[Footnote 222: See Mr Home's Observations on the Teeth of Graminivorous Animals, Phil. Trans. 1799. Also, an Essay on the Structure of the Teeth, by Dr Blake.] [Footnote 223: In a paper inserted in the fourth volume of the American Philosophical Transactions, an account is given of two different grinders that are found at the Salt Licks near the Ohio. One of them resembles the grinder of the elephant, and may have belonged to the _Elephas Americanus_ of Cuvier; the other agrees pretty nearly with the grinder of Dr Hunter's _animal incognitum_. The author of the paper thinks that the _animal incognitum_ was not wholly carnivorous, as the incisores, or canine teeth, are never found. At the Great Bone Lick, bones of smaller animals, particularly of the buffalo kind, have been discovered. The saline impregnation of the earth at these Licks must no doubt have contributed to the preservation of the bones. Trans. American Phil. Soc. vol. iv. (1799,) p. 510, &c.] [Footnote 224: Observations on the Grinding Teeth of the wild boar and _animal incognitum_. Phil. Trans. 1801, p. 319.] 412. Another _animal incognitum_ found in South America has been described by Cuvier, and appears to be of a different genus from the _incognitum_ of the North. Thus, if we include the two _incognita_ of America, the _elephas mammonteus_, the unknown buffalo of Pallas, and the great animal of Bayreuth, we have at least five distinct genera, or species of the animal kingdom, which existed on our continents formerly, but do not exist on them now. The number is probably much greater: Pallas mentions fossil horns of a gazelle, of an unknown species; and horns of deer are often found, that cannot be referred to any species now existing. Those extinct races have been remarkable for their size: some of the ancient elephants appear to have been three times as large as any of the present.[225] [Footnote 225: Camper, Nov. Acta Petrop. tom. ii. (1784) p. 257.]