670 



THE EYE IN EVOLUTION 



Figs. 798 to 803. — The Unioculab Fields of Vertebrates. 



Fig. 798. — A teleostean fish. 

 IIO° 



Fig. 799. — The chameleon. 

 IbO" 



Fig. 800.— An owl. 



200 



Fig. 801. — A primato. 

 215° 



Fig. 802.— The cat. Fig. 803.— The horse. 



Horizontal meridian. N, nasal ; T, temporal. 



however, occur ; thus the wide visual field of the horse in the obliquely 

 horizontal meridian (215° to 228°) is largely due to the marked forward 

 prolongation of the retina on the nasal side, while the relatively small 

 field of many birds (the owl, 110°) and also of some deep-sea fish is a 

 consequence of the small extension of the retina in their tubular eyes 

 (Figs. 798 to 803). 



