Sources : Cerastes

Aelianus [170-230 CE] (On the Characteristics of Animals, Book 1, 57): The cerastes is a small creature; it is a snake, and above its brow it has two horns, and these horns are like those of the snail, though unlike the snail's they are not soft. Now these snakes are the enemies of all other Libyans, but towards the Psylli, as they are called, they are gently disposed, for the Psylli are insensible to their bites and have no difficulty in curing those who have fallen victims to this venomous creature. Their method is this: if one of that tribe arrive, whether summoned or by chance, before the whole body is inflamed, and if he then rinse his mouth with water and wash the bitten man's hands and give him the water from both to drink, then the victim recovers and thereafter is free from all infection. And there is a story current among the Libyans that, if one of the Psylli suspects his wife and hates her on the ground that she has committed adultery; and if moreover he suspects that the child born from her is a bastard and no true member of his tribe, he then puts it to a very severe test: he fills a chest with Cerastae and drops the baby among them, just as a goldsmith places gold in the fire, and puts the infant to the proof by thus exposing him. And immediately the snakes surge up in anger and threaten the child with their native poison. But directly the infant touches them, they wilt, and then the Libyan knows that he is the father of no bastard but of one sprung of his own race. - [Scholfield translation]

Gaius Julius Solinus [3rd century CE] (De mirabilibus mundi / Polyhistor, Chapter 27.28): The cerastae carry four-fold little horns; they display them as bait, and destroy the birds they attract. They diligently hide the rest of their bodies in the sand, so that no sign of them is visible saving that part aforementioned. By this trick they ambush and kill birds, who have been lured by the hope of food. - [Arwen Apps translation, 2011]

Isidore of Seville [7th century CE] (Etymologies, Book 12, 4:18): The horned (cerastes) serpent is so called because it has horns on its head like a ram... It has four small horns, and it displays them as if they were food, so that it kills the animals roused by this enticement. It covers its entire body with sand, and reveals no sign of itself except that part by which it attacks the birds and animals that it has lured. And it is more flexible than other snakes, so that it seems to have no spine. - [Barney, Lewis, et. al. translation]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Serpents 8.9): Cerastes is a serpent, as Solinus says, having eight horns on its head like the horns of a ram. It hides its whole head in the sand, leaving only the horns outside. When sparrows or other birds flying by land on them to rest, this poisonous serpent snatches away those who have been killed by its poison. And this serpent is more flexible than other serpents, and this because it does not seem to have a spine by which it is held rigid. The horns sweat when they detect poison. From these horns are made the handles of knives which were placed at the tables of the emperors before all food, so that they would show by sweating if any food that had been served was contaminated with poison. - [Badke translation/paraphrase]

Bartholomaeus Anglicus [13th century CE] (Liber de proprietatibus rerum, Book18.31): Cerastes is an horned Serpent, as Isidore telleth li. 10. and hath hornes in either side of the head, crooked & wrinkled as the hornes of a Ramme: and he hydeth all his body in gravell and sand, and onelye leaveth his hornes uncovered: and foules sée them, and think that they be wormes, and lyght upon them, & intend to feede themselves therewith, and then the false and guylefull serpent, taketh sodainly the fowles ere they bee ware. Also this Serpent lyeth in a waight, in wayes and in privie places, and sueth both men and horses, that passe unwarely by the wayes, and slayeth them with privie biting. And the Glose super pen. cap. Gines. sayth, as it séemeth, that Cerostes is a manner kinde of Serpent, so malitious and venemous, that if onely his venime toucheth an horses hoose, it slayeth both horse and man. And therefore wher we have, Fiat Dan sicut Colubet in via, Cerastes in semita: ye other lether hath, Fiat sicut Coluber in via, & sicut Regulus in locato. Other men meane, that Cerastes is a manner Serpent, most venemous, and most malytious. Looke before in litera A. De Aspide, for there is mention made of Cerastes. - [Batman]