5. The migrating eye moves through an arc of about 120 degrees.
Fig. 128.—Platophrys lunatus (Linnæus), the Wide-eyed Flounder. Family Pleuronectidæ. Cuba. (From nature by Mrs. H. C. Nash.)
6. The greater part of this rotation (three-fourths of it in P. americanus) is a rapid process, taking not more than three days.
7. The anterior ethmoidal region is not so strongly influenced by the twisting as the ocular region.
Fig. 129.—Young Flounder, just hatched, with symmetrical eyes. (After S. R. Williams.)
8. The location of the olfactory nerves (in the adult) shows that the morphological midline follows the interorbital septum.
9. The cartilage mass lying in the front part of the orbit of the adult eye is a separate anterior structure in the larva.
10. With unimportant differences, the process of metamorphosis in the sinistral fish is parallel to that in the dextral fish.