RETINAL STRUCTURE AND VISUAL ACUITY 99 



be more highly developed than the former. The highly 

 developed nasal fovea centralis of the hawk, and the double 

 fovea of the swallow are shown respectively in Figures 67, 69. 



Fig. 70 (Left). InfuJamacular fundus of the Greater YeJlow-legs (Totanus 

 melanoleucus) showing band or ribbon-like area with single central fovea. 

 (From figure 114, The Fundus Oculi of Birds, Casey Wood, 1917. Lakeside 

 Press, Chicago.) 



Fig. 71 (Right). Infulabimacular fundus of the Old World flamingo (Phoeni- 

 copterus roseus) showing two macular regions. (From figure 115, Casey Wood, 

 1917.) 



Fig. 72 (Left). Fundus oculi of the American crow (Corvus americanus) 

 showing single central fovea. (From figure 142, Casey W^ood, 1917.) 



Fig. 73 (Right). Fundus oculi of the European barn owl (Strix flammea) 

 showing single temporal fovea. (From figure 112, Casey Wood, 1917.) 



Wood (op. cit.) and Slonaker (1897) pointed out that in 

 birds with a single fovea, this structure is generally placed 

 about the center of the retina, slightly above and towards 



