Benign tumors of the small intestine are among the rare causes of intestinal obstruction. When they produce obstruction, they almost always do so by acting as the starting point of an intussusception. Exceptionally, they may cause obstruction by actual obturation of the bowel. The following case history is one in which obturation was effected by a cyst of the terminal ileum, occluding the ileocecal valve. REPCRT OF CASES History. —F. P., a girl, aged 6 months, admitted, Sept. 15, 1923, had been delivered normally at full term. She had been bottle fed after the first two weeks, and had required frequent changes in the formula. Twenty-four hours before admission, she began to vomit, first bringing up curdled milk, and then clear fluid. She vomited eight times that day. The bowels did not move and enemas were ineffectual. When she was examined by rectum in the admitting room, a small greenish