32 Acknowledgments are due to Lord Avebury and Messrs. Williams and Norgate for their kind permission to reproduce figs. 10-17 from Prehistoric Times; to Prof. Boyd-Dawkins for figs. 1 and 7 from Early Man in Britain, and to Mr. Worthington Smith for the use of fig, 20, and other blocks which have previously appeared in the publications of the Essex Field Club. LIST OF BOOKS USEFUL TO STUDENTS. " Prehistoric Times" .. .. Lord Avebury .. Williams & Norgate. " Early Man in Britain " .. W. Boyd Dawkins Macmillan. " Ancient Stone Implements" .. Sir John Evans .. Longmans. " Ancient Bronze Implements " .. Sir John Evans .. Longmans. "British Barrows" .. .. Canon Greenwell.. Clarendon Press. " The Lake Dwellings of Europe " ... Dr. Munro .. Cassell & Co. " Man the Primaeval Savage" .. G. Worthington .. Ed. Stanford. Smith "The Civilisation of Sweden" .. Mountelius .. Macmillan. "Anthropology" .. .. Tylor .. Macmillan. " The Study of Man " .. .. Prof. A. C. Haddon. Murray. The " Transactions of th? Essex Field Club " and the " Essex Naturalist " contain many papers indispensible to the student and future explorer. First picture of a Dene-hole (at Tilbury, Essex.) From Holland's Britannia, 1610.