TUB 



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TUN 



TUBI'PORA. } Organ-pipe coral, consisting 



TU'BIPORE. $ of tubes of a stony sub- 

 stance, each containing a polype. A 

 genus of corals or zoophytes belonging 

 to the class Polypifera ; subregnum Cyclo- 

 neura, or Radiata. There are several 

 species. In one species, Tubipora mu- 

 sica, the tubes are placed parallel to 

 each other, like the pipes of an organ, 

 with transverse partitions at regular in- 

 tervals : in another species, Sertularia, 

 the tubes are joined together endwise, 

 like the branches of a tree, leaving la- 

 teral apertures for the protrusion of the 

 tentacula of each separate polype. Tu- 

 bipores are found among the earliest 

 traces of organic bodies in the ancient 

 strata. 



TUBI'PORITE. A fossil tubipore. Many 

 marbles and,, pebbles are beautifully 

 marked by the sections of the inclosed 

 tubipores. One very remarkable form 

 is found in the Dudley limestone, the 

 tubes, which are oval, being arranged in 

 undulating lines ; from its reticulated 

 appearance it has obtained the name of 

 chain coral. The pebbles gathered upon 

 the coast of Sussex frequently display 

 beautiful specimens of tubiporse : these 

 are cut, polished, and formed into orna- 

 mental articles. 



TUBTPORI'TIC. Containing tubiporse ; as 

 tubiporitic marble, &c. 



TU'BULAR. In the shape of a hollow tube. 

 In botany, applied to the florets of a 

 compound flower, when they form a 

 cylindrical tube, and are five -cleft. 



TUBULA'RIA. (from tululus, a hollow pipe, 

 Lat.) A genus of corals belonging to 

 the class Polypifera. Simple or branched 

 tubes of a horny substance, each tube 

 containing a polype. Tubularise are both 

 fresh-water and marine. Some species 

 of this genus establish themselves in the 

 fissures of rocks, which serve them in- 

 stead of a shell to protect the mem- 

 branous tubes into which they retract 

 their petaliform tentacles. Of this kind 

 is theTubularia magnifica of Shaw; found 

 in the rocks of the coast of Jamaica. 



TUBULA'RII. (tulularius, Lat.) A family 

 of the order Coralliferi, class Polypi. 

 The tubularii inhabit tubes of which the 

 common gelatinous body traverses the 

 axis, like the medulla of a tree, the tubes 

 being open, either at their sides or sum- 

 mits, to allow the passage of the polypi. 

 Dr. McMurtrie, 



TU'FA. (tuf, Fr. tufo, It.) An earthy 

 precipitate deposited from water. See 

 Calcareous Tufa. 



TUFF. } A name applied to se- 



TTJ'FA,VOLCA'NJC. \ veral different sub- 

 stances the production of volcanic erup- 

 tions. Generally, an aggregate of sand, 



volcanic ashes, and fragments of scoria 

 and lava, united by an argillaceous or 

 muddy cement. Sometimes it is com- 

 posed of volcanic ashes and sand, trans- 

 ported and deposited by rain water. 



Tuff, or volcanic tufa, as distinguished 

 from calcareous tufa, presents various 

 shades of grey, brown, red, yellow, &c. 

 or it is sometimes spotted. Hardness mo- 

 derate ; fracture dull and earthy. 



TUFA'CEOUS. Having the appearance or 

 texture of tufa. 



TU'NGSTEN. (from tung, heavy, and sten, 

 stone, Dan.) 



1. A greyish white metal, brittle, and 

 very hard. Specific gravity 17*4. Fusible 

 in the most intense heat only, its infu- 

 sibility equalling that of platinum. It 

 has been obtained only in the form of 

 grains of extreme hardness. It was dis- 

 covered by Scheele, and by Werner has 

 been named Scheel ; by Haiiy, Scheelin. 



2. A mineral, of a grey or yellowish- 

 grey colour, occurring in Bohemia, 

 Sweden, and Cornwall, massive and dis- 

 seminated. Its external lustre is shining 

 and splendent ; internal lustre shining 

 and resinous. Specific gravity from 5 P 57 

 to 6*06. It can be scratched with a 

 knife, and is easily broken. It is infu- 

 sible, but before the blow-pipe it becomes 

 opaque, and decrepitates. By digestion 

 in nitric acid it is converted into a yellow 

 powder, which is the oxide of tungsten. 

 It consists of oxide of tungsten 77'75, 

 lime 17'60, silex 3'00, according to Klap- 

 roth : Berzelius gives its analysis as con- 

 sisting of oxide of tungsten 80'24, lime 

 19-40. It is the Scheelin calcaire of 

 Haiiy and Brongniart ; the schwerstem 

 of Werner ; the tungsten of Kirwan. 



TU'NICARIES. A class of acephalous mol- 

 luscs in Lamarck's arrangement. The 

 Rev. W. Kirby says, " the characters of 

 the class may be thus stated : animal 

 either gelatinous or leathery, covered by 

 a double tunic, or envelope. The ex- 

 ternal one, analogous to the shell of mol- 

 luscans, distinctly organized, provided 

 with two apertures ; the interior envelope, 

 analogous to their mantle, provided also 

 with two apertures, the one oral, the 

 other anal, adhering to those of the outer 

 one. Body oblong, irregular, divided in- 

 teriorly into many cavities, without a 

 head ; gills occupying, entirely or in 

 part, the surface of a cavity within the 

 mantle ; mouth placed towards the bot- 

 tom of the respiratory cavity between the 

 gills ; alimentary tube, open at both ends ; 

 a ganglion, sending nerves to the mouth 

 and anus. These animals are found both 

 simple and aggregate, fixed or floating." 

 Bridgw. Treat. 



TUNICA'TA. (tunicatus, coated, Lat.) The 



