Aetius (II. iii. 74) says that adhesion of the sclerotic to the lid may be separated by means of the pterygotome. Paul (VI. xxii) in empyema of the lachrymal sac dissects out the part between the sac and the canthus with the pterygotome, and again in excision of polypus aurium he says it may be employed. These uses of the pterygotome point to its having been a sharp-pointed knife of a small size. Albucasis, who conveys entire the passage on pterygium from Paul, gives figures of both these instruments. The pterygotome which Albucasis depicts is a small, narrow, sharp-pointed scalpel (Pl. IX, fig. 2). _Knife for plastic operation on the eyelid._ Greek, ἀναρραφικὸν σμιλίον. I have in describing the pterygotome given one instance of the use of the 'scalpel for the plastic operation', viz. to dissect away the base of a pterygium the rest of which had been separated off by means of sawing with a horsehair. The plastic operation for entropion seems to have been one which was very frequently required. We know that granular ophthalmia with trichiasis as a sequela was very rife. Aetius (quoting from Leonidas) and Paul give very nearly the same account of the operation to remedy the trichiasis. Paul says: 'Having placed the patient on a seat either before us or on the left hand, we turn the upper eyelid outwards, and if it has long hairs we take hold of them between the index finger and thumb of the left hand; but if they are very short we push a needle having a thread through the middle of the tarsus from within outwards. Then stretching the eyelid with the left hand by means of this thread, with the point of the scalpel held in the right hand, having everted the eyelid, behind the thread we make the inferior incision inside the hairs which irritate the eye, extending from the larger canthus to the smaller along the tarsus. After the inferior incision, having extracted the thread and having put a small compress under the thumb of the left hand, we stretch the eyelid upwards. Then arranging other small compresses on the canthi at their extremities we direct the assistant, who stands behind, to stretch the eyelid by means of them. Then by means of the 'scalpel for the plastic operation' (ἀναρραφικοῦ σμιλίου) we make the first incision called the 'arrow-shaped' a little above the hairs which are normal, extending from canthus to canthus and penetrating only the depth of the skin. Afterwards we make the incision called the crescent-shaped, beginning at the same place as the former and carrying it upwards to such a height as to enclose the whole superabundant skin and ending in like manner as it did. Thus the whole skin within the incision will have the shape of a myrtle leaf. Having perforated the angle of this portion with a hook we dissect away the whole skin. Then washing away the clots with a sponge we