I HOPE I may be allowed to call myself an archaeologist, although a very humble one, yet I find myself in complete disagreement with my friend Mr. Reid Moir in NATURE of December 30, p. 1006. After C. J. Thomsen1 had in 1836 revived the idea of Lucretius2 and divided the past history of man into the three ages of stone, bronze and iron, there was one stone age, but when the discoveries of Boucher de Perthes had been recognised by English savants, Sir John Evans3 in 1859 pointed out that this age must be divided into two, that in which the fauna was extinct and that in which it was recent. Later on, Sir John Lubbock4 suggested that these two periods should be termed respectively the palaeolithic and neolithic ages. It was soon noted, however, that these ages did not pass into one another, but that between them there was a great gulf fixed, and this became known as the great hiatus.