ADJUSTMENT OF FLATFISHES 449 



condition) had, to a considerable extent, reappeared. Subsequent 

 experiments with this fish led to the suspicion that enough light 

 still passed through the corneas to influence the changes. After 

 complete extirpation of the eyes, the fish, which was finally re- 

 turned to the marble-bottomed tank, remained "rusty brown, 

 with inconspicuous markings." 



4. LOPHOPSETTA MACULATA 



Since certain important points were left in an unsatisfactory 

 state by the experiments at Naples, this line of work was resumed 

 during the following summer in the laboratory of the Bureau of 

 Fisheries at Woods Hole. The fish which was chiefly employed 

 in these later experiments was the common Vindow-pane' or 

 'sand-dab,' Lophopsetta maculata (Mitchill), another member of 

 the turbot group. Lophopsetta proved to be a far less favorable 

 object for studies of this sort, since, on a white surface, it never 

 attained such an extreme degree of pallor as did Rhomboidich- 

 thys, and its capacity for displaying adaptive skin patterns, though 

 far from wanting, was much more restricted.^'' The experiments 

 with this species were therefore concerned chiefly with the rela- 

 tive influence of different portions of the visual field, the time of 

 reaction, effect of blinding, etc. Especial attention was likewise 

 given to the problem of how the fish is able to conform the shade 

 of its skin to that of its background, irrespective of the degree of 

 illumination. 



A few experiments with natural bottoms (gravel and sand) 

 were also tried, but without any very striking results. In the large 

 exhibition aquaria the adaptive reactions were, however, some- 

 times rather impressive. Some specimens assumed a character- 

 istic appearance upon gravel, which was decidedly different from 

 that displayed upon sand, and the changes were sometimes fairly 

 rapid. Upon the former material, spots, both light and dark, 

 came into view rather conspicuously, while upon the latter, 



^ Indeed, of the nine species of Pleuronectidae and Soleidae which have been 

 observed by the writer, Rhomboidichthys podas appears to possess by far the 

 highest capacity for adaptive changes of this sort. 



THE JOURNAL OF EXPERIMENTAL lOOLOGY, VOL. 10, NO. 4 



