other quality of implements. Classification of tribes and races in a time-scale, or even in a culture scale, according to the kind of stone implements they used, is impossible. The Pai Ute and the Iroquois made equally good tools in the seventeenth century, while in other lands still inferior tribes were making implements about as good, and others were struggling on with poorer ones. At the time of the Aztec confederacy, their stone tools were not greatly superior to those of the Pai Ute. Therefore, it would seem that any resemblance between so-called American “paleolithic” implements and modern stone implements cannot be used as an argument to disprove the age of the former, nor that a polished stone implement found in a supposed ancient gravel is necessarily an indication of intrusion or that the gravel is not ancient. The implements thus far found in the California auriferous gravels have been similar to those found on the surface to-day, and this has been held by some to be a suspicious circumstance. It is not. Some tribes in California in those remote times were probably making stone implements quite as good as anything made to-day. Stone-working is not capable of high development. The range is limited. Some tribes compassed it early. Because also we do not find stone implements abundant in the North-American glacial drift proves nothing concerning man’s condition, presence or absence on the continent at that time. The population _was almost entirely below the glacial limit_, only a few inferior tribes skirting its southern fringe. We should, then, expect to find few northerly pre-glacial evidences,[392] as the main culture development took place south of the ice line, and tribes above this in pre-glacial times would be the most primitive. [Illustration: TLINKIT SUMMER CAMP From photograph by the Harriman Alaska Expedition, 1899 ] [Illustration: ESKIMO SUMMER CAMP, PORT CLARENCE From photograph by the Harriman Expedition, 1899 ] [Illustration: WOODEN SNOW GOGGLES OF THE CENTRAL ESKIMO]