Exogenous. Plants which increase their wood by external additions or rings of growth.
Exuviæ. A name sometimes given to all fossil remains found in the earth’s crust.
Fauna. The whole group of animals peculiar to a country or natural region at some one period.
Feldspar. A hard silicious rock.
Ferruginous. Irony, or containing iron.
Fern. (Lat., Felices), a class of cryptogamous plants.
Fissile. Capable of being split asunder.
Flustra. A parasitic zoophyte or polyparia, which covers sea-weeds and shells.
Fæcal sediment. Dregs, excrement.