VISUAL SYSTEM: STATE OF THE ART 



35 



Photo courtesy of Constance Warner 



Light-adapted eye of the smalltooth sawfish, Pristis pectinata (Latham)— Pristidae. 

 The upper margin of the iris is developed into a robust digitiform operculum pupillare 

 which descends during light adaptation as shown. Plate No. IIC 



Photo courtesy of Constance Warner 

 Light-adapted eye of the thorny skate, Raja radiata (Donovan)— Rajidae— showing the 

 well-developed operculum pupillare. The multiple fingers form a series of stenopaic aper- 

 tures during light adaptation, which provide nearly infinite depth of field combined with 

 ray selection. Plate No. IID 



