A Guide to the Study of Fishes, Volume 1 (of 2)

by David Starr Jordan

Fig. 126.

Fig. 127.

Figs. 126, 127.—Larval stages of Platophrys podas, a flounder of the Mediterranean, showing the migration of the eye. (After Emery.)

In a recent study of the migration of the eye in the winter flounder (Pseudopleuronectes americanus) Mr. Stephen R. Williams reaches the following conclusions:

1. The young of Limanda ferruginea (the rusty dab) are probably in the larval stage at the same time as those of Pseudopleuronectes americanus (the winter flounder).

2. The recently hatched fish are symmetrical, except for the relative positions of the two optic nerves.

3. The first observed occurrence in preparation for metamorphosis in P. americanus is the rapid resorption of the part of the supraorbital cartilage bar which lies in the path of the eye.

4. Correlated with this is an increase in distance between the eyes and the brain, caused by the growth of the facial cartilages.