S C A 



[ 229 J 



S C H 



southern flanks of the Tyrolese Alps, the 

 tertiary strata are described as forming a 

 vast series of beds resting on scaglia or 

 chalk. The scaglia occurs in beds nearly 

 vertical ; the upper ones contain nodules 

 and layers of flints ; their colour is red, 

 and their structure fissile. The scaglia 

 contains in some parts ammonites and 

 belemnites. Mr. Bakewell, Introd. to 

 Geology. 



SCALA'RIA. A genus of marine turreted 

 univalves, with acute longitudinal raised 

 ribs. The aperture nearly circular ; the 

 margins uninterrupted, bordered, and re- 

 flected. Scalarise are found in sandy 

 mud at depths varying from seven to 

 thirteen fathoms. Lamarck has described 

 five species of this genus as found among 

 the fossils of Grignon and Femes. 



SCALA'RIFORM. (from scalaris, a ladder, 

 and forma, form, Lat.) Mr. Robert 

 Brown has ascertained by examination of 

 a trunk of Cycadites mycrophyllus, from 

 Portland, the existence of scalariform 

 vessels without discs, in the mature 

 trunk. 



SCA'LLOPED. Indented at the edges. 



SCA'NDENT. (from scandens, climbing, 

 Lat.) A term applied to plants which 

 climb upon some support, attaching them- 

 selves by fibres or tendrils. 



SCAPE, (from scapus, Lat.) In botany, 

 an herbaceous stalk springing from the 

 root, and bearing the flower and fruit, 

 but not the leaves. The hyacinth, cow- 

 slip, and dandelion, are examples. 



SCA'PHITE. (from scapha, a boat.) So 

 named from its supposed resemblance to 

 a boat. The scaphite resembles an am- 

 monite partly unrolled. Scaphites are 

 found in the chalk and in the greensand. 

 They are believed to be altogether ex- 

 tinct ; but the Rev. W. Kirby most justly 

 remarks, " who shall say what species 

 lurk in those unapproachable recesses 

 never to be revealed to human eye, but 

 in a fossil state. The baculites, hamites, 

 scaphites, and numerous others, there 

 have space sufficient to live unknown to 

 fame, while they are reckoned by the 

 geologist as expunged from the list of 

 living animals." 



SCA'POLITE. Pyramidal felspar. The sca- 

 polith of Werner ; scapolithe of Bro- 

 chant ; paranthine of Haiiy. A rare mi- 

 neral, occurring massive and in long 

 prismatic crystals. It consists of silica 

 43-83, alumina 35-43, lime 18-96. It is 

 of a grey, yellowish, greenish-white, or 

 silver-white colour. Specific gravity from 

 3'68 to 3-71. Before the blow-pipe it 

 intumesces, and fuses into a shining, 

 white enamel. It is found in beds of 

 magnetic ironstone and iron pyrites, at 

 Arendal, in Norway. 



SCA'PULA. The shoulder-blade. 



SCA'PULAR. Pertaining Jto the shoulder- 

 blade or scapula. 



SCARF-SKIN. The cuticle or external co- 

 vering of the body ; called also the epider- 

 mis. 



SCHAA'LSTEIN. Shell-stone. The schaal- 

 stone of Jameson ; pierre calcaire tes- 

 tacee of Brochant ; spath en table of 

 Haiiy. Called also tabular spar or table 

 spar. A substance of a grey or pearly- 

 white colour, usually occurring in masses, 

 composed of thin laminae, collected into 

 large prismatic concretions. It is very 

 rare, and has been found chiefly at Dog- 

 natska, in the Bannat. 



SCHEE'LIUM. Another name for Tung- 

 sten. 



SCHI'LLER SPAR, (from schillerm, Germ. 

 to vary colours, to play from one colour 

 to another.) The schiller spath of Mohs. 

 A genus of spars comprising four varie- 

 ties, namely, common schiller spar ; 

 bronzite, or hemiprismatic schiller spar ; 

 hypersthene, or prismatoidal schiller 

 spar ; and anthophyllite, or prismatic 

 schiller spar. The characters of the 

 genus are, the cleavage monotomous, per- 

 fect. Metallic pearly lustre. Hardness 

 =3-5 to 6-0. Specific gravity = 2-6 to 

 3.4. 



SCHIST. (rrxiffroQ, Gr. schistus, "Lat.schiste, 

 Fr.) A term synonymous with slate. A 

 rock, of a fissile character, which may 

 easily be split. 



. 



SCHISTO'SE MI'CA. The name given by 

 Kirwan to mica slate. 



SCHNEIDE'RIAN MEMBRANE. Thus named 

 from Schneider, who first described it. 

 The lining membrance of the nostrils. 



SCHORL. A dark-coloured, opaque, variety 

 of tourmaline. It occurs crystallized ; 

 in prismatic and granular concretions, 

 massive and disseminated. The electric 

 powers of schorl constitute one of its 

 most striking characters. By friction it 

 becomes positively electric ; but by ex- 

 posure to heat, it acquires positive elec- 

 tricity at one end, and negative at the 

 other. Schorl is brittle ; it scratches 

 glass ; is harder than hornblende, but 

 less hard than quartz. Fracture vitreous 

 and conchoidal. Specific gravity from 

 3-05 to 3-36. It fuses easily before the- 

 blow-pipe, and is converted into a grey- 

 ish-white or brownish enamel, sometimes 

 nearly compact at others vesicular. Its 

 constituents are, silex 36-75, alumina 

 34-50, potash 6-0, magnesia 0'25, oxide 

 of iron 21'0. It occurs imbedded in 

 granite, gneiss, &c. in Scotland and in 

 Cornwall. 



SCHO'RLITE, The Pycnite of Haiiy and 



