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provoked it snaps at the object. During the daylight it sits quietly in a 
nest it has formed for itself of cotton batting, which it pulled into a 
fluffy mass. At night it is frequently moving about in its cage. Turning 
on an electric light near its face always produces a twitching of the eye- 
lids; so there can be no doubt that the light is perceived. An object held 
some distance from the cage either on one side or another is always per- 
ceived, but just how precise its vision is has not been determined. Its 
hearing is acute. 
Tue Eye. By J. R. SLonaker. 
As far as I have been able to ascertain, little or no microscopical 
investigation has been made on the eye of the Mammoth Cave rat. 
A glance at a photograph of a cave rat (Fig. 1) shows that the eye is 
as prominent as in the common gray rat (Wig. 2). 
Fig.3. Mammoth Cave Rat (x 8). 
If the elements of the retina have the same function in the cave rat 
as in other rats, we may approach closely to their power of sight under 
favorable conditions, by comparing their retina with that of those living 
in the light. For such a preliminary comparison I have chosen the nearest 
allied form which I could readily get, the common gray rat (Mus de- 
cumanus). 
