Of non-malignant tracheal tumors observed by others, the large majority were papillomata; next in number come fibromata. Aside from these two kinds of tracheal tumor, the cases recorded in literature are the following: Rokitansky more than thirty years ago described tracheal enchondromata found after death; and Cohen discovered in the corpse of a phthisical patient a number of small enchondromata on the central portions of the tracheal cartilages. Steudener, Demme, Wilks, Chiara, and Eppinger have observed, post-mortem, tracheal osteomata. Gibbs has described a tracheal cystic tumor[2] seen with the laryngoscope; Müller, under the guidance of Gerhardt, a myxo-adenoma observed tracheoscopically and carefully studied {141} during life and after death; and Eppinger has recorded a case of post-mortem tracheal adenomata and cysts, Simon having previously found three similar tumors on dissecting a new-born tigress. Virchow speaks of the occurrence of retro-tracheal retention-cysts, and Gruber has observed several; but there can be no doubt that at least some of the tumors thus described are nothing but circumscribed dilatations of the tracheal mucous membrane--practically, dilated mucous glands. As to malignant tumors, in addition to my two cases Schrötter has reported two cases of sarcoma, and Labus one of fibro-sarcoma, while Rokitansky, Klebs, Koch, Schrötter, Langhans, and Mackenzie have described cases of carcinoma. [Footnote 2: Cohen questions whether this was a cyst or an abscess. It burst spontaneously.] Cases of cancer of the oesophagus, which involve the trachea--excluded, as before stated, from present consideration--are, comparatively speaking, by no means rare, and are apt to establish a fistulous communication between the two tubes.