From Oribasius (_Med. Coll._ VII. xvi) we learn that sometimes the lips were flat (ἐπίπεδα τὰ χείλεα) and sometimes concave (σεσιμωμένα τὰ χείλεα). This does not, however, mean that the border was guttered, but that the whole lip instead of lying in one plane was arched. From a passage in Aretaeus we learn that one reason for the cup being bellied out above was that there was oil floating free in the instrument, which might otherwise escape and scald the patient. Aretaeus says: 'Apply plenty of heat so as to warm the part as well as attract. The cup should be light earthenware (κεραμεοῦν κοῦφον) and adapted to the side (ἁρμόζον τῇ πλευρᾷ), or bronze with flat lips (πρηνῆ τὰ χείλεα) so as to comprehend the parts affected with pain, and we are able to place inside it much fire with oil, so that it may keep alive for a considerable time. We must not apply the lips closely to the skin, but allow access to the air so that the fire may not be extinguished' (_De Morb. Acut._ i. 10). Antyllus says there are three materials of which cups are made, glass, horn, and bronze. He rejects the silver ones because they heat too readily. The bronze are the ones most commonly used. Glass is used where we wish to mark the quantity of blood extracted. Horn ones are useful about the head, where bronze ones would be difficult to remove, and also in the case of nervous persons who dread the flame. Bronze and glass cups may be used without flame like horn ones if a hole is bored in the summit and the air sucked out, and the finger or a piece of wax is applied immediately (Oribasius, _Collect._ VII. xvi). Aristotle in his _Poetics_ discusses various tricks and arts of authors and among these he mentions the riddle of which he gives as an example: ἄνδρ' εἶδον πυρὶ χαλκὸν ἐπ' ἀνέρι κολλήσαντα 'I saw a man who had glued on a man bronze by means of fire' the reference being to a bronze cupping-vessel (see also Mayor's note to Juvenal xiv. 58). The cups mentioned by Hippocrates are also of bronze. The earliest written references are thus to bronze cups worked by fire. Ethnological research would indicate, however, that horns worked by suction represent the more primitive form. A good number of cups have come down to us. There are fourteen in the Naples Museum. There are two prevalent or usual types, one conical, and the other flatter and more rounded. The largest cup known is in the Athens Museum. Attached to it had been a chain 20 cm. long to hang it up by. It is 16 cm. in height, and was found in a tomb at Tanagra. This cup with its chain and attachment is shown in Pl. XXXIII. In the British Museum there is one of bronze, 4 inches high and of the elongated conical shape. It was found in Corfu (Pl. XXXIV). One in Naples of similar shape has a ring attached to its summit as the Athens specimen had (Pl. XXXV).