ARTHROPODA. 



with sea7waterj a refuge from which I have turned' 

 it out in dozens. It has three setae ^ on the tail, and 

 two long antennae on the head, and these are, re- 

 spectively, nearly as long as the insect, so that it 



Fig. 57. — Lepisma 8aa<iha.Yifiaj enlarged. 



seems a most fragile creature to risk its long leaps. 

 The Thysanura are very simple forms; some have no 

 tracheae at all, and these, if present, are comparatively 

 little branched. They develop direct from the egg. 



The Orthoptera, which have two pairs of wings, 

 usually unequal, and biting jaws, undergo an incom- 

 plete metamorphosis ; they include Cockroaches, Ear- 

 wigs, Grasshoppers, Locusts, and Crickets. The Pray- 

 ing Mantis, so called from the way it folds its front legs 

 while watching its prey, and the Leaf Insect of the 

 East Indies, which lias wings exactly like green leaves, 

 — a case of "protective mimicry," — also belong to this 

 group. The young Cockroach has no wings ; ^ the 

 student should obtain specimens of the male and 

 female cockroach, and of the young, and note the dif- 



'■ Bristles. ^ Those of the female are rudimentary. 



