572 BIRD’S-EYE VIEWS, 
es be gained of them, were they merely represented at 
=p omar ete 
at artificially. The sac- 
rifice of Baiar a Daes | is more than compensated for 
by increased perspicuity. 
Recollecting that the “eyeball” e shall continue to 
vall it for convenience sake—is filled with fluid. that presses 
equally in every direction, we cannot at first make out how its 
peculiar shape 
is, maintained. 
But the reason 
why the ball 
does. not as- 
sume a spheri- 
eal shape really 
is plain enough 
when- we. come 
to. dissect. its 
-coats. They 
are partly dony- 
They are splin- 
ted, as it were, 
GARY Mink. me with the bones 
h, h) that are packed alongside each other all around. the 
circumference of one part of the ball. 
e large discoidal segment of a bird’s eye is mostly 
made up of a membrane called the sclerotic, from its bard, 
dense structure. It is'a thick, strong; tough membrane, of 
a glistening livid, or grayish blue color.’ Three” scleroti¢ 
coats or layers, differing from each other a little in texturs 
may be demonstrated by careful dissection, though on super 




Fig. 2. Ve 
b, sclerotie, outer e sao section through middle of eyeball. "e ao 
r. coat; c, sclerotic, middle and inner coats; d, choroid;  B) yaloi 
oration 
supium; 
narn choroid, Ha ornea; k, h, bony sie between layers of sclerotic; i, i, € 
pene , forming ti the ciliary pon sses; k, k, canal of Pet tit; 7, l, iris; ™ 
pecnliar ‘ee psule of lens; o, lens; pi L sie hg chamber. Neither the retina rite 
hing of the optic nerve, wn. The nerve, the marsupium, cor the 
ti f the 
ciliary 
eye i int don not w. weer aS w hb a vertical sec tion throug h the mic iddle © 
figure except artificially. 

