The results of many years' search and inquiry are included in this paper, which is supplementary to the account of the Caddington palaeolithic ‘floor’ given in the author's Man the Primeval Savage (1894). The deposit has now been recognized in Hertfordshire and Bedfordshire, Caddington beingformerly divided between the two counties; and the discoveries here to be described must be regarded as originally connected with the Caddington ‘floor’, though the three sites are now isolated hills separated by rivers that have formed, and considerably deepened, their channels since man was living in the neighbourhood during the formation of the brick-earth. The two new sites are dealt with separately, and as far as possible on similar lines, so as to facilitate comparison.