T A L 



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TEL 



TA'LUS. (talus, Lat. talus, Fr. inclinaison 

 que Von donne a la surface laterals et 

 exterieure d*un mur, de telle sorte que de 

 haut en has il aille toujours en *' fyaissis- 

 sent. Jl se dit aussi d'une terrasse san# 

 murs, lorsque ses faces lattrales s'elargis- 

 sent de haut en bos.) 



1. A sloping heap. When, from disinte- 

 gration, the fragments of a face of rock 

 accumulate at its base and form a sloping 

 heap, the heap is called a talus. 



2. In anatomy, a name sometimes given to 

 one of the bones of the tarsus, the astra- 

 galus. 



TA'NGENT. (from tango, to touch, Lat. 

 tang eiite, Fr. tangente, It.) A straight 

 line which touches a curved line in one 

 point without cutting it. 



TA'NTAHTE. The name given by some 

 mineralogists, and in the first instance by 

 Ekeberg, to the ferruginous oxide of co- 

 lumbium. The tantale oxide ferro- 

 manganesifere of Haiiy ; the tantale tan- 

 talite of Brongniart. Called also colum- 

 bite. The ore of tantalum or columbium. 

 When recently broken, tantalite is of a 

 dark bluish-gray or nearly iron-black 

 colour. It occurs in octohedral crystals, 

 and in small masses. Its specific gravity 

 is from 5 '9 to 7' 9. It consists of oxide 

 of columbium 80'0, oxide of iron 12*0, 

 oxide of manganese 8'0. It has been 

 found in Finland, and in the United 

 States of America. 



TA'NTALUM. A metal extracted from tan- 

 talite ; it appears to be the same sub- 

 stance as columbium, and identical with 

 it. 



TA'PIR. A genus of mammalia, belonging 

 to the family Pachydermata Ordinaria. 

 The nose of the tapir may be compared 

 to a small fleshy proboscis, the snout 

 being lengthened and moveable. There 

 are several species of this genus still sur- 

 viving, but they are all natives of tropical 

 climates. The general appearance of the 

 tapir is that of a pig, but some of the 

 species are as large as the ass. The fore 

 feet have four toes each, all of equal size ; 

 the hind feet have only three each. The 

 skin is of a dark colour, nearly black, 

 with but few hairs. 



Fossil tapirs are found in different parts 

 of Europe. 



TAP-ROOT. In botany, the main root of a 

 plant, which passes directly downwards. 



TARDIGRA'DA. ) (from tardigradus, slow- 



TA'RDIGRADE. $ paced, Lat.) A family 

 of quadrupeds of the order Edentata. 

 These animals have obtained their name 

 from the extreme slowness of their mo- 

 tions. The only existing genus is the 

 Bradypus or sloth. Their nails are enor- 

 mously long, compressed, and crooked. 

 The molars are cylindrical ; the canini 



sharp, and longer than the molars. They 

 live in trees, and so great is their indis- 

 position to locomotion, that they continue 

 on the same tree till they have devoured 

 every leaf to be found thereon. Some 

 authors state that, to avoid the trouble of 

 a regular descent, they tumble themselves 

 down from the branch they happen to be 

 on. When they have eaten their full, 

 they can roll themselves into a ball, and 

 take a long and reckless sleep. 



TAR MI'NERAL. A variety of bitumen, 

 bearing a great resemblance to petroleum, 

 but more viscid, and of a darker colour. 



TARN. A bog ; a fen ; a marsh ; a pool. 

 This word appears to be of Icelandic 

 origin. 



TA'RSAL. Pertaining to the tarsus or in- 

 step, as the tarsal bones, &c. 



TA'RSUS. (rapaoQ, Gr. tarse, Fr.) 



1. The instep, or that part of the foot 

 situated between the bones of the leg and 

 the metatarsus. 



2. In entomology, the tarsus, or foot, of 

 insects is the last division of the limb : it 

 is divided into several joints, which have 

 been supposed to represent the toes of 

 quadrupeds. The last joint of the tarsus 

 is generally terminated by a claw, which 

 is sometimes single and sometimes double, 

 and which contributes to fasten the foot, 

 under a variety of circumstances both of 

 action and repose. The hooks of the 

 anterior tarsi are directed backwards, 

 those of the middle pair inwards, of the 

 hindermost pair forwards. Many insects 

 are provided with cushions at the ex- 

 tremity of the feet, which break the force 

 of falls, and prevent the jar which the 

 frame would otherwise have to sustain. 

 These cushions are formed of dense vel- 

 vety tufts of hair, lining the underside of 

 the tarsi, but leaving the claw uncovered. 

 Rev. W. Kirby. 



TA'RTARIN. ) Vegetable alkali, or potash : 



TA'RTARINE. 5 a name assigned to it by 

 Kirwan. 



TAXO'NOMY. (from ratc., order, and 

 VO^OQ, law, Gr.) The classification or 

 arrangement of animals or plants, accord- 

 ing to certain principles, in divisions and 

 groups. 



TE'GMEN. (tegmen, any sort of covering, 

 Lat.) A covering of the body, as the 

 cuticle, &c. ; used in botany to denote one 

 of the coats of the seed ; in entomology, 

 applied to the coverings of the wings of 

 the order Orthoptera, or straight-winged 

 insects. 



TE'GUMENT. The same as teamen. 



TELEOSA'URUS. A new genus of fossil 

 saurians, thus named and arranged by M. 

 Geoffroy St. Hilaire. The teleosauri have 

 long and narrow beaks, the nostrils form- 

 ing almost a vertical section of the an- 



