For ages Asia appears to have served as a vast and fecund nursery for new mammals from which North Temperate and Arctic America have been supplied. The last and comparatively recent land bridge, across which came the ancestors of our moose, elk, caribou, prong-horned antelope, mountain goats, mountain sheep, musk-oxen, bears, and many other mammals, was in the far Northwest, where Bering Straits now form a shallow channel only 28 miles wide separating Siberia from Alaska. [Illustration: Photograph by L. Peterson INTRODUCING A LITTLE BLACK BEAR TO A LITTLE BROWN BEAR AT SEWARD, ALASKA “Howdy-do! I ain’t got a bit of use for you!” “What do I care! You’d better back away, black bear!”] The fossil beds of the Great Plains and other parts of the West contain eloquent proofs of the richness and variety of mammal life on this continent at different periods in the past. Perhaps the most wonderful of all these ancient faunas was that revealed by the bones of birds and mammals which had been trapped in the asphalt pits recently discovered in the outskirts of Los Angeles, California. These bones show that prior to the arrival of the present fauna the plains of southern California swarmed with an astonishing wealth of strange birds and beasts (see page 401). The most notable of these are saber-toothed tigers, lions much larger than those of Africa; giant wolves; several kinds of bears, including the huge cave bears, even larger than the gigantic brown bears of Alaska; large wild horses; camels; bison (unlike our buffalo); tiny antelope, the size of a fox; mastodons, mammoths with tusks 15 feet long; and giant ground sloths; in addition to many other species, large and small. With these amazing mammals were equally strange birds, including, among numerous birds of prey, a giant vulturelike species (far larger than any condor), peacocks, and many others. DID MAN LIVE THEN? The geologically recent existence of this now vanished fauna is evidenced by the presence in the asphalt pits of bones of the gray fox, the mountain lion, and close relatives of the bobcat and coyote, as well as the condor, which still frequent that region, and thus link the past with the present. The only traces of the ancient vegetation discovered in these asphalt pits are a pine and two species of juniper, which are members of the existing flora. There is reason for believing that primitive man occupied California and other parts of the West during at least the latter part of the period when the fauna of the asphalt pits still flourished. Dr. C. Hart Merriam informs me that the folk-lore of the locally restricted California Indians contains detailed descriptions of a beast which is unmistakably a bison, probably the bison of the asphalt pits.