F A TJ 



J 



F E L 



coal-fields, these faults operate as 

 coffer-dams, and are of the greatest 

 possible advantage. Faults are of 

 two kinds, true faults, and Symon 

 faults. When a stratum of coal 

 tapers away and disappears amid 

 the shales and sandstones, it is 

 locally termed a "Symon" fault. 

 See Symon Fault. 



FA'UNA. (fount, Lat.) As the 

 plants peculiar to a country con- 

 stitute its flora, so do the animals 

 constitute its fauna ; the zoology 

 of a country. 



FATTX. (Fr.) That portion of the 

 cavity of the first chamber of a 

 shell which may be seen by looking 

 in at the aperture. 



FAVOSITES. A genus of foraminated 

 polypifers, resembling the honey- 

 comb in appearance, from which 

 circumstances the name has been 

 applied. 



FAVTTLA'RIA. A genus of fossil plants. 

 Stem-furrowed ; scars of leaves 

 small, square, and of a breadth 

 with the ridges of the stem. In 

 the favularia, the trunk was 

 entirely covered with a mass of 

 densely imbricated foliage, the 

 bases of the leaves are nearly 

 square, and the rows of leaves 

 separated by intermediate grooves. 

 The genus is believed to be extinct, 

 but is found fossil in the coal 

 formation. 



FEA'THERY. Plumose; applied to 



plants furnished with lateral hairs. 



FECU'LA. (from fax Lat. fecule, Fr.) 



1. The sediment or grounds of any 

 liquid. The word fecula, says 

 JDr. Paris, originally meant to 

 imply any substance which was 

 derived by spontaneous subsidence 

 from a liquid. 



2. The green matter of plants. 

 FEE'LEES. In conchology, those 



crenated arms, evolved from the 

 side of the Lepas anatifera, and 

 other shells of the second division 

 of Lepas. While the animal is in 

 the water it continually moves its 



feelers, evidently for the purpose 

 of entangling minute marine insects 

 as food. Brown. 



FE'LDSPAB. } A mineral which enters 

 FE'LSPAE. ) into the composition 

 and, next to quartz, constitutes 

 the chief material of many rocks. 

 There are many species and sub- 

 species, or varieties of this mineral, 

 though all agree nearly in their 

 chemical composition, and all are 

 found both crystallised and massive. 

 Feldspar is lamellar in its structure, 

 but not in so great a degree as 

 mica; it scratches glass, and is 

 nearly opaque. It is composed of 

 silex 64, alumina 18, potash. 13, 

 lime 3, and some oxide of iron. 

 Common feldspar is perhaps the 

 most generally diffused mineral, 

 next to quartz and iron. It is one 

 of the components of granite, 

 gneiss, and some other primary 

 rocks ; and granite owes its variety 

 of appearance and colour principally 

 to the abundance, or otherwise, of 

 the feldspar it contains. In some 

 kinds of granite the feldspar is in 

 large whitish crystals of irregular 

 forms, occasionally of one or two 

 inches in length. From the lia- 

 bility of feldspar to be decomposed 

 by atmospheric action, granite 

 containing large crystals of it is 

 less durable than that which is 

 finer grained, and it is said that 

 Waterloo-bridge, being unfortu- 

 nately built of granite containing 

 large crystals of feldspar, will be 

 less durable than could be wished 

 for. Felspar forms, in general, 

 more than half of the mass of 

 modern lavas. When it is in 

 great excess, lavas are called 

 trachytic; when augite (or py- 

 roxene) predominates, they are 

 termed basaltic. 



Felspar assumes a considerable 

 variety of forms, which differ so 

 greatly from each other, that a 

 novice finds it difficult to recognise 

 in them the same substance. In 



