292 MISCELLANEOUS OBJECTIONS TO THE [Chap. VII. 



figure. Malm states that the newly-hatched young of 

 perches, salmon, and several other symmetrical fishes, 

 have the habit of occasionally resting on one side at the 

 bottom ; and he has observed that they often then strain 

 their lower eyes so as to look upwards ; and their skulls 

 are thus rendered rather crooked. These fishes, however, 

 are soon able to hold themselves in a vertical position, 

 and no permanent effect is thus produced. With the 

 Pleuronectida?, on the other hand, the older they grow 

 the more habitually they rest on one side, owing to the 

 increasing flatness of their bodies, and a permanent effect 

 is thus produced on the form of the head, and on the 

 position of the eyes. Judging from analogy, the tendency 

 to distortion would no doubt be increased through the 

 principle of inheritance. Schiodte believes, in opposi- 

 tion to some other naturalists, that the Pleuronectidae 

 are not quite symmetrical even in the embryo ; and if 

 this be so, we could understand how it is that certain 

 species, whilst young, habitually fall over and rest on 

 the left side, and other species on the right side. Malm 

 adds, in confirmation of the above view, that the adult 

 Trachvpterus aivticus, which is not a member of the 

 Pleuronectidae, rests on its left side at the bottom, and 

 swims diagonally through the water ; and in this fish, 

 the two sides of the head are said to be somewhat dis- 

 similar. Our great authority on Fishes, Dr. Giinther, 

 concludes his abstract of Malm's paper, by remarking 

 that " the author gives a very simple explanation of the 

 abnormal condition of the Pleuronectoids." 



We thus see that the first stages of the transit of the 

 eve from one side of the head to the other, which Mr. 

 Mivart considers would be injurious, may be attributed 

 to the habit, no doubt beneficial to the individual and 



