No. 3.] 
pre. 
prs. 
prs. 
prs. 
prs. 
prs. 
prs. 
prs. 
prs. 
VISUAL CELLS INVERTEBRATES. 
nl., nuclear process. 
dst., outer segment. 
dst. bac., outer segment of rod. 
dst. con., outer segment of cone. 
dst. con. dst., outer segment of far cone. 
dst. con. prx., outer segment of near cone. 
prx., inner segment. 
prx. bac., inner segment of rod. 
prx. con., inner segment of cone. 
st. nl. ex., outer nuclear layer. 
st. nl. m., middle nuclear layer. 
st. pig., pigment layer. - 
st. ret. ex., outer reticular layer. 
vac., 
vsl., 
vacuole. 
vesicle. 
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