The term ivory, originally derived from a Greek word signifying heavy, is indiscriminately applied to the following varieties of osseous matter:—­

1. The tusks and teeth of the elephant.—­Naturalists recognise two species of elephants—­the Asiatic (Elephas Indicus) and the African (Elephas Africanus.) The former of these species is indigenous to the whole of Southern India and the Eastern Archipelago; but the largest and most valuable Indian elephant is that of Ceylon.  The second species is found throughout the whole of Africa; and on the banks of the great rivers and lakes of the unexplored regions of the interior, hordes of the finest African elephants are supposed to wander in security.  It was until very recently believed that the Asiatic elephant yielded the largest teeth, and those imported from Pegu, Cochin-China, and Ceylon, sometimes weighed 150 lbs.  Specimens, however, have been obtained from the interior of Africa of much greater weight and dimensions.  Mr Gordon Cumming has in his collection a pair of teeth taken from an old bull elephant in the vicinity of the equator, of which the larger of the two measures 10 feet 9 inches long, and weighs 173 lbs.; and Mr Cawood, who resided thirty years at the Cape, has another pair in his possession measuring 8-1/2 feet each, and weighing together 330 lbs.

Besides these contemporary races of elephants, the market is extensively supplied by the fossil ivory derived from the tusks of the great mammoth or fossil elephant of the geologist.  The remains of this gigantic animal are abundantly distributed over the whole extent of the globe.  They exist in large masses in the northern hemisphere, deeply embedded in the alluvial deposits of the tertiary period.  Humboldt discovered specimens on some of the most elevated ridges of the Andes; and similar remains have been found in Africa.  In the frozen regions of the far North, surrounded by successive layers of everlasting ice, the fossil ivory exists in a state of perfect preservation, and it constitutes indeed an important article of commerce in the north of Europe.

2. The teeth of the hippopotamus, or river-horse.—­These, under the inappropriate term of ‘sea-horse teeth,’ supply the most suitable ivory for the dentist.  In addition to twenty grinders, the animal has twelve front teeth, the outer on each side of the jaw being the largest and most prized.  This ivory is much harder, closer in the grain, and more valuable than that of the elephant.  It is remarkable, moreover, for the extreme hardness of its enamel, which is quite incapable of being cut, and will strike fire with a steel instrument.  The large teeth of the hippopotamus weigh on the average 6 lbs., and the small ones about 1 lb. each.  Their value ranges from 6s. to 40s. per lb.