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 /wr, and the tail 

 also thinly furred, while the common, or Nor- 

 way rat, is 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 inability 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 



I 



