The diseased parts presented the following appearances. Portions of the acromion process, superior costa, and spine of the scapula, were of their natural appearance. But the coracoid process, the glenoid cavity, and the cervix, were entirely destroyed, and their situation occupied by an irregular broken-down tumour, consisting of osseous spiculæ, and cancelli, irregularly disposed, and forming cavities which were filled with blood, partly fluid and partly coagulated. The head of the humerus was extensively absorbed. The articulating cartilage was almost entirely destroyed, particularly on the inner side, where a large portion of the bony matter had also been removed. The ulcerated surfaces were of a dark, bloody colour. [HYDATIC TUMORS. Another disease of the bones which ought to be introduced here is the development of hydatids, which I described twelve years ago under the name of _osteo-hydatidic_ tumours. The seat of this affection is not confined to any particular class of bones; though the long are perhaps most prone to it. Its precise nature and origin have not yet been determined; nor are its symptoms such as to enable us, in the present state of our knowledge, to distinguish it from exostosis, osteosarcoma, and other maladies. Its progress is commonly slow, the surface of the tumour is smooth and regular, the skin exhibits no unusual appearance, and the adjacent textures rarely participate in the morbid action. The hydatids, usually of a globular figure, vary greatly in size and number, and are generally filled with a thin, limpid fluid. They appear to be of the nature of acephalocysts. The prognosis unfavourable, owing to the difficulty of destroying these parasites, and their constant tendency, when interfered with, to reappear. As soon as the true nature of this tumour is ascertained it should be laid freely open, its contents turned out, and the sac destroyed. For this purpose the sides of the cavity should be seared with the actual cautery, or touched with some of the more powerful escharotics, as the nitrate of silver, or the caustic potash. If these measures fail, and the disease involve the whole circumference of the bone, nothing short of amputation will suffice. This was successfully resorted to in one of the cases which came under the observation of Mr. Lucas of London.] TREATMENT OF TUMOURS.