Anal valve
The remnants of the sclerite of the 11th abdominal segment in insects are called anal or anus valves . These are the dorsally lying, unpaired epiprocts and the paired paraprocts lying laterally below . In most insects, these clasp-like surround the anus and the end ring ( periproct ).
The three sclerites assume a special function in the larvae of the dragonfly (Zygoptera). Here all three sclerites are extended to leaf-shaped tracheal gills and are used for breathing in the water.