PLATE XI 



The Irides of Birds 

 (Ida Mann) 



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Fig. 1. — Jackdaw (albino), Coloslus monedula. 



Fig. 2. — Pigeon, Columba. 



Fig. 3. — Duck. Dendrocygna. 



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Fig. 4. — Uock-ho]j -r penguin, Eudyptes FiG. 5. — Scops owl, Otus bakkanice.na. 



cr :itliis. 



A, zone of radial veins and deep circumferential arteries: B, sphincteric plexus; 

 G, avascular circumpupillary zone; D, diagrammatic section through iris. a, artery; 

 c, plexus ; v, vein. 



t To face p. 407. 



so. — VOL. I 



