S P I 



[ 242 ] 



S P O 



enamel. It consists, according to the 

 analysis of Klaproth, of silica 43*0, alu- 

 mina 29-5, soda 19'0, lime 1'4, oxide of 

 iron 2'0, sulphuric acid I'O, water 2'6. 



SPI'NTHERE. The name given by Haiiy to 

 a mineral of a greenish-grey colour found 

 in the department of the Isere, in France. 



SPI'NY. ^ Having spines, thorns, or 



SPI'NOUS. $ points. 



1. In botany, applied to plants possessing 

 thorns or spines ; also to leaves, the 

 margins of which are beset with thorns. 



2. In anatomy, applied to certain pro- 

 cesses of bones. 



SPI'RACLE. (spiraculum, a breathing-hole, 

 Lat. spiraglio, It.) The spiracles are 

 the external orifices from which the air 

 tubes of insects commence : they are also 

 called stigmata. 



SPI'RAL. (from spira, a spire, Lat. spiral, 

 Fr. spirale, It.) Winding in a cir- 

 cular form, and, at the same time, rising : 

 a corkscrew is an example of spiral form. 



SPIRE. (from <T7mpa, Gr, spira, Lat. 

 spire, Fr. spiro, It.) That part of a 

 body which shoots up to a point. 



In conchology, the spire of univalve shells 

 consists of all the whorls except the lower 

 one, which is termed the body. The spire 

 is a prominent feature in univalve shells, 

 and upon its being elevated, depressed, 

 &c., depends much of the generic and spe- 

 cific definition. There are several kinds 

 of spire ; the depressed spire, when the 

 spire is very flat ; the involuted spire, 

 when the whorls are concealed in the in- 

 side of the first whorl, as in the nautilus ; 

 the reversed spire, when the whorls turn 

 in the contrary direction to a right-hand- 

 ed screw, &c. 



SPI'RIFER. (from spira, a spire, and/ero, 

 to bear, Lat.) A genus of bivalve shells, 

 distinguished from terebratula by its very 

 extraordinary internal spiral processes or 

 cones, from which it obtains its name. 



SPIROLI'NA. A genus of microscopic forami- 

 niferous multilocular univalves, described 

 by Lamarck, who discovered several spe- 

 cies of them in the fossils of Grignon. 



SPIRO'RBIS. A genus of shells belonging 

 to the family of the Serpulacea. A fa- 

 miliar example of spirorbis is afforded in 

 the common, small, white, coiled shell so 

 frequently seen upon the shell of the lob- 

 ster. The spirorbis is found on sea-weed, 

 shells, &c. 



SPI'RULA. (from spira, Lat.) Both a 

 recent and a fossil shell. A genus of 

 multilocular shells, partly spiral and partly 

 straight, the whorls being arranged in a 

 discoidal form, and separate from each 

 other ; the last turn being elongated, and 

 continued in a straight line. The siphun- 

 culus, instead of being membranous, is 

 formed by one continuous shelly tube. 



It appears that the spirula, notwithstand- 

 ing it possessed a siphuncle, was, alto- 

 gether or in part, an internal shell. The 

 living spirula is an inhabitant of tropical 

 seas ; it floats on the surface of the ocean. 



SPI'RULITE. A fossil spirula. Spirulites 

 are sometimes termed litnites, from their 

 supposed resemblance to a bishop's pas- 

 toral staff. They are found principally in 

 Normandy, Mecklenberg, and, as is 

 stated, in Switzerland. 



SPLE'NDENT. (splendens, shining, Lat. 

 splendente, It.) In mineralogy, a term 

 applied to metals as regards their degree 

 of lustre. A mineral is splendent when 

 perceptible in full day-light at a great 

 distance, as in highly polished metals. 



SPLENT COAL. An impure variety of can- 

 nel coal, occurring in Scotland. 



SPLI'NTERY. In mineralogy, a term applied 

 to a particular fracture of minerals. The 

 fracture is called splintery, when the sur- 

 face, produced by breaking a mineral, is 

 nearly even, but exhibits little splinters 

 or scales, somewhat thicker at one extre- 

 mity than the other, and still adhering to 

 the surface by their thicker extremities. 

 Cleaveland. 



SPO'DUMENE. (from O-TTO^OW, Gr. in cine- 

 rem redigo.} The Triphane of Haiiy ; 

 Spodumene of Jameson. A rare mineral 

 of a greenish white or gray colour ; oc- 

 curring massive, and in large granular 

 concretions. Spodumene has been found 

 in the iron-mine of Uton, in Sweden, and 

 in primary rocks in Ireland. According 

 to the analysis of Vauquelin, it consists of 

 silica 64*4, alumina 24*4, potash 5'0, lime 

 3'0, oxide of iron 2-2. Arfwedson dis- 

 covered in a specimen of spodumene 

 nearly toine per cent, of lithion. 



SPO'NDYLUS. A genus of rough, slightly- 

 eared, inequivalved, marine, bivalves, with 

 unequal beaks ; hinge with two recurved 

 teeth, separated by a small hollow. Spon- 

 dyli are found only in the ocean, attached 

 to rocks, corals, &c. : they are remarkable 

 for their spines, and the richness of colour- 

 ing of the shells. No species have been 

 found in the seas of our coasts. They 

 are eaten like oysters. 



Lamarck has described one species as 

 occurring fossil in the neighbourhood of 

 Paris, and very fine fossils are found in 

 Tuscany. 



SPONGE. (o-Troyyia, Gr. spongia, Lat. 

 eponge, Fr. spugna, It.) This word is 

 pronounced, and frequently written, 

 spunge. A porous marine substance 

 found adhering to rocks, formerly sup- 

 posed to be a vegetable production, but 

 now classed among the zoophytes : it is 

 soft, light, porous, and easily compressi- 

 ble, readily imbibing fluids, and thereby 

 distending. 



