120 
ANATOMY AND PHYSIOLOGY 
the eye it forms a thick duplicature, of crescentic form, 
constituting a rudimental third eyelid, not unlike the haw 
of the horse. The globe of the eye is chiefly lodged in 
the soft parts, but little if any of its substance entering 
the bony orbit. It is deeply set within the lids, and 
does not in size much exceed that of an ox. Its size in 
an adult female was c l\ inches in the longitudinal, and 
the same in the vertical direction. The interior, or 
cavity, was l\ inch in each of the last-named directions, 
and its depth two -thirds of an inch only. 
“ The globe at its greatest circumference was 7| inches : 
the transparent cornea, at its transverse or broadest dia» 
meter, measured 1 inch, and in its vertical or narrow- 
est, three-fourths of an inch. The muscles of the globe 
formed a dense mass surrounding the sheath of the optic 
nerve, and were inserted in one continuous line over the 
circumference of the globe at its greatest convexity. 
“ The optic nerve before penetrating the sclerotic is 
continued to some length. It does not exceed the cir- 
cumference of a crow’s quill, but is surrounded by a 
dense fibrous sheath nearly 4 inches in diameter, and 
which, where the nerve perforates the globe, terminates 
on the posterior surface of the latter. Around the globe 
and its muscles much cellular tissue and true fat are 
deposited. The eyeball in shape is not a perfect sphere ; 
"its anterior and posterior surfaces are flattened : that 
portion of the conjunctiva of the globe immediately sur- 
rounding the cornea, and the only portion exposed be- 
tween the aperture of the lids, is of an intense black hue. 
It is possible this dark portion may be a membrane dis- 
