having 

 a beak-like extension of the shell, in 

 which the canal is situated. 



RO'STRUM. (Lat.) A beak or bill; the 

 beak or bill of a bird. 



RO'TALITES. A genus of shells existing 

 only in a fossil state, and found at Grig- 

 non. Four species are described by La- 

 marck, namely, R. trochidiformis, R. 

 lenticulina, R. depressa, and R. discor- 

 bula. The shells of this genus are con- 

 vex, conical, spiral, multilocular, uni- 

 valves, slightly radiated beneath ; aperture 

 marginal, trigonal, and inclined down- 

 wards. 



ROTHE TODTE LiEGENDE. The name given 

 by the Germans to the lower beds of new 

 red sandstone. 



ROTI'FERA. The first order of the class 

 Infusoria. The researches of Ehrenberg 

 show that a group, formerly believed to 

 belong to the class of the most minute 

 animalcules, possess an organization ex- 

 tremely complex. They were charac- 

 terized as rotiferous animalcules, because 

 they have circles of vibratile cilia, which 

 appear like revolving wheels when they 

 are in rapid action, and by these hair- 

 like processes they were enabled to swim. 

 They float, attract their prey with these, 

 and thus get their food. They possess 

 an alimentary canal passing through the 

 body. They possess also muscular fas- 

 ciculi ; nervous ganglia ; and even a cere- 

 bral or supra-aesophageal ganglion. They 

 possess a vascular system pretty highly 

 developed, so that they are far removed 

 from the polygastrica, -Ehrenberg has 

 called them "rotatoria," but the term 

 rotifera is more generally used. They 

 are distinguished by their circles of cilia, 

 sometimes single, sometimes double, 

 which, through the microscope, appear 

 like revolving wheels. 



Lamarck is of opinion, from the obser- 

 tions of Du Trochet, that what are taken 

 for two or more wheels, are only one, bent 

 so as to form partial ones ; but in some 

 they certainly are distinct organs. The 

 object of the rapid gyration of this wheel 



or wheels is to create a vortex in the 

 water, whose centre is the mouth of the 

 animal ; a little charybdis bearing with it 

 all the animalcules or molecules that come 

 within its sphere of action. Prof. Grant. 

 Rev. W. Kirby. 



RO'TTEN STONE. Another name for Tri- 

 poli, in Barbary, whence it was formerly 

 brought. Although the name has been 

 applied to all the species of Tripoli, yet, 

 strictly, it ought to be confined to those 

 varieties only which are most light and 

 friable, and have a very fine grain. Rot- 

 ten stone occurs near Bakewell, in Der- 

 byshire, resting on compact limestone. 

 It is used in polishing metals, stones, 

 and glass, as well as for many other pur- 

 poses. 



ROTU'ND. (rotundus, Lat. ) Round; circu- 

 lar; spherical. Applied to leaves and shells. 



RU'BELITE. > The Tourmaline rubellite of 



RU'BELLITE. S Brongniart ; Tourmaline 

 apyre of Haiiy. Red tourmaline. This 

 mineral is of a red colour, of various 

 shades ; in the form of its crystals it re- 

 sembles schorl, as well as in its power of 

 acquiring opposite electricities by heat. 

 It is translucent, sometimes transparent. 

 Specific gravity 3-07. Its crystals are 

 cylindrical or acicular, and aggregated in 

 groups. Before the blowpipe this mi- 

 neral becomes white, but does not fuse, 

 a circumstance, considering its composi- 

 tion, not easily explained. Its consti- 

 tuents are silex 42'0, alumine 40'0, soda 

 lO'O, oxides of manganese and iron 7'0. 

 In the British Museum there is a speci- 

 men of Rubellite, from the kingdom of 

 Ava, valued at 1000J. Some specimens 

 of Rubellite afford from five to six per 

 cent, of boracic acid, and from two to 

 three of lithion. 



RU'BBLE STONE. The name given by Kir- 

 wan to Greywacke. 



RU'BY. (from rubeo, Lat. to be red, rubis, 

 Fr. rubino, It. rubin, Germ.) The Spi- 

 nell of Werner ; Spinelle rubis of Brong- 

 niart. A transparent red variety of 

 rhombohedral corundum. The ruby is a 

 variety of the same mineral genus as the 

 sapphire, but differs from it in containing 

 rather more silex, and in being less hard. 

 Rubies are found in alluvial soil in Cey- 

 lon, Pegu, and other countries in the 

 East. The ruby ranks next to the dia- 

 mond in value. When a specimen is 

 fine, and free from flaws, a ruby of large 

 size will sell for from ten to fifteen thou- 

 sand pounds. It is composed principally 

 of alumine, containing not less than ninety 

 per cent. 



RU'GGED. (from ruga, Lat. a wrinkle.) 

 Rough ; uneven. In botany, applied to 

 leaves when the surface rises into little 

 inequalities above the veins. 



