Haly Abbas calls it adresa, and says that it emits a fetid smell, and brings on inflammatory redness with an aqueous discharge from the wound. (Theor. viii, 21.) Avicenna calls it _kedusu duras_. (iv, 6, 3.) Isidorus says, “Chelydros serpens qui et chersydros dicitur quia et in terris et in aquis moratur.” (Origines.) Virgil translates Nicander’s account of this serpent into verses of inimitable spirit and elegance. It will be remarked by the curious reader that he mixes up together circumstances collected from Nicander’s separate descriptions of the chelydros and dryinus. (Georg, iii, 425.) Though critical emendation of the text of ancient authors be foreign to the design of this work, we cannot omit the present opportunity of stating that, from a comparison of the descriptions given by the Greek and Latin poets, we are inclined to think that the 434th line of Virgil should run thus: Sævit agris asperque siti atque exterritus œstro. This is founded upon the 417th line of Nicander’s Theriacs. It seems to be the chersydros which Dante alludes to in the following verses: “Come le rane innanzi alla nemica Biscia per l’acqua si dileguan tutte, Finch’ alla terra ciascuna s’ abbica.” _Inferno_, canto ix. For an account of the hydrus, see the sixteenth section. According to Sprengel, the dryinus is the _coluber lebetinus_. (Notæ in Dios.) Agricola finds fault with Lucan for distinguishing the chersydros from the hydrus or natrix. He remarks that the boa is a species of hydrus. (De Anim. sub.) They are now generally held to be different. See, however, our commentary on the sixteenth section. SECT. XV.—ON THE HÆMORRHUS, PRESTER, OR DIPSAS.