Moynihan,1 in his monograph on retroperitoneal hernia, directs attention to the possibility of herniation of the small intestine into the lesser peritoneal cavity through an abnormal aperture in the transverse mesocolon. Four such hernias have been reported, one by Boettcher2 in 1878. In 1885, von Hacker3 suggested the advisability of performing a gastrojejunostomy by the posterior route, making the anastomosis in the posterior wall of the stomach through an opening in the transverse mesocolon. Thus, seven years before the retrocolic method of gastrojejunostomy was advocated, attention had been directed to the possibility of the small bowel herniating through an opening in the transverse mesocolon. This fact, evidently, was lost sight of, because it was only after fatalities from such hernias that surgeons began to suture the stomach or jejunum to the transverse mesocolon. Mayo-Robson,4 Moynihan,1 Mikulicz,5 and others have reported cases of this type.