SUPERIMPOSED parallel slits between bands of the internal oblique and transversus abdominis muscles occasionally open to allow formation of a hernia at the level of the semicircular line of Douglas, which enters a shallow subaponeurotic space lateral to the rectus sheath and deep to the aponeurosis of the external oblique. Zimmerman et al1noted this and described its anatomical peculiarities. Four cases, with incarceration and strangulation, show this hernia to be dangerous and misleading. Report of Cases Case 1. —A 23-year-old man, loading heavy oil drums, suddenly noticed tender, firm swelling in the left lower abdominal wall. Sharp pain rendered him helpless, and after some delay he was brought to the hospital with an oblique, oval, exquisitely tender mass, midway between the umbilicus and anterior superior iliac spine (Fig 1). During examination it quickly disappeared, with immediate cessation of pain. Because considerable time had lapsed, exploration was advised. Upon