3io LEISURE-TIME STUDIES. 



manner in which the modifications of body which so per- 

 fectly adapt them for a ground life, have been gained ; and 

 to attain the desired information on this latter point, we must 

 once again study the early history of these fishes. When 

 young and possessing symmetrical bodies, and when the 

 eyes are placed in the natural situation, they may be ob- 

 served to swim through the water in a vertical position, like 

 other fishes ; their flattened surfaces appearing as their sides, 

 and the long dorsal and anal fins bordering the upper and 

 lower margins of the body respectively, whilst the tail fin is 

 set vertically. Soon, however, it is observed that they retain 

 their vertical position in the water with difficulty, owing to 

 the great relative depth of their bodies. Like crank ships, 

 in fact, they have a tendency to become overbalanced ; and 

 there can be little doubt that the small size of the pectoral 

 and ventral fins, together with the absence of a " swimming 

 bladder" or "sound," materially aid in producing this result. 

 Thus unable to swim erect for any length of time, the young 

 flat-fish comes to a natural enough position of rest on its side. 

 Malm's observations now appear to aid our comprehension 

 of the case in a very remarkable degree. This observer tells 

 us that the young fish, as it lies on its side, twists the lower 

 eye upwards as if in the effort to see above; or, in plain 

 language, tries to look round the corner of its own head. So 

 strenuous are these efforts of the young animal, that the eye 

 is pressed with a great degree of force against the upper part 

 of the orbit or eye-cavity, with the result, as Malm testifies, 

 of contracting, in a marked fashion, the forehead or space 

 between the eyes. This observer, indeed, mentions that he 

 has witnessed a young flat-fish elevate and depress the lower 

 eye through a distance corresponding to an angle of seventy 

 degrees. The effect of this frequent muscular exertion on 

 the soft cartilaginous and flexible tissues of the skull of the 

 young fish may readily be imagined. In time, the temporary 

 displacement of the tissues caused by the movements of the 

 lower eye comes to exercise a permanent influence in pro- 

 ducing a decided deformity, and induces the twisting of the 



