344 JAMES ROLLIN SLONAKER 
above the general surface. Cuvier (1817) says a large tympanum 
is present. The reason for theabsence of the aural appendage 
is apparent. It could be of no assistance in hearing and would 
be a hindrance to the progress of the animal through the soil. 
According to Allen (12), the sense of smell is not very keen. 
He bases this conclusion on the behavior of a mole which he 
observed in captivity. He noticed that it did not take the 
worms offered until the nose was almost, if not completely, in 
contact with them. The tactile hairs of the snout were appar- 
ently of greater use in securing the food than the sense of smell, 
for they were evidently stimulated. 
Since the mole lives its whole life in darkness, a marked de- 
generation of the eye has resulted. In the adult Scalops this 
degeneration has gone so far that it can at best only distinguish 
between light and darkness, and it is extremely doubtful whether 
the eye functions at all. It is attached to the under surface 
of the skin a little posterior to the angle of the mouth (Herrick, 
792). An eye socket has wholly disappeared. 
The size of the eye has been greatly reduced, but is visible 
as a small dark area lying under the skin when the fur is parted 
over this region. The fusion of the lids has reduced the eye- 
cleft to a microscopical tube which meets the eyeball at such an 
angle that rays of light could not enter the eye along the axis of 
vision. All the elements of the mammalian eye are present, 
but they are in such a crowded condition, due to the great reduc- 
tion in size of the eyeball, that it would be impossible for them 
to function in a normal manner (Slonaker, ’02). 
Sweet (’09) has studied the eyes of Chrysochloris hotten- 
tota and C. asiatica and compared them with Talpa and Scalops, 
and concludes that they are more degenerate than in the latter 
and are practically incapable of distinguishing light and darkness. 
To compensate for the loss of information from the sense of 
sight, the sense of touch has been developed to a remarkable 
degree. These tactile organs are located principally on the snout 
and on the hands and consist of certain hairs and end-organs 
which are richly supplied with nerve fibers. 
