which the bones were found, and, in consequence thereof, the age of the bones themselves has been the subject of not a little discussion, and of wide differences of opinion. Already the literature of the subject is considerable, and the reader who chooses may find it in the discussions by Professors Winchell and Upham, in Science and the American Geologist, by Professor Chamberlin, in the Journal of Geology, and, more recently, by Dr. Holmes, in the American Anthropologist. The subject, too, has been fully discussed at the Congress of Americanists in New York, and at the various meetings in Washington during the session of the American Association for the Advancement of Science. It is fortunate that the conditions were such that there can be no
View looking Northward across the Mouth of the Tributary Valley. showing Concannon's house at the left and the truncated slope under it, the mouth of the valley just beyond, and in the center the north bluff with its truncated face overlooking the Missouri bottoms, on the edge of which the railroad lies. The bluff is about 160 feet high. From a photograph by Mr. Chamberlin.
serious doubt concerning either the discovery itself or the nature of the remains. The small ravine, near the mouth of which the bones were discovered, opens upon the flood-plain of the Missouri River from the west. The ravine is less than a mile in length, with a fall of more than one hundred feet, and has no running stream, save perhaps for a short time in wet weather. Very near its mouth it has a tributary branch, perhaps a quarter of a mile in length, coming from the south, nearly parallel with the river bank. It is at the extremity of the intervening spur that the excavation was made, beginning a few feet above the bed of the ravine and extending southward nearly horizontally for a distance of seventy feet. The cave itself has for its floor in its whole
