The other authors who recommend this unpleasant operation use mostly the polypus-scalpel or the phlebotome, and hence we may conjecture that a straight two-edged blade was considered the most suitable. The embryotome figured by Albucasis is of this shape (Pl. VIII, fig. 7), as is also the cutting part of the perforators of more modern times--fortunately now obsolete. _Probe pointed blade with two cutting edges._ There is in the Orfila Museum, Paris, a fine little two-edged bistoury of bronze with a probe point (Pl. VIII, fig. 2). It is a relic of the Roman occupation of Egypt. Its use must remain a matter of conjecture as we have no written description of such an instrument. It is perhaps a fistula knife. II A. (_a_) _Curved bistoury--'Crow Bill.'_ Greek, ὀξυκόρακον σμίλιον. In extirpating warts Paul (VI. lxxxvii) says we put them on the stretch with a vulsella and extirpate them radically with a scalpel shaped like a crow's beak or a phlebotome (ὀξυκοράκῳ σμιλίῳ ἢ φλεβοτόμῳ ἐκ ῥιζῶν ἐξελεῖν). This undoubtedly refers to a curved scalpel, for the grappling hook was called κόραξ. In Celsus the instrument appears under the term _corvus_. In describing the opening of the scrotal sac in the operation for the radical cure of hernia he says: Deinde eam ferramento, quod a similitudine corvum vocant, incidere sic ut intrare duo digiti, index et medius, possint (VII. xix). Vulpes (Tav. VII, 3 and 4) figures two curved bistouries from the Naples Museum. They have lost their tips. Both are of the same shape, but one has the blade slightly larger than the other. The handles are of bronze, the blades of steel. A good example is seen in the Athens scalpel box (Pl. IV). A powerful variety so strongly curved as to resemble a small billhook was found in the Roman hospital at Baden (Pl. IX, fig. 5). The handle is of ivory, the blade is of steel, and there is a mounting of bronze. _Pterygium Knife._ Greek, πτερυγοτόμος, ὁ; Latin, _scalpellus_. Paul (VI. xviii), quoting Aetius, II. iii. 60, says that there were two methods of curing pterygium. In the first the pterygium was raised by a small sharp hook, and a needle carrying a horsehair and a strong flaxen thread was passed under it. Tension being made on the thread by an assistant, the operator sawed off the pterygium towards the apex by means of the horsehair. The base of the pterygium was then severed with the scalpel for the plastic operation on entropion. The second method consisted in dissecting away the pterygium (stretched as aforesaid with a thread) with the instrument called the pterygotome (πτερυγοτόμῳ) care being taken not to injure the lids.