(1) At ecdysis , the animal sheds the old exoskeleton while absorbing large quantities of water to stretch the new exoskeleton.(2) Upon ecdysis , a chitinous duplicature of the exoskeleton is shed and a growth band is added to the valves.(3) During terminal pleateau there are a series of large pulses of circulating ecdysteroids which appear to be necessary for successful ecdysis of the entire exoskeleton.(4) Considering Crustacea as an analogy, abnormal secretion of exuviation hormones in trilobite exoskeletons could also have caused irregular ecdysis and given rise to aberrant exoskeletal morphology.(5) In both groups, tissue loss must occur before a critical period to permit regeneration before the next ecdysis and proecdysial processes are suspended during regeneration in order to maintain proper timing of events.(6) Passonneau and Williams have described in the developing cecropia silkworm an ' ecdysial membrane' situated between pupal and adult cuticles.(7) The ecdysial suture is the region of the arthropod exoskeleton that splits to allow the animal to emerge during ecdysis.
