CORRESPONDENCE. 
361 
the Carboniferous beds and the Silurian system.— Oolite , a Limestone group, 
composed of an aggregation of spheroidal grains .—Organic remains, the relies of 
animals and plants.— Orthoceratite , a strait, fossil multilocular shell.— Ossicula ? 
small bones. 
Palceotherium, an extinct quadruped, allied to the Tapir.— Peperino , a volcanic 
aggregate.— Petroleum, mineral oil.— Pisolite, minerals having a structure resem¬ 
bling peas agglutinated together .—Plastic Clap , a Tertiary deposit.— Plesiosaurus , 
an extinct marine animal, allied to the Lizard.— Pliocene, more recent, modern 
Tertiary.— Polyparia , Corals.— Porphyry , a species of ancient lava.— Producta , 
a genus of fossil bivalve marine shells, found in the lower Secondary rocks, and 
allied to Terebratula. — Pterodactyles, a genus of extinct winged reptiles.—- 
Pumice , a light Spongy lava.— Pyrites, Sulphuret of Iron. 
Quartz, a mineral composed of pure Silex. 
Saurian , a division of the Lizard-family.— Scaphite, an extinct genus of 
Cephalopoda , of a boat-like form.-— Scoriae, volcanic cinders.— Sedimentary , 
deposited by water.— Septaria , nodular masses of Clay, having crevices filed 
with Spar.— Shale, Slaty Clay.—SVfer, Flint.— Silica, the base of Flint.—SY&, 
fluviatile deposits of mud, &c.— Spirifera, an extinct genus of bivalve shells.—- 
Stalactite, pendent masses of Carbonate of Lime.— Stalagmite , Calcareous con¬ 
cretions formed on the floors of caverns by the dripping from stlaactites.— Stellular , 
having star-like markings.— Stratum , a layer of any deposit.— Syenite , a species 
of Granite in which Hornblende supplies the place of Mica. 
Tertiary , applied to formations or strata newer than the Chalk.— Trachyte , 
lava composed chiefly of Felspar .—Trap rocks , ancient volcanic rocks, the name 
of which is derived from a Swedish word, Trappa , a stair.— Trilobite , an extinct 
family of Crustacea , the body being divided into three lobes, whence the name. 
-— Tuff, earthy volcanic rock.— Tufa, a Calcareous precipitate from water.—• 
Turrilite, a spiral multilocular shell of the Chalk. 
Unconformable , applied to strata lying in a different plane from those on which 
they rest. 
Veins , fissures in rocks, filled up by mineral substances. 
CORRESPONDENCE. 
Botanical Queries. 
To the Editor of The Naturalist. 
jSiR,— What is the real difference in Botany between abnormal and aberrant , 
with examples 'What are accessory principles , and can tabasheer, raphides, &c., 
