These mongrels form a secondary race, which mix and multiply among themselves, and with the first race; so that in this species, as well as in that of other domestic animals, there are many varieties, the most general of which are relative to the difference of climate. Aristotle has judiciously marked the two principal races; the first, which has two hunches, under the name of the _Bactrian Camel_; and the second under that of the _Arabian Camel_: the first are called _Turkish_ and the others _Arabian Camels_. This distinction still subsists, but it appears, since the discovery of those parts of Africa and Asia which were unknown to the ancients, that the dromedary is, without comparison, more numerous and more universal than the camel: the last being seldom found in any other place than Turkestan, and some other parts of the Levant; while the dromedary, more common than any other beast of burthen in Arabia, is found in all the northern parts of Africa, from the Mediterranean to the river Niger, and is also met with in Egypt, in Persia, in Southern Tartary, and in all the northern parts of India. The dromedary, therefore, occupies an immense tract of land, while the camel is confined to narrow limits. The first inhabits hot and parched regions; the second, a more moist soil and temperate climate; and the whole species, as well the one as the other, appears to be confined to a zone of three or four hundred leagues in breadth, which spreads from Mauritania to China, for they subsist neither above nor below this zone, and although a native of warm climates, this animal is averse to those where the heat is excessive; his species ends where that of the elephant begins, and it cannot exist either under the burning heat of the torrid zone, or in the milder climates of the temperate. It appears to be originally a native of Arabia, for that is not only the country where they are the greatest in number, but where they seem to be in the best condition. Arabia is the most dry country in the world, and one in which water is the most scarce. The camel is the least thirsty of all animals, and can pass several days without any drink. The land is almost in every part dry and sandy. The feet of the camel are formed to travel in sand; and he cannot support himself on moist and slippery ground. Herbage and pasture are wanting in this country, as is also the ox, whose place is supplied by the camel.