702 THE EYE IN EVOLUTION 



jaculator, has frequently been quoted to illustrate how highly developed 

 the judgment of distances may be in a fish ; while swimming it will 

 spit a jet of water at an insect flying three feet above the surface 

 with an astonishing accuracy, overwhelming it in the air and devouring 

 it when it has been brought down to the surface of the water. An 

 animal, particularly one not provided with a fovea, which can overcome 

 the visual disabilities of localization in air while immersed in water ^ 



Fig. 847. — The Spatial Orientation of Fishes. 



Resting trout lying in the Brule River, Minnesota. Note their arrange- 

 ment in regular and disciplined ranks (Gudger ; from Thorpe's Learning and 

 Instinct in Animals, Methuen and Co.). 



and can still so deftly impale a flying insect must have an unusually 

 excellent judgment of distances. 



Similarly in amphibians and reptiles, the accuracy of the insect- 

 catching activities of the frog, the toad or the lizard betoken well- 

 developed spatial judgments ; but in some birds this faculty 

 appears to be even of a higher standard. This particularly applies 

 to birds of prey, which swoop down on their quarry with unerring 

 accuracy from astonishing heights, a feat doubtless rendered possible 

 by the bi-temporal fovese. The accuracy of the hawk, provided with 

 two temporal foveae, in swooping on its prey upon the ground at great 

 speed and with great precision is in strong contrast to the conduct of 



1 p. 672. 



