HETEROTOPIA, the development of tissues in sites other than those in which they are normally seen, is a phenomenon of great interest to pathologists and embryologists alike. It is, therefore, not surprising to find a fairly extensive literature on this subject which has been well reviewed in the account given by Willis.1 In the paper presented here, however, a case will be described which, to our knowledge, appears to be the only one of its kind; it will clearly have to be taken into account in any attempted explanation of the phenomenon of heterotopia in the intestinal tract. The report concerns the occurrence of gastric and of esophageal mucosa in the terminal ileum and past the ileocecal valve in unmistakably colonic mucosa. Report of a Case A 24-year-old white woman, gravida 1, para 0, admitted to the hospital in early labor with ruptured membranes, and leaking gross quantities of