138 THE MAMMOTH CAVE. 
are some small water insects also, which I sup- 
pose are crustacean. Unfortunately, three vials, 
containing numerous specimens of these insects, 
were lost with my valise from the stage-coach, 
and I fear will not be recovered. 
“The only mammal, except the bats, observed 
in the Cave, is a rat, which is very abundant, 
judging from the tracks which they make, but 
so shy and secluded in their habits that they are 
seldom seen. We caught two of them, and, for- 
tunately, they were male and female. 
“The chief points of difference from the com- 
mon rat, in external characters, are in the color, 
which is bluish, the feet and belly and throat 
white, the coat, which is of soft fur, and the tail 
also thinly furred, while the common, or Nor- 
way rat, 1s gray or brown, and covered with 
rough hair. The Cave rat is possessed of dark, 
black eyes, of the size of a rabbit’s eye, and en- 
tirely without iris; the feelers, also, are uncom- 
monly long. We have satisfied ourselves that 
he is entirely blind when first caught, although 
his eyes are so large and lustrous.” 
We interrupt Professor Silliman here to sug- 
gest that the ability of the rat to see was per- 
haps owing to the unaccustomed, blinding light by 
which it was examined. It will be seen that the 
