Fishes . Fig. 56. 0~ ~^^ « 7 ^ ^s^^/l 1. ,^ :^ Fig. o7. Figs. 56, 57.—Larval stages of PZa^op/jrys porfas, a flounder of the Mediterranean, showing the migration of the eye. (After Emery.) flotmder {Pseiidopleuronectes americanus) Mr. Stephen R. Wil-liams reaches the following conclusions: 1. The young of Limanda fernigiiiea (the rusty dab) areprobably in the larval stage at the same time as those of Pseii-dopleuronectes americanus (the winter flounder). 2. The recently hatched fish are symmetrical, except for therelative positions of the two optic nerves. 3. The first observed occurrence in p
Fishes . Fig. 56. 0~ ~^^ « 7 ^ ^s^^/l 1. ,^ :^ Fig. o7. Figs. 56, 57.—Larval stages of PZa^op/jrys porfas, a flounder of the Mediterranean, showing the migration of the eye. (After Emery.) flotmder {Pseiidopleuronectes americanus) Mr. Stephen R. Wil-liams reaches the following conclusions: 1. The young of Limanda fernigiiiea (the rusty dab) areprobably in the larval stage at the same time as those of Pseii-dopleuronectes americanus (the winter flounder). 2. The recently hatched fish are symmetrical, except for therelative positions of the two optic nerves. 3. The first observed occurrence in preparation for meta-morphosis in P. americanus is the rapid resorption of the partof the supraorbital cartilage bar which lies in the path of theeye. 4. Correlated with this is an increase in distance between 76 Instincts, Habits, and Adaptations the eyes and the brain, caused by the growth of the facial carti-lages. 5. The migrating eye moves through an arc of about Fig. 58.—Platophrys hinatus (Linnaeus), ths Wide-eyed Flounder. FamilyPleuronectidw. Cuba. (From nature by Mrs. H. C. Nash.) 6. The greater part of this rotation (three-fourths of it inP. americanus) is a rapid process, taking not more than threedajs. 7. The anterior ethmoidal region is not so strongly influ-enced by the twisting as theocular region. 8. The location of the olfac-tory nerves (in the adult) showsthat the morphological midlinefollows the interorbital septum. 9. The cartilage mass lying in the front part of the orbit ofthe adult eye is a separate anterior structure in the lana. 10. With unimportant differences, the process of meta-morphosis in the sinistral fish is parallel to that in the dextralfish. 11. The original location of the eye is indicated in the adultby the direction first taken, as they leave the brain, by thosecranial nerves having to do with the transposed eye. Fig. 59. — Young Flounder, justhatched, with symmetrical eyes.(.\fter S. K. Williams.) Instin
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