COLOR CHANGES AND ADAPTATION IN FISHES. 1 83 



After completing this section some observations were made which throw consid- 

 erably more light on the question of modification in beha\dor. On September 21, 

 9 a. m., four large specimens of P. alhiguttus were taken from the aquaria in the labora- 

 tory, where they had been for over three months, and set free in a small tide pool. All 

 four immediately came to rest on the bottom, but none of them bedded. This is very 

 unusual. Flounders, under such conditions, ordinarily bed at once. At 10 a. m. 

 each one was still in precisely the place where it came to rest. The tide was at this 

 time ebbing and the water in the pool was rapidly running out. One of the flounders 

 was stimulated with a stick and driven out of the pool. After leaving the pool it swam 

 about 20 meters and came to rest on the sand in about 15 cm. of water, but it did not 

 bed. Another specimen was then stimulated. It swam about i meter and came to 

 rest without bedding. It was again stimulated, after which it again swam a short dis- 

 tance, but this time it bedded when it came to rest. The bedding reaction, however, 

 was so feeble that only the edges of the fins became covered with sand. Thereafter 

 this specimen bedded every time that it came to rest, but none of the other specimens 

 gave this response. The water in the tide pool h;id in the meantime become so low 

 that the remaining two specimens could no longer swim out. Both were caught and 

 carried out. All four specimens were now lying on the sand in shallow water, one 

 bedded and three not. Half an hour later all four were found stranded on the beach. 

 None had moved as the tide ebbed until it was so low that they could not get away. 

 They had so completely forgotten the ways of the sea that all would have perished 

 had they not been rescued. They were carried out and thrown into water about 30 

 cm. deep and left. 



At low tide another observation was made, but only one specimen was found. All of 

 the others had evidently gone out with the tide. This one, however, the only one which 

 had given the bedding reaction, failed to get out and was found dead under a board. 

 It apparently had become so accustomed to stimulation in the aquarium, where it was 

 daily stroked and handled, that it failed to respond when the board sank with the ebbing 

 tide, until it was too late. It had obviously completely forgotten the danger of the tides. 

 These observations show in a striking way that the responses of these animals to given 

 stimuli can be greatly modified. 



Flounders in general are relatively quiet, especially during the daytime, when they 

 frequently lie quiet for hours at a time. One specimen, after having been in an aquarium 

 in the laboratory for several days, was observed to remain in a given position, without 

 the slightest noticeable change, from 8 a. m. until nearly 6 p. m. Many others were seen 

 to remain quiet for shorter periods, both in the laboratory and outside. In aquaria 

 which do not contain any soil they tend to huddle together and partly cover each other 

 (pi. xxxvii). 



During the night, however, they are much more active. This is true, at least, for 

 specimens kept in captivity. After dark considerable noise usually came from the 

 aquaria. Ancylopsetta particularly has a tendency to jump out of the water. On 

 several occasions, during the night, specimens jumped out of an aquarium, the sides of 

 which extended 8 inches above the surface of the water. 



Fishermen report that flounders often take pieces of meat of various sorts, but that 

 they usually feed on Crustacea, mollusks, and minnows; that they usually lie concealed 

 on the bottom until their prey gets within range, then suddenly spring and seize it. 



