NO. lO KKKUING OKCiANS OK A RA( H N IDA SN(Jl)( .l< ASS X5 



tubes give attachment to retractor muscles of the chcHcerac. These 

 facts would suggest that the spiracular tubes are elongate atrial 

 chambers, or secondary invaginations of the integument, rather than 

 true tracheal trunks. From the lower end of each tube a large tracheal 

 tnmk (Tra) arises laterally, turns posteriorly, anrl gives od bundles 

 of finer tracheae that aerate the entire body. 



