Defcription of the Eye of the Seal. 477 



fomewhat enlarged as it paffed through the fcle- 

 -rotis, and was again contradled in its paflage 

 through the choroides. In the former part, the 

 diameter of the nerve was -oi? of an inch; in the 

 latter -06. 



Upon meafuring carefully the different arcs of 

 of the circumference of the eye, taken from the 

 optic nerve to the center of the pupil, it was 

 found that the nerve was placed at the diftance 

 of "I I of an inch from the axis of the pupil. 

 And as the axis of the pupil muft be in the cen- ' 

 ter of that area on which the pidlure is formed, 

 the diameter of the area on which a pifture may 

 be formed in the eye of a feal is "II, or nearly a 

 quarter of an inch, of the retjna, excluding the 

 breadth of the optic nerve. 



The quantity of fibrous fubftance accompany- 

 ing the optic nerve in this animal, the fpreading 

 out of that fubftance, with the fmallnefs of the 

 nerve itfelf, feem to have been the caufes of that 

 deception, which fome incautious naturalift has 

 fallen into, and which has been propagated by 

 the different authors who have copied one ano- 

 ther on this fubjeft. * 



The fmallnefs of the pupil in this animal is 

 very remarkable. What there is in the habits of 

 a feal to require this ftrufture, I cannot tell. It 

 feems a general law of nature, that the pupil of 

 the eye becomes dilated at death. But unlefs 

 this law be reverfed with refpeft to the feal, its 

 T 3 eye 



