In a previous paper (Journ. Mar. Biol. Assoc., Vol. XVII, No. 1, Sept., 1930) I described in detail a series of experiments on Growth and Maintenance in the Plaice which were carried out during 1928 and 1929 at Cawsand, near Plymouth, and at Lympstone, near Exmouth. The purpose of the present paper is to present and discuss data collected at the above places during 1930 in continuing the experiments. The conditions under which the last experiments were carried out were identical with those of 1929, i.e. refined with reference to those of 1928. Several additions were made, however, to the series of 1929. Two fish of each sex were supplied with maximum rations while living under the conditions maintained during 1928 and were segregated in a box, which had the original ½″ mesh wire-netting windows but which was divided up into compartments. This experiment was arranged in order that we might ascertain the possibility of food leakage due to tidal action during the course of the earliest experiments, but it also enables us to compare the results obtained under slightly different conditions of water circulation, which is important in view of the fact that the windows of the modified boxes were of necessity minimal in area.