88 Life and Immortality. 



when the creature opens its mouth. In length the mandible 

 is three times its breadth, and furnished with three sharp 

 teeth on the outer edge, and with a broad cutting margin 

 within, and still further inwards with a number of straggling 

 small spines. The lower lip is broad and stout, with a dis- 

 tinct medium suture, which indicates a former separation in 

 embryonic life into a pair of appendages. Its palpi are three- 

 jointed, the joints being broad, and directed backwards in 

 life, and not forwards, as in the higher insecta. 



LEPISMAS AT WORK. 

 How Books are Destroyed. 



Perhaps not more than a half-dozen species of Lepisma are 

 known to exist in this country. Our commonest form is 

 very abundant in the Middle States under stones and leaves 

 in forests, and northward in damp houses, where it has much 

 of the habits of the cockroach, eating clothes, tapestry, silken 

 trimmings of furniture, and doing great mischief to libraries 

 by devouring the paste and mutilating the leaves and covers 

 of books. Our heat-loving form, which is apparently allied 

 to the Lepisma thermophila of Europe, and which may be 

 an imported species, is quite as destructive as its nearest of 

 kin Lepisma saccharina. It does not confine its ravages to 



