RAPACIOUS BIRDS. 51 



sight, and is that which exists when the bird is 

 hovering on high.* 



The eyes of birds which fly abroad and seek 

 their prey by night, are so incapable of bearing the 

 light that they have only the full power of sight at 

 twilight, and the pupil is then so distended that it 

 admits an unusual proportion of the rays of light ; 

 a construction precisely similar to that which is 

 found among animals of the feline species. In 

 these, as well as among the other carnivora, the 

 pupil appears like a perpendicular line, by which 

 means the sight is more concentrated, and is 

 remarkably keen in moments of excitement, and 

 when the animal collects itself for the fatal spring 

 upon its prey. 



The feline races, having caught their prey, 

 teach their young to destroy it, to tear it, and to 

 revel in its blood ; and their type, the eagle, goes 

 one step farther, in teaching the power of flight. 

 Sir H. Davy had an opportunity of watching the 

 proceedings of eagles in this respect. He says, 

 " I once saw a very interesting sight above one of 

 the crags of Ben Nevis, as I was going, on the 20th 

 of August, in the pursuit of black game. Two 

 parent eagles were teaching their offspring, two 

 young birds, the manoeuvres of flight. They 



* See " Zoological Notes and Anecdotes," p. 277. 



E 2 



