The knowledge of husbandry, though rude, and the possession of domestic animals, though of a few species only, strikingly indicate the advance over the Paleolithic tribes. They also had fixed places of living. This culture spread all over Europe. That it was substantially the same everywhere there is no doubt. Certain refuse heaps in Denmark, Scotland, and indeed in all the sea-coast countries, have been thought to support a different conclusion. Those of Denmark have been very carefully studied, and so we will refer to them. All along the Baltic coast, but especially in Denmark, have been discovered great numbers of mounds, which were found to consist “almost entirely of shells, especially of the oyster, broken bones of animals, remains of birds and fishes, and, lastly, some wrought flints.” The first supposition in regard to those shell-heaps was that they were of marine formation, accumulated beneath the sea, and elevated to the surface along with the gradual rise of the land. But they are now known to be nothing more or less than the sites of ancient settlements. The location of the rude cabins can still be traced. The ancient hearths are still in place. “Tribes once existed here who subsisted on the products of hunting and fishing, and threw out around their cabins the remains of their meals, consisting especially of the _débris_ of shell-fish.” These heaps gradually accumulated around their rude dwellings, and now constitute the refuse heaps in question.24 The careful investigation of their contents has failed to disclose any evidence of a knowledge of agriculture, and the only domestic animal found is the dog. The implements are altogether of stone and horn. No trace of metal has yet been obtained. As a rule, they are rudely made and finished. Though of the Neolithic type, they are not polished except in a few instances. The principal interest turns on the question of age of these refuse heaps. Some think they were accumulated at the very beginning of the Neolithic Age—that these tribes preceded by many years the men of the Swiss Lakes. Others think they were tribes of the same great people, living at the same time. On such a point as this, only those who have carefully studied the deposits are entitled to speak.