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THE EYE IN EVOLUTION 



Figs. 492 and 493.— The Avian Eye. 



Fig. 492. — Diagram of the eye of a bird. 



A, annular pad ; BM, Briicke's muscle ; CC, ciliary cleft ; Ch, choroid 

 MC, muscle of Crampton ; ON, optic nerve ; P, pecten ; 8, scleral cartilage 

 Sc, sclera ; SO, scleral ossicles ; TL, tenacular ligament. 



Fig. 493. — The eye of the domestic chicken (Norman Ashton). 



