Definition:
"Four processes (canals) of the excretory canal cell each contain a central collecting lumen which feeds to a central lumenal canal in the cell body; the central canal forms a specialized membrane to release fluids into the excretory duct. These five canals form a continuous H-shaped channel which extends almost the full length of the body, generally in contact with the lateral hypodermis and the pseudocoelom." [
WBPaper:00038216]