3 i6 



NORMAN E. M INDOO. 



LIGHT EXPERIMENTS FOR TROGLOHYPHANTES CAVERNICOLA KEY. 



[ ? Abdomen was lost. ] 



external eyes. Sometimes the eyes are not in their natural 

 position. Often black pigment specks are found where the eyes 

 are absent. The largest eyes are two fifty-fifths millimeter 

 (0.036 mm.) in diameter, being twice as large as those of the newly 

 hatched, but such individuals are comparatively rare. Hence 

 as a rule, the eyes do not grow larger after birth, while the speci- 

 mens more than thribble themselves in size. Neither locality 

 nor size of the specimen determines the degree of degeneration 

 in the eyes, or the shade of coloration. Generally, the lighter 

 colored the individual, the more degenerated the eyes, and vice 

 versa. Specimens totally devoid of eyes always stay in the dark 

 more than fifty per cent, of the time; those with one or more 



