148 



VERTEBRATE ZOOLOGY 



which he calls Heterosomata. The Flounders are bottom-fishes that 

 lie on the side instead of on the belly as do most other bottom-fishes; 

 some species lie on the right, others on the left side. To adapt them- 

 selves to this position there is a remarkable twisting of the cranium 

 that results in bringing both eyes on the same side of the head, and 

 makes the whole region of the head decidedly asymmetrical. The 

 upper side of the body becomes variously pigmented in harmony 

 with almost any background; experiments, involving the use of the 



FIG. 88. The Shark Sucker, Remora brachyptera, Lowe (above). (From Jordan 

 and Evermann.) 



FIG. 89. Sucking disc of Remora brachyptera, Lowe (below). Dorsal view. 

 (From Jordan and Evermann.) 



most elaborate of artificial backgrounds, having proven their ex- 

 traordinary capacity for imitation. The lower side normally remains 

 unpigmented, but, if it is artificially illuminated by growing the fishes 

 on an elevated glass floor in an aquarium, it acquires an appearance 

 much like the upper side. The young flounder is bilaterally symmet- 

 rical and begins the head-twisting process some time before it takes 

 up the bottom-living habit. Flounders are believed to have been de- 

 rived from some one of the high compressed types, which adopted the 

 bottom-feeding habit and was forced to modify itself in a peculiar 

 way to meet the new conditions. 



