X I P 



[465 ] 



Y T T 



a<$o<?, form.) Resembling a sword : 

 a term applied to the cartilage 

 placed at the lower extremity of 

 the sternum or breast-bone. 



XIPHOS'URA. The seventh order of 

 the class Crustacea, comprising the 

 king-crab, or limulus, and the 

 extinct genera Halycina and Belli- 

 nurus. 



XULINOSPBIONI'TES. The name given 

 to a genus of fossil fruits found in 



the London clay. Mr. Bowerbank 

 describe them thus : " legumes 

 valveless, woody, two-seeded," and 

 observes " the pericarp of the fruits 

 of this genus unites, in a singular 

 manner, the characters of the 

 legume and the drupe." 

 XYLO'PHAGI. (from gv\ov, wood, 

 and 0a7etV, to eat, Gr.) A family of. 

 coleopterous insects, comprising 

 several genera. 



YA'NOLITE. The name given by 

 Lametherie to the Axinite of Haiiy 

 and the Thummerstone of Kirwan. 



YE'LLOW-QUARTZ. (The Quartz hyalin 

 Jaune of Haiiy.) A variety or 

 sub-species of quartz, of various 

 shades of yellow, and nearly trans- 

 parent. It has been also called 

 citrine and false or Bohemian topaz. 

 In Scotland it has obtained the 

 name of Cairn-gorm. 



YE'NITE. So named from Jena. 

 Called also Lievrite. It is found 

 in the Isle of Elba and in Norway. 

 A mineral of a black or blackish- 

 green colour, occurring crystallized 

 and massive. It is opaque; scratches 

 glass; gives sparks with steel. 

 Specific gravity from 3 8 to 4, 

 Longitudinal fracture foliated ; 

 cross fracture conchoidal or uneven : 

 lustre resinous. Before the blow- 

 pipe it fuses into a dull, opaque, 

 black globule, strongly attracted 

 by the magnet. It consists of silex 

 30-0, lime 12-5, oxide of iron 57'5. 



YU'CCITES. A genus of plants, thus 

 designated by Dr. Martins, and 

 which, he says, constitutes a series 

 allied to the palms, differing in 



structure from most of the monoco- 

 tyledons, in having the stem 

 broadly expanded above by a more 

 or less perfect dichotomy. 



Y'TTRIA. A name given by Ekeberg 

 to a new earth discovered by Gad- 

 olin, in 1797, in the quarry of 

 Yetterby, in Sweden. It has also 

 been named Gadolinite, after 

 Gadolin. The equivalent of Yttria, 

 according to Berzelius, is 40*2. 



Y'TTRITJM. The name given by Eke- 

 berg to a metal forming the basis 

 of Yttria. In that mineral it is 

 combined with the oxides of iron 

 and manganese, and a small portion 

 of lime, and silica. "When separ- 

 ated from these substances, it has 

 the appearance of a fine white 

 powder, without either taste or 

 smell. It is infusible, and is inso- 

 luble in water. Its equivalent, 

 according to Berzelius, is 32-2. 



YTTROTA'NTALITE. The name given 

 by Brochant to Ittrious oxide of 

 Columbium. Yttrotantalite, like 

 like Yttria, is found in the quarry 

 of Ytterby, in Sweden. It is of a 

 dark grey colour ; shining, metallic 

 lustre ; found in reniform masses. 



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