Instincts, Habits, and Adaptations 



'75 



the eyes and the brain, caused by the growth of the facial carti- 

 lages. 



5. The migrating eye moves through an arc of about 120 

 degrees. 



FIG. 128. Platophrys lunatus (Linnaeus), the Wide-eyed Flounder. Family 

 Pleuronectidce. 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 influ- 

 enced by the twisting as the 



ocular region. .- .^ 



8. The location of the olfac- 

 tory nerves (in the adult) shows FIG. 129. Young Flounder, just 

 that the morphological midline hatched, with symmetrical eyes. 

 f 11 ,- , i , 1 (After S. R. Williams.) 



follows the mterorbital 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 meta- 

 morphosis in the sinistral fish is parallel to that in the dextral 

 fish. 



1 1 . The original location of the eye is indicated in the adult 

 by the direction first taken, as they leave the brain, by those 

 cranial nerves having to do with the transposed eye. 



