Fig. 5. The eyes of felids. The domestic cat (Felix sylvestris domestica; A,B) has a multifocal optical system (indicated by the ring-like structure in the photorefractive image) and a slit pupil. The Siberian tiger (Panthera tigris altaica; E,F) has a monofocal optical system (the photorefractive reflex has a smooth intensity gradient) and a circular pupil. The pupil appears slightly oval in both images because the tiger did not look at the camera. The photorefractive reflex is appearing sideways because the animal was lying on its side. The Eurasian lynx (Lynx lynx; C,D) has an eye of intermediate size and design. A faint ring-like structure is visible in the photorefractive image and the pupil is oval to rhomboid in shape. Scale bars are 5 mm.