692 Suborder Heterosomata 
generally, the process takes place at an earlier stage than in 
Platophrys. 
Optic Nerves of Flounders.—In the Bulletin of the Museum of 
Comparative Zoology (Vol. XL, No. 5) Professor George H. 
Parker discusses the relations of the optic nerves in the group 
of flounders or flatfishes. 
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 fibers, 
such as takes place in the higher vertebrates and in the more 
primitive fishes. 
According to Parker’s observations, in ordinary bony fishes 
the right nerve may be indifferently above or below the other. 
In tooo specimens of ten common species, 486 have the left 
nerve uppermost and 514 the right nerve. In most individual 
species the numbers are practically equal. Thus, in the had- 
dock, 48 have the left nerve uppermost and 52 the right nerve. 
In the unsymmetrical teleosts or flounders, and soles, this 
condition 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, 
representing nine species, all have the right nerve uppermost. 
There are a few species of flounders in which reversed 
examples are so common that the species may be described 
_ TE as having the eyes on the right 
SSS = oO left side indifferently. In all 
Tae these species, however, whether 
Tic. 595.— Young Flounder, just Gextral or sinistral, the relation 
ee He aera °yes- of the nefves conforms to the 
type and is not influenced by 
the individual deviation. Thus the starry flounder (Platich- 
thys) belongs to the dextral group. In 50 normal specimens, 
the eyes on the right have the left nerve dorsal, while the 
left nerve is also uppermost in 50 reversed examples with eyes 
on the left. In 15 examples of the California bastard halibut 
(Paralichthys californicus), normally sinistral, the right eye is 
always uppermost. It is uppermost in 11 reversed examples. 
Among the soles this uniformity or monomorphism no 
