196 BULLETIN OF THE BUREAU OF FISHERIES. 



particularly conspicuous. There was no indication of blue. On August 22 it was dark 

 grayish blue, with still some evidence of brown, but not in the stripe bordering the 

 ocular openings. This stripe was now grayish blue. It was put into the green box and 

 compared with specimen adapted to green. Marked contrast between color of the two 

 individuals compared. No indication of green in the specimen adapted to blue. August 

 27, autochromed. Color about same as August 22, brownish tinge " still visible, giving 

 the animal a slightly greenish tint not seen in the other specimen on the dark blue. 



Dark red. — August 2, P. dentatus, 14 cm. long, taken from white aquarium, put 

 into dark red (Bradley's red, shade no. 2). August 12, rich sepia color, not red; there is a 

 tendency to have a row of whitish spots along the fin. Rather prominent white area at 

 the base of the pectoral fin. Three large and several smaller black spots, darker than the 

 rest of the surface and surrounded by yellowish rings, stand out quite conspicuously. This 

 specimen was put into the dark brown and the vermilion boxes and compared with those 

 fully adapted to these colors. It was found to be unquestionably darker than either, but 

 it did not show the slightest indication of any similarity to the color of the skin produced 

 by black. This shows that the relatively long waves of light found in the dark-red color 

 have a specific effect and that the spectrum is probably not shortened at the red end. 

 August 29, color dark rust brown, particularly striking when compared with specimens 

 in boxes of other colors. The pattern was very uniform and inconspicuous, and the 

 tips of fins and tail were yellow. Autochromed and photographed. There was much 

 difficulty in keeping the specimen quiet. It was forcibly held for some time before 

 the autochrome was taken. This caused the skin to become abnormally mottled. The 

 dark patches around the ocelli, shown in figure 70, are due to this. 



Green and yellow. — July 27, P. albiguttus, 15 cm. long, taken from the white 

 aquarium and put into the light-yellow box (Bradley's yellow, tint no. 2). August 11, 

 adaptation very good, very little contrast in different regions of the skin, but uniformly 

 of a slightly darker shade than background. Autochromed, photographed (fig. 56), 

 and put into the green box. The color in all the autochromes taken on light yellow is 

 so faint it can scarcely be seen. 



When first put into the green box there was great contrast in color between this 

 specimen and those adapted to the green. August 12, much darker, color grayish, with 

 distinct greenish tint. In this specimen the green is more pronounced than it is in 

 other specimens in the same box, taken from gray sand several days earlier. August 

 26, very good simulation of background, color yellowish grayish green. The green in 

 the fish becomes very evident when it is compared with specimens adapted to other 

 colors. Autochromed and photographed; colors very faithfully reproduced. (Fig. 



57,71-) 



Vermilion. — ^July 27, P. albiguttus, 19 cm. long, taken from white aquarium and put 

 into vermilion box (slightly darker than Bradley's orange red). July 31, pinkish gray, 

 contrasting strongly with the background. August 12, general appearance when viewed 

 from a distance of 75-100 cm. uniform sepia, contrasting considerably with background. 

 Close examination shows a sort of network consisting of dark-brown stripes about 0.5 mm. 

 wide which surround grayish green areas 1.5 mm. or less in diameter. White patch at 

 the base of the pectoral fin, about 6 mm. in diameter. The three ocelli, characteristic 

 of the species, are dark brown, not black. Put into dark-brown box and compared 



<* This can be distinctly seen in the autochrome taken at this time but not reproduced. 



