THE AMERICAN NATURALIST. [Vol. XXXVII. 



The lateral line is closely associated with the air, and may also 

 assist at hearing. The ear is an outgrowth from the tubes of the 

 lateral line. As Professor Parker aptly observes, in the skin, the 

 lateral line and the ear, 4i we are dealing with what may be called 

 three generations of sense organs: the skin representing the first 

 generation and giving rise to the lateral line organs, the second, 

 which in turn produce the ears." 



D. S. J. 



Parker on the Optic Nerves of Flounders. 1 — In the bony fishes, 

 the optic nerves pass to the optic lobes of the brain, the one passing 

 to the lobes of the opposite side simply lying over the other, without 

 intermingling of fibres, such as takes place in the higher vertebrates 



According to Parker's observations, in ordinary bony fishes, the 

 right nerve may be indifferently above or below the other. In iooo 

 specimens of ten common species, 486 have the left nerve upper- 

 most and 514 the right nerve. In most individual species, the num- 

 bers are practically equal. Thus, in the haddock, 48 have the left 

 nerve uppermost and 52 the right nerve. 



In the unsymmetrical Teleosts or flounders, and soles, this con- 

 dition no longer obtains. In those species of flounder with the eyes 

 on the right side, 236 individuals representing sixteen species had 

 the left nerve uppermost in all cases. 



Of flounders with the eyes on the left side, 131 individuals repre- 

 senting nine species all have the right nerve uppermost. 



are so common that the species may be described as having the 

 eyes on the right or left side indifferently. In all these species, 

 however, whether dextral or sinistral, the relation of the nerves con- 

 Thus the stony flounder (Platichthys) belongs to the dextral group. 

 Fifty normal specimens, the eyes on the right, have the left nerve 

 dorsal, while the left nerve is also uppermost in 50 reversed exam- 

 ples with eyes on the left. In 15 examples of the California bastard 

 halibut (Paralkhthys cali/ormcus) normally sinistral, the right eye 

 is always uppermost. It is uppermost in 1 1 reversed examples. 



