Although, as before noted, the camel has a certain value for other purposes than conveying burdens, these subsidiary uses are so far limited that the creature is not likely to retain a place in the world after his service in caravans is no longer called for. The rapid recivilization of northern Africa, leading as it does to the development of a railway system in that region, promises to displace this creature from his most trodden ways. It seems likely that the other portions of the desert lands in the old world will soon be brought under the same civilizing influences, the nomadic tribes reduced to a stationary habit of life, and the commerce effected in the modern manner. When this change is brought about, this old-time animal, which but for the care of man would have probably long since passed away, will be likely, save so far as it may be preserved through motives of scientific interest, to join the great array of vanished species. [Illustration: Camels along the Sea at Twilight] It affords a pleasant contrast to turn from the consideration of the camels to a study of the elephants. The difference in the measure of attractiveness of the two forms is very great, and depends upon facts of remarkable interest. Unlike the camel--which, as we have seen, is the last survivor of an ancient lineage, represented by but two species, and these limited to a small part of the world--the elephant, at the time when man appears to have taken shape, seems to have existed on all the continental lands except Australia, and to have been in a state of singular prosperity. As is often the case with other vigorous genera of mammals, the species were adapted to a very great variety of climates, and were fitted to endure tropic heat as well as arctic cold. The group of elephants is first known to us in the early part of Tertiary time. From its first appearance on our stage it seems to have been successful in a high measure, and this probably by reason of its possession of the remarkable invention of the trunk--a prolonged and marvellously flexible nose which serves in the manner of an arm and hand for gathering food.