There occurs in the salivary glands (1–5), buccal mucosa (6, 7), palate (8–11), cheeks and lips (12–15), antrum of Highmore (16–18), nares (19, 20), ethmoid sinuses (21), lacrimal glands (22), face (23–26), and elsewhere (27–41), a group of tumors about the origin of which an active controversy is still being maintained. These neoplasms are of composite structure, usually presenting epithelial elements in the form of cell strands, cell masses, alveolar arrangements, cartilage and pseudo-cartilage, myxomatous stroma, and cellular connective tissue. They have been grouped together as mixed tumors of the salivary glands. Those arising from other locations than the salivary glands are less complex in structure, and many of them fall into the group of cystic adenoid epithelioma (42, 43). Regarding the origin of mixed tumors of the salivary glands, Ewing has summarized the present status of our knowledge as follows: “1. The endothelial origin has been disproved. “2. No single source of the mixed tumors meets all the requirements. Some are distinctly adenomatous and probably arise from acini and ducts of the gland in which they are well incorporated. Others are encapsulated or extraglandular, and take the form of basal-cell or adenoid cystic epithelioma. These probably arise from misplaced and occasionally embryonic portions of gland tissue. Branchial remnants may possibly be connected with this group.