F E It 



[172] 



FIB 



confined almost exclusively to the 

 tropics; an elevated and uniform 

 temperature and great humidity 

 being the conditions most favour- 

 able to their development. The 

 existence of immense fossil arbo- 

 rescent ferns, from thirty to forty 

 feet in height, in the coal formation, 

 is one of the strongest possible evi- 

 dences of the great diminution of 

 temperature and change of climate 

 which the earth has undergone. In 

 the coal formation there are not 

 fewer than 130 known species of 

 ferns, nearly all of which belong to 

 the tribe of Polypodiaceae. An 

 arborescent fern, forty - five feet 

 high, from Silhet in Bengal, may 

 be seen in the stair-case of the Bri- 

 tish Museum. In the strata of the 

 secondary series there is a consider- 

 able diminution in the absolute 

 and relative number of ferns ; and 

 in the strata of the tertiary series 

 the ferns seem to bear nearly the 

 same proportion to other vegetables 

 as in the temperate regions of the 

 earth at the present day. Auck- 

 land. I/yell. Mantell. 



FER'RUGINOUS QUARTZ. (Called also 

 Iron-flint.) The Eisenkeisel of 

 Werner; Quartz Bubigineux of 

 Haiiy. A subspecies of quartz, 

 opaque, or translucent at the edges 

 only. Fracture uneven, more or 

 less conchoidal, but imperfect, shi- 

 ning, and nearly vitreous. It 

 occurs massive and crystallized. 

 Some authors divide ferruginous 

 quartz into yellow and green 

 varieties. Cleaveland mentions 

 two varieties, yellow and red. 

 Ferruginous quartz consists of sil- 

 ica 93, oxide of iron 5, oxide of 

 manganese 1. 



FE'TID LIMESTONE. The Stinkstein of 

 the Germans. A limestone which, 

 when struck with the hammer, 

 gives off a fetid smell, like that of 

 sulphuretted hydrogen gas. 



FETUS. (fatus, Lat.) Commonly 

 written fatus. Of viviparous ani- 

 mals, the young in utero ; of ovi- 



parous, the young in the shell : in 

 the earliest stages of utero-gestation, 

 the young is usually called the 

 embryo, and when fully formed, or 

 after a certain period, the fetus. 



FI'BER. ] (fibra, Lat. fibre, Fr. fibra, 



FI'BRE. ) It.) A filament or thread, 

 whether of animal, vegetable, or 

 mineral structure. 



FI'BRIL. (fibrille, Fr. petite fibre, 

 fibritta, It.) A small fibre; the 

 diminutive of fibre. 



FI'BROUS. ffibreaux, Fr. fibroso, It.) 

 Composed of fibres ; containing 

 fibres. 



In botany, a fibrous root consists 

 of numerous fibres, either simple 

 or branched; these are the most 

 simple of all roots, conveying nou- 

 rishment directly to the stem, or 

 leaves. 



FIBROUS QUARTZ. See Cat's Eye. 



FI'BROLITE. (from fibra, Lat. and 

 \lOo<s, Gr.) A mineral of a white 

 or grey colour, occurring with 

 corundum. Cleavage imperfect. 

 Hardness more considerable than 

 that of quartz. Consists of alumina 

 46, silica 33, oxide of iron 13. It 

 is composed of minute fibres, from 

 which circumstance it obtains its 

 name, some of which appear to be 

 rhomboidal prisms. It is found in 

 China and in the Carnatic. 



FI'BULA. (Lat.) 



1. The small bone of the leg, thus 

 named, according to some authors, 

 from being placed opposite to the 

 part where the knee-buckle, or 

 clasp, was formerly used. 



2. A fossil echinite, resembling, 

 not a buckle, but a button. By 

 some oryctologists these have been 

 termed Bufonitse and Scolopendritae, 

 and by others Pilei; and, by the 

 English, Capstones. Parkinson. 



FIBULA'RIA. A genus of echinites, 

 subglobular, ovoid and nearly round, 

 with no determinate margin; the 

 ambulacra forming petaloidal, short, 

 narrow, and circumscribed figures, 

 the mouth beneath, central; the 



