chaptp:r IV. 



LOWER PTERYGOTA. 



{Wituilc.s.s In.sects — Bristle Tails and Spring Tails.) 



This group of insects includes those forms which are 

 primitively wingless, there being no trace of wing structure, 



Fig. is. — Lepisma doincstica: Adult female — enlarged. (After 

 Marlatt, Div. Ent., U. S. Dept. Ag.) 



(51) 



