BOOK-LOUSE AND SILVER-FISH INSECT 313 



discrimination, was perceived to proceed from a small 

 work-box, comprising several compartments. Now, as 

 this very remarkable noise, which differs widely from 

 the tapping sound produced by Anobium tessellatum, is 

 supposed by many persons to be caused by some species 

 of spider, I resolved to investigate the phenomenon; 

 accordingly, having placed the work-box on several sheets 

 of writing-paper, I proceeded to open the compartments 

 in succession, examining each, with its contents, in a 

 good light, assisted by the employment of a large lens. 

 After having carefully inspected the compartment first 

 opened, a pause ensued, till the sound, which had been 

 interrupted, was renewed. Proceeding cautiously in the 

 manner described, the ticking sound was ultimately 

 traced to the last compartment, which served the pur- 

 pose of a pincushion, and was filled with bran. On the 

 cover being withdrawn, the bran was removed in very 

 minute quantities to a sheet of writing-paper, each 

 portion, when lightly spread by means of a feather, 

 being closely examined under the lens. The only occu- 

 pant of the box detected by this complete scrutiny was 

 a living Atropos pulsatoria ; and I think the facts of the 

 case fairly warrant the deduction that the ticking sound 

 was produced by it, more especially as no such sound 

 was ever after heard to emanate from the box. I may 

 add that the Atropos, which was placed in a clean phial, 

 died in the course of an hour, without emitting any 

 perceptible sound." 



The insect called A. pulsatoria in the above extract is 

 the same as what is now known as A. divinatoria, and 

 the evidence is obviously so strong in its favour that it is 

 only the very great mechanical and acoustical difficulties 

 involved that cause one to hesitate about accepting it. 

 To those, moreover, who have known these insects for 



