ALBINISM and ambicoloration, common abnormalities in the coloration of flatfishes, are not unusual in those species of Platichthys found on the European coast from the White Sea to the Straits of Gibraltar, and throughout the Mediterranean Sea and its subdivisions. But, so far as I know, ambicoloration has never before been described in P. stellatus, which ranges the North Pacific from southern California to Japan. Recently an interesting totally ambicolorate specimen was sent to me by Dr. Carl L. Hubbs, who collected it in Alaska, where it had been caught 15 or 20 miles off Petersburg. As it lies before me, this flounder measures about 12.5 inches. Before dissection and shrinkage from preservation, it probably measured about 13.5 inches over all. The normal weight of course cannot be ascertained, but, since the fish attains a weight of 15 to 20 pounds, this specimen is plainly a young one. It is a true ambicolorate flounder, being as dark on the left or lower side as it is on the right or upper side. Furthermore, the dark bars and splotches of the right side are almost identically reproduced on the left. This is the most perfectly ambicolorate flatfish I have ever examined. It is most unfortunate that, in the process of cleaning the fish for freezing, the head and abdomen had been cut up badly. This of course makes it impossible to have a photograph or a drawing made. Fortunately, however, the left or rotating eye escaped the knife. This eye is barely over the median ridge. Indeed its outer or left edge is barely clear on the right of the median line. This incompletely rotated eye has produced the other always associated deformity-the hook at the anterior point of the dorsal fin. Either the hooked point got its final growth settled while the eye was migrating across the mid-dorsal line, or else the incompletely rotated eye in its permanent position just across this line inhibited any further forward and downward growth of the interior part of this median fin. It must be emphasized that total ambicoloration in flatfishes is always accompanied by a dorsal fin hooked at the anterior part and by an incompletely rotated eye. However, these head anomalies may occur with only partial ambicoloration, but so far as I know they are never present unless there is partial coloration below. Fortunately I have been able to study a series of flounders showing perfect gradation from very little color on the lower side to the perfect condition of ambicoloration called "black belly." Every one of these fish, from the least colored to those completely dark on the under side, had a hooked dorsal and an incompletely rotated eye. Thus Gudger and Firth in 1936 described a Paralichthys oblongus having the hinder two-fifths of the lower side colored like the upper side but lacking head anomalies. Another fish of the same species had the head anomalies but only about one-fifth (the extreme hinder part) of the lower surface colored. Another with the head anomalies had the hinder two-fifths of the lower side colored like the upper. In 1935 they described a halibut, Hippo-