52 LOWER PTERYGOTA 



and the evidence showing conchisively that unhke certain 

 wingless forms, which are related to winged species, these 

 have not had any winged ancestry. These species are 

 minnte, scaly, mouth parts fitted for biting. The develop- 

 ment is direct, the young hatching in the form of the adults 

 and developing by simple growth to the adult stage. 



¥10. 19. — Lepisnia saccharina: Adult — enlarged. (After Marlatt, 

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



Order THYSANURA. 



This group, the "bristle tails," includes the forms which 

 are provided with three bristles or bristle-like appendages 

 at the posterior end of the body. The antennae are long. 



