CHAPTER IV. 

 Order I. THYSANURA.* 



(Bristle-tails, Spring-tails, Fish-moths, et a/.) 



The members of this order are wingless insects which undergo no 

 metamorphosis, the larval form being retained by the adult. T/ie 

 mandibles and maxilUe are retracted within the cavity of the head, 

 so that only their apices arc visible; they have, however, some freedom 

 of motion, and can be used for biting and chewing soft substances. 

 True compound eyes are rarely present ; but in some genera there is a 



;p of agglomerated simple eyes on each side of the head. The 

 abdomen is sometimes furnished with rudimentary legs ; and in one 

 genus there arc well-developed abdominal legs. 



This order comprises chiefly minute insects, which live on decay- 

 ing vegetable matter, and can be found 

 abundantly in damp situations ; some 

 species, however, live in warm and dry 

 places, and feed upon starched clothing, 

 the binding of books, and other dry 

 substances. In the more common spe- 

 cies, the body is either elongated, and 

 furnished with six well-developed 1 

 and two or more long, many-jointed, 

 caudal appendages (Fig. 56) ; or short, 



FlC. *fo. 



: Lubbock.) 



FIG. 37. At// (After 



thick, and with a fork ng .ipp.ir.it UN bent under the 



abdoii of the thr< 57). 



* Thysanflra: thytanot (Oucmxof), a tassel; oura (ovpa). th< tail. 



