Lucan [1st century CE] (Pharsalia, Book 9, verse 800): ...pareas, head erect / Furrows with tail alone his sandy path... - [Ridley, 1919 translation]

Isidore of Seville [7th century CE] (Etymologies, Book 12, 4:37): The parias is a snake that always travels on its tail, and appears to make a furrow. Again, Lucan said this concerning it [Civil War 9.721]: Whence the parias is pleased to plow a path with its tail.. - [Barney, Lewis, et. al. translation]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Serpents 8.27): Pharias is a serpent, as Isidore says, which always seems to be walking on its tail and making a furrow. Whence Lucan: The pharias is content to furrow a path with its tail. - [Badke translation/paraphrase]

Albertus Magnus [ca. 1200-1280 CE] (De animalibus, Book 25, 44): Phareas is a snake which moves forward almost wholly erect, gliding along on its tail and that portion of its body next to the tail. Therefore, it seems to leave a furrow in its wake, wherever it travels. Whence the verse by Lucan: "Where its path extends, the phareas furrows with its tail." - [Scanlan]