GOLDEN EAGLE. 15 



was instantly pursued by the Eagle (which must have 

 been on a neighbouring rock unperceived) across the glen, 

 the breadth of which was at least two miles. The Eagle 

 made several pounces in view, without success; but as 

 there was no wood nor cover on the opposite mountain 

 sufficient to conceal so large a bird as a Black Grouse, he 

 doubtless forfeited his life to the merciless tyrant of the 

 rocks." 



Dr. Fleming, who had opportunities of observing these 

 birds when residing in Zetland, says that they are general 

 depredators, and in the breeding-season rob the rock birds 

 of their young, especially the Gulls and Cormorants. This 

 habit is probably common to both species of British Eagles. 



The power of vision in birds is observed to be very ex- 

 traordinary ; and in none is it more conspicuous than in 

 the Eagles, and the Falconida generally. It has been 

 stated that probably in the whole range of anatomical 

 structure, no more perfect or more conclusive proofs of 

 design could be adduced than are to be found in the nu- 

 merous and beautiful modifications in the form of various 

 parts of the eyes of different animals, destined to exercise 

 vision in media of various degrees of transparency as well 

 as density. The figure on the right hand of the vignette 

 at the end of this article represents the circle, composed 

 of fifteen bony plates, by which the orb of the eye of the 

 Golden Eagle is supported. These bony plates are ca- 

 pable of slight motion upon each other. The figure on 

 the left hand in the vignette represents the crystalline lens 

 of the same bird ; the lens being subject to great variety 

 of form in different birds. In the Eagle, the proportion 

 of the axis to the diameter of the lens is as three and 

 eight-tenths to five and seven-tenths ; in the Great Owl, 

 which seeks its prey at twilight, the relative proportions of 



