We see, then, that the marsupials in a world of their own, cut off by the sea from the struggling world beyond, play all parts in life; and squirrels, monkeys, insect-eaters, gnawing animals, hoofed animals, and beasts of prey, all have their parallel among the pouch-bearers. But just because they are so isolated it becomes a curious question why, when we travel right across the wide Atlantic or Pacific to America, we find another set of pouched animals slightly different but belonging to the same group. How comes it that the clever little opossums of Guiana, Brazil, and Virginia (see Fig. 53, p. 200), which grasp the trees with the free nailless great toe of their hind feet and hang by their long tails, should be marsupials, carrying their little ones in pouches, when all their relations are thousands of miles away over the sea? [Illustration: Fig. 52. Tasmanian Marsupials. The two to the left of the picture are Wombats;[118] the front right hand figure the Tasmanian Devil;[119] and the background figure the Tasmanian Wolf.[120] ] Stop a moment, and let us go back to those times when the marsupials were living with the great flying reptiles in Europe and North America. These forms (see p. 183) were like the little myrmecobius now living in Australia, and at some period, we do not know exactly when, their descendants must have found their way to that part of the world, where they have since branched out into so many curious forms, gnawing, leaping, running, and flying, and filling the place of ordinary quadrupeds. But they must also have lived on in the Northern Hemisphere and branched out into other forms; for much later, when tigers and other ferocious beasts had begun to prowl about in the forests of Europe and America, opossums were leaping in the trees, as we know by finding their bones in Suffolk, under Paris, and in North America. And so we see that when these opossums found their way down south to Brazil and Guiana, the simile that we used a little while ago (p. 131) probably became literally true, and the Australian and South American pouched animals are related to each other, not because they come one from the other, but because they both come from the same very ancient stock which once lived in Europe.