162 NEW YORK ZOOLOGICAL SOCIETY. 



dense pile or nap of hair-like barbule-tips, and this furry coat, 

 like the muffled oars of a boat, deadens all sound and renders the 

 flight of an owl almost noiseless, at least to our ears. 



About the eyes of an owl, two more or less circular feather disks 

 radiate outward, each composed of stiff loose feathers, whose de- 

 generate barbs and tarbules are often in the form of broad spatu- 

 late scales. These disks prevent the soft head plumage from 

 blowing into the eyes of the bird and also perhaps aid in directing 

 the scant light-rays of twilight, inward to the seat of vision. 

 This latter suggestion receives confirmation from the fact, that 

 in those species of diurnal habits, the disks are imperfectly 

 developed. 



Owls have large strong beaks and the upper mandible is always 

 prominently hooked, serving, as in the hawks, to tear the prey into 

 pieces when it is too large to be swallowed whole. Connected 

 w'ith this habit of swallowing the prey entire whenever possible, 

 owls, in common with many other birds, have the ability of being 

 able to disgorge inedible portions of the food. After a midnight 

 repast of mice, several oval pellets of fur and bones will be 

 regurgitated, the latter cleansed of every bit of flesh, and the 

 skulls of the rodents in as good condition as if prepared bv some 

 skilful osteologist. 



ADAPTATIONS OF SENSE ORGANS. 



From the outer contour of the feathers no hint is given of the 

 real size of the head and neck of an owl, and when we feel be- 

 neath the neck plumage, it is always a surprise to find how slender 

 this string of vertebrae and its scanty covering of flesh really is. 



The skull is large in comparison with the body, but the greater 

 part of the cranium is taken up by the eye-sockets. The remark- 

 able development of the sense of sight may be appreciated from the 

 fact that the cubic contents of each eye is slightly greater than 

 the capacity of the entire brain cavity, at least in the common 

 screech owl. This does not mean that the brain of an owl is 

 unusually small, but only emphasizes the great size of the eyes. 



The pupil is round and the iris is capable of remarkable volun- 

 tary contraction and accommodative expansion — the enlarged 

 pupil thus formed, admitting all the light rays which are available 

 in the dim twilight which characterizes even "darkest midnight." 

 There are few more beautiful sights than that seen through the 

 ophthalmoscope, looking into the eye of a great horned owl, and 

 it is well worthy of brief description. When the pencil of light 



