GOLDEN EAGLE. 15 
was instantly pursued by the Hagle (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 Hagles. 
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 Falconide 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 
