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 Larbules 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 
with 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 by 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 vertebrze 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 
