161 



turned backward. On the fifth segment below there is a 

 simple unpaired grasping foot which is capable of being 

 protruded forward and downward; at its tip there are 

 t\vo triangular, sharp, flat, chitinous hooks, and below 

 them some stiff bristles. The booklets serve as aids in 

 boring in the sand and to fix themselves; the organ 011 

 the fifth segment assists the larva in seizing and holding 

 its prey, and also in constructing the pitfalls. 



21 



Fig. 54. Leptidse. 18. Arthroceras (type) , wing; 19, Arthrocei as 

 (type 1 ), antenna; 20, Rhachicerns, head; 21, Athcri.v, venation. 



