PLATE 26 (Continued).

Fig. 5. Chronic Suppurative Otitis Media; Caries and Necrosis of the Mastoid Process; Perforation of the Sigmoid Groove; Purulent Thrombosis of the Transverse Sinus (Pyemia) (P.).-Right temporal bone from a girl thirteen years of age, seen from behind after removal of the dura mater. Owing to the carious destruction within the mastoid process, the antrum is greatly enlarged, the wall of the transverse sinus in contact with the cavity presents a perforation (1) 4 mm. in height immediately below the upper border of the pyramid (2). The bone in the immediate vicinity is soft and brittle (3). The adjacent sinus is filled with a purulent thrombus. The tip of the petrous portion has been removed (4).

Fig. 6. Acute Suppurative Otitis Media (Diphtheria); Caries of the Mastoid Process; Purulent Thrombosis of the Transverse Sinus and the Mastoid Emissary (Pyemia) (B.).-Left temporal bone from a child two years of age. Seen from behind after removal of the dura mater. The bony wall of the sigmoid groove is covered with a delicate deposit. The bone about the middle of the groove (2) is carious. The mastoid foramen (3) is enlarged; the adjoining wall of the sinus (4) is discolored, thickened, and covered with granulations. The mastoid emissary, which empties at this point, is thrombosed (5). At the corresponding point on the inner wall of the sinus (6) there is a purulent thrombus (7) completely obstructing the sinus, while above and below are additional parietal thrombi (8).