13-Paralichthys albiguttus, Individual (B) on a smooth white background continuously from July 23, 2 p.m., to July 25, 10 a.m. It was alternately on white and on black about equal time during the preceding seven days. The skin actually appeared much whiter and less mottled and the animal less conspicuous than the photograph indicates. This is partly due to the shadow in the background along the ventral side. In specimens kept continuously on white for two months the skin became much more uniformly white. 14- Individual (B) on black and white background (circles 5 mm. in diameter) from August 11, 12 m., to August 13, 1:30 p.m... 15- Individual (B) on black and white background 2 cm. squares from August 24, 11 a.m., to August 27, a.m., after having been adapted to white... 16- Individual (B) on black and white background (circles 5 mm. in diameter) from August 15, 10 a.,m., to August 16, 9 a.m. This photograph shows one of the most remarkable concealing patterns observed. The fish appeared to contain numerous holes..