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Fig. 7. Multifocal optical systems and slit pupils in large-eyed terrestrial
vertebrates. Clearly visible ring-like structures were observed in
photorefractive images of the eyes of domestic sheeps (Ovis aries
domesticus; A) which have horizontal slit pupils (B). Similar pupil
shapes were found in other artiodactyls, such as the reindeer (Rangifer
tarandus; C). The Nile crocodile (Crocodylus niloticus; D) has a
vertical slit pupil in combination with a multifocal optical system. Scale
bars are 10 mm.