5-Paralichthys albiguttus, on very fine gray sand, almost entirely covered with sand, from August 19 to 21. Note the two small depressions in the sand at the base of the caudal fin. The lower one is much more prominent than the other. This individual breathed only through the lower gill. The water which entered the mouth passed back under the body and oozed up through the sand, forming the depressions. The animal was very effectively concealed. 6-Same individual uncovered.... 7- Paralichthys, 13 cm. long, in a glass dish over very fine black sand. Note the remarkable similarity between the pattern and the shade in the fish, especially the central part of the body, and those of the sand. The tips of the fins and the tail have no pigment and consequently stand out boldly against the background. 8- Paralichthys albiguttus, 16 and 10 cm long, on a smooth jet black background. Note the conspicuous white spots. In some instances all of these, except a trace of the one at the base of the pectoral fin, disappeared entirely.