The position of the patient, and the anæsthetic, are the same as in the previous operation. Reflected light may not be necessary. The ear and the surrounding parts are carefully cleansed and the head is shaved for a short distance over and beyond the mastoid process. A curved incision is made _close behind_ the auricle (Fig. 226), beginning at the upper level of its attachment and extending downwards along the retro-auricular fold. The incision goes down to the bone. The auricle is reflected forward and the soft tissues are separated from the bone until Henle’s spine and the posterior upper margin of the auditory canal are brought into view. Any bleeding, chiefly from branches of the posterior auricular artery, is at once arrested by pressure forceps, ligatures being afterwards applied. The assistant’s duty is to hold the auricle well forward and at the same time to keep the wound dry by swabbing. The fibrous portion of the canal is carefully separated from the bony portion with the periosteal elevator, the growth, if possible, being exposed without tearing through the thin layer of skin which covers it. The method of procedure now depends on the character and number of the exostoses present. (_a_) If situated superficially, they are removed by chiselling through their base with a gouge. They should be thoroughly removed, if necessary cutting through the normal bone well behind their base. (_b_) If deeply placed, they are more easily removed by first chiselling away a part of the upper posterior wall of the external meatus. This is done in the same manner as in the early stage of the complete mastoid operation (see p. 397). If possible the antrum should not be exposed, and care should be taken not to cut too deeply for fear of injuring the tympanic membrane. (_c_) If the exostoses spring from the anterior wall, it is necessary to make a T-shaped incision through the posterior membranous portion of the auditory canal in order to bring them into view clearly. This is done with a tenotomy knife, the flaps being held apart by means of forceps. The growths can now be removed by means of the gouge and mallet. (_d_) If the obstruction is due to multiple small exostoses forming an annular stricture within the bony canal, it is better to separate the membranous portion completely from the bony meatus. In doing so the skin over the exostoses tears through, so that the membranous portion can be reflected outwards as a finger-like process. To give greater room for the operation, the auricle and fibrous portion are pulled well forward by means of a loop of gauze passed through the lumen of the cartilaginous meatus.