CHAP. I. THEIR SENSES. 21" 



illuminated by a candle, or even by a bright 

 paraffin lamp, they were not usually affected 

 at first. Nor were they when the light was- 

 alternately admitted and shut off. Some- 

 times, however, they behaved very differ- 

 ently, for as soon as the light fell on them, 

 they withdrew into their burrows with 

 almost instantaneous rapidity. This occurred 

 perhaps once out of a dozen times. When 

 they did not withdraw instantly, they often 

 raised the anterior tapering ends of their 

 bodies from the ground, as if their attention- 

 was aroused or as if surprise was felt ; or 

 they moved their bodies from side to side as- 

 if feeling for some object. They appeared 

 distressed by the light ; but I doubt whether 

 this was really the case, for on two occasions 

 after withdrawing slowly, they remained for 

 a long time with their anterior extremities 

 protruding a little from the mouths of their 

 burrows, in which position they were ready 

 for instant and complete withdrawal. 



"When the light from a candle was con- 

 centrated by means of a large lens on the 

 anterior extremity, they generally withdrew 

 instantly ; but this concentrated light failed 



