Thus little or nothing is known of the first inhabitants of Celtic lands, beyond their tools, but when we come to the middle palæolithic period the case is different. While some difference of opinion still exists, the view advanced by Obermaier[10] and others seems to be gaining ground, that in Celtic lands the industry of Le Moustier first appeared as the climate was becoming colder on the approach of the last or Würm glaciation, though it is thought by some that it had flourished in an earlier and warmer time in the regions lying to the east.[11] This industry is believed by most authorities to have survived the first Würm maximum and to have lasted through the temporary amelioration of the Laufen retreat. Whether it survived, too, the second maximum, and lasted until the climate definitely improved is more doubtful, but many archæologists of great repute believe that it did so,[12] and unless this was the case it will be difficult to explain certain features of the Audi flints.[13] Though there is as yet no general agreement as to the duration of the Mousterian industry, it is different when we come to consider the type of man who was responsible for this work. Everyone is agreed that the authors of this culture were of the type known as Neanderthal man, for several skeletons of this type, or parts of them, have been found associated with flint implements of Le Moustier design, and none have as yet turned up under conditions which make this correlation impossible.[14] A considerable number of skulls and skeletons, about two dozen in all, of Neanderthal man have been found, the great majority in Celtic lands; but, though there is a general resemblance between all the members of the series, sufficiently strong to mark them off from the Piltdown skull on the one hand and from modern men on the other, the type is in many respects very variable. There are vast differences observable between the skull from Chapelle-aux-Saints,[15] the highest form yet discovered, and that of the Gibraltar man,[16] or rather woman, which is the most primitive yet found in Europe. As far as one can judge from the descriptions which have appeared as I write, the skull recently found at Broken Hill in Rhodesia differs from that of Gibraltar hardly if at all more than the Gibraltar skull differs from that found at Chapelle-aux-Saints. In the latter case there are several intermediate forms, in the former such may yet turn up, for Africa has, as yet, produced but one other skull of this type, that found not long ago near Constantine in Algeria, no description of which has, I believe, yet been published.