But to return to undoubted neolithic skulls, we have very clear evidence that the four distinct European races already existed. Thus in Britain we have two distinct forms of barrows or burial tombs, one long, the other round, and it has become proverbial that long skulls go with long barrows, and round skulls with round barrows. The long barrows are the oldest, and belong entirely to the stone age, no trace of metal, according to Canon Greenwell, having ever been found in them. The skulls and skeletons are those of a long-headed, short, and feeble race, who may be identified with the Iberians; while the round barrows contain bronze and finally iron, and the people buried in them were the tall, fair, round-headed Gauls or Celts of early history, or intermediate types between these and the older race. Later came in the tall, fair, and long-headed Anglo-Saxon and Scandinavian races, so that we have three out of the four European types clearly defined in the British islands and traceable in their descendants of the present day. But when we attempt to go beyond the Iberians of the neolithic age in Britain, we are completely at fault. We have abundant remains of palæolithic implements, but scarcely a single undoubted specimen of a palæolithic skeleton, and it is impossible to say whether the men who feasted on the mammoth and rhinoceros in Kent's cavern, or who left their rude implements in the high-level gravel of the chalk downs, were tall or short, long-headed or round-headed. On the contrary, there seems a great hiatus between the neolithic and the palæolithic periods, and, as Geikie has shown, this appears to be the case not in England only but in a great part of Europe. It would almost seem as if the old era had disappeared with the last glacial period, and a completely new one had been introduced. But although the skulls and bones of palæolithic races are wanting in Britain and scarce everywhere, enough of them have been found in other European countries to enable anthropologists not merely to say that different races already existed at this immensely remote period, but to classify them by their types, and see how far these correspond with those of later times. This has been done especially in France and Belgium, where the discoveries of palæolithic skeletons and skulls have been far more frequent than elsewhere. Debierre in his _L'Homme avant l'histoire_, published in the _Bibliothèque Scientifique_ of 1888, enumerates upwards of forty instances of such undoubted Quaternary human remains, of which at least twenty consisted of entire skulls, and others of jaws and other important bones connected with racial type. The best and latest conclusions of modern anthropology from these remains will be found in this work of Debierre's, and in Hamy's _Palæontologie humaine_, Quatrefages' _Races humaines_, and Topinard's _Anthropologie_, and it will be sufficient to give a short summary of the results.