450 FRANCIS B. SUMNER 



a fairly homogeneous brown or buff tone was commonly assumed. 

 The adaptations of Lophopsetta are not to be compared, however, 

 with such appearances as those exhibited by Rhomboidichthys. 

 The rich mosaic effect sometimes displayed by the Mediter- 

 ranean species would seem to be structurally impossible in the 

 American one. As a compensating advantage, from the experi- 

 menter's point of view, the latter may be obtained in far greater 

 numbers. 



The experiments with this fish were nearly all performed in the 

 cod-hatching boxes of the Woods Hole station. These are wooden 

 boxes, with a bottom area of 30 x 70 centimeters, and containing 

 water to a depth of 18 centimeters. They are built in rows of 12 

 each. In the course of the present investigations, they were 

 painted variously, as will be described in connection with the 

 separate experiments. No photographs of Lophopsetta were 

 taken. 



Blotched surfaces 



A few experiments were tried to test the capacity of this 

 species to adapt itself to a highly contrasted pattern. Four speci- 

 mens were placed (two at a time) in one of the boxes just de- 

 scribed, the walls and bottom of which had been painted white 

 with small irregular daubs of black scattered throughout the entire 

 surface. All of these fishes responded unmistakably to this 

 stimulus, the ground-color becoming (or remaining) medium pale, 

 while certain stellate or irregular black blotches came distinctly 

 into view. The fishes thus acquired a piebald appearance, quite 

 different from anything which was observed o: a background of 

 uniform shade. 



Another interesting case was noted, in which these dark blotches 

 appeared upon an extremely pale specimen which had been kept 

 for three days in a box having white (unspotted) walls and bottom. 

 It was found, in this instance, that patches of very dark vegetable 

 debris had accumulated at the bottom of the box in the neighbor- 

 hood of the fish's head. Removal of this debris resulted in the dis- 

 appearance of the spots, while a later accumulation led to their 

 return. It must be remarked, however, that in the specimen under 



