scorpions, dragon-flies, grasshoppers, and cock-
roaclies. Amonf; fislies, the ganoids and selachi-
ans are represented. The ganoids, having tlieir
entire surface covered with scales, were numer-
ous; sonic of them inhabited shallow water near
the shore, and fed on crustaceans and shell-lish,
for crushing whidi they had a formidable appa-
ratus of conical teeth of a very coni|)licatcd
structure. Others were inhabitants of deep
water, and were more powerful and predaceous
and wore lapid in their movements. Their jaws
were produced into a long snout. like the croco-
dile of the Ganges, and armed with a double
series of enormous teeth, which were sometimes
as nuich as 4 inches long by 2 inches broad, as in
Megalichthys (q.v.), dimensions rarely attained
even by the largest known reiJtiles. Associated
with these were a great ninnbcr of sharks belong-
ing to the Cestraciontidif, a family of which we
have only a single living rei)resentative. (See
Cestr.cioxt. ) They had a long, bony spine,
to strengthen the dorsal fin, and this enabled
them to turn speedily in the water, as they re-
quired to do in seizing their prey. These
spines are often found fossil. The only remains
referred to a higher division of the animal king-
dom yet founil l)clong to the saurian Stego-
cephalia (q.v. ). The Carboniferous also con-
tains the first traces of amphibians. Of these,
only footprints were found in the Lower Carbon-
iferous, but in the coal measures the actual bones
were met with. The Permian beds of both Europe
and America have furnished the first reptilian
remains: these belonged to the tribe RhjTicoce-
phalia, which is now nearly extinct.
The alternation of rocks of difTerent character show that oscillations of the land surface must have V)een extensive and long continued, though not violent. Thus the great beds of coal indicate a period of inland shallow water in which swam])y conditions existed. These must have continued for a long period, for the coaMieds are often very thick, and it has been calculated that an eighth of an inch of coal means at least one inch of plant accinuilation. That these swamp areas became at times submerged to some depth, due to the sinking of the land, is indicated by the presstire of limestone-beds over them. The cli- mate that predominated during the Carbonifer- ous was one of warmth and moisture, with the percentage of carbon dioxide in the atmosphere somewhat greater than it is now. but not neces- sarily excessive.
The great importance of the economic min- erals in the Carboniferous has had much to do with our extensive knowledge of it. It is esti- mated that there are 400,000 square miles of the earth's surface imderlain by productive coal- fields. (See Co.L. ) In addition to the coal de- posits, many other useful minerals are found in the Carboniferous of the United States. The elay-beds associated with the coal-seams alTord valuable supplies of fire-clays, pottery-days, and brick-days: iron ores are found in Pennsylvania, Kentucky, and Ohio. Building-stones are quar- ried in the Carboniferous of nuiny States, the sandstones of Berea. Ohio, being specially impor- tant. The Lower Carboniferous strata furnish salt in Ohio. .Michigan, and West Virginia, and zinc ore in Missouri, Kansas, and Arkansas. Consult: Dana, Manual of Genlorjy (New York, 1895) : Geikie, Text-hook of Geology (London, 189.3) ; United States Geological Survey Bulletin No. .80 (Washington, 1891). See Co.L; Geol- ogy; Ci..Y; Iron.
CARBONS, Electric Light. See Electric LiGirn.xo.
CARBORUNDUM. A compound of carbon and silicon with the foriuuhi SiC. the two ele- ments being united atom to atom. It crystallizes in small rhombohedral plates of hexagonal out- line, which may be colored by imi)urities in various shades of blue or green. The substance, possessing a hardness that exceeds that of the ruby, is largely used as a substitute for emery and corundum for abrasive purposes. It is manu- factured in an electric furnace by exposing a mix- ture of carbon and sand to a high and long-ccm- tinued heat. The <rvstals are crushed, and the powder digested with dilute sulphuric acid to re- move impurities: after which it nuiy be made into wheels, polishing cloth, etc. The output in 1900 bv the works ii't Niagara Falls, N. Y.. was 2,401.000 pounds, valued at .$216,000. Carhorun- diun was first obtained by E. S. .Acheson in 1890, during a series of experiments for the production of artificial diamonds.
CARBOY (Pers. tjaruhah, a sort of bottle). A large glass bottle, cased in wicker, or ;)ro- tected by a wooden box. used to contain acids or other corrosive liquids, such as sulphuric acid (oil of vitriol). A carboy of sulpliuric acid con- tains about ItiO pounds of that acid.
CARBUNCLE (OF., from Lat. earhiDieiihis, gem, from earbo. coal). A name applied to the scarlet and crimson varieties of ganiet when cut with a convex face [en eaborhoii) . The ancients applied the name indiscriminately to all red and fiery stones, as spinel and Oriental ruby. Car- buncles Avere highly prized for their supposed mysterious jiower of giving out light in dark- ness. According to the Tahnud. the only light that Noah had in the ark was furnished by car- buncles and other precious stones. The fanxms necklace of Mary (,)ueen of Scots had a lustrous carbuncle as a pendant.
CARBUNCLE (Lat. earbuncuUis. a little coal). An acute inflammation of the cellular or connective tissue beneath the skin, that may occur on any part of the body, but is more frequent on dorsal surfaces, especially on the back of the neck and shoulders. It derives its name from the two most prominent symi)toms — redness and burning pain. It quite closely re- sembles, especially in its early stages, the com- mon furuncle, or hoil, but the s_^^nptoms, both local and general, are nuich more severe. The devcloinnent of the carbuncle is accomiianied by constitutional disturbances, such as chills, fever, aching, and gciu'ral malaise. The severity of the inflammation varies, and is regularly ac- companied by death of a portion of the tissue. The first local manifestation consists in slight swelling and redness. The part feels hard, and this hardness extends deeply into the tissues. As the local lesion advances, the redness as- sumes a dark purple or livid hue. and several small blisters appear on the surface. These open , and discharge a thin, viscid fluid, rarely pus. At the centre of the carbuncle the tissiu- usuall.v dies, and, becoming gangrenous, constitutes the 'core.' This central area is generally quite extensive, and consists of an infiltration of a mass
