The mammals, because they are, in qualities of body and mind, nearer to us than the members of any other class of animals, afford the most promising field from which to make selections for future domestication. In an economic sense it seems unlikely that any very great profit can be attained by the subjugation of any of the mammalian species which are still wild. Civilized people have been so long in contact with the life of all the continents, and have ever been so hungry for gain, that they have already essayed about every experiment in subjugating the larger wild beasts which appears to be very promising. Still there are certain cases where there have been no trials and others where the failure to tame particular species has been due to hindrances which systematic labor may possibly overcome. It will therefore be well to glance at the array of the wild forms which afford some prospect of success in the hereafter, including under the title of successes those kinds which may contribute not only to immediately measurable wealth, but the aesthetic satisfactions as well. Beginning with the lowlier group of mammals we find in the base of the series the ornithorhynchus and its allies, creatures which have nothing to recommend them but their exceeding organic peculiarities that render them attractive to the naturalist, but which are not likely to win them a place in the affections of men in general. As these species are most inoffensive as well as interesting, and as they are now confined to a portion of Australia, they might well be made the subject of some human care which would stop short of domestication. They might be transplanted to other continents and thereby given a larger field for variation as well as a chance to exhibit their features in a wider field. Among the pouched mammals, especially in the species of kangaroo, there are forms which commend themselves as very fair subjects for taming. They are of considerable size, their flesh is palatable, and their hides useful for leather; they breed rapidly, live on a poor herbage, and are, for wild animals of like strength, very inoffensive. Moreover, though relatively invariable both in mind and body, they exhibit sufficient individual peculiarities to indicate that the breeder's art could, in a short time, bring about considerable changes such as have been effected in other species, changes that would increase the value of these animals. As far as aesthetic or sympathetic relations are concerned, the pouched mammals have nothing to give us; they are, as befits their lowly estate, among the least graceful of their class; they are also little interesting in their mental qualities, being about the stupidest of our kindred.