Sources : Centris

Lucan [1st century CE] (Pharsalia, Book 9, verse 790): And cenchris rose, straight gliding to his prey; / Spots paint his belly, countless, / more than those / Which tinge the Theban marble... - [Ridley, 1919 translation]

Isidore of Seville [7th century CE] (Etymologies, Book 12, 4:26): The cenchris is a snake that cannot bend so that it always makes a straight path. - [Barney, Lewis, et. al. translation]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Serpents 8.13): The cencris is an inflexible serpent, Isidore says, so it always makes a straight path. Whence Lucan: And the cencris will always slide straight to its prey. - [Badke translation/paraphrase]

Bartholomaeus Anglicus [13th century CE] (Liber de proprietatibus rerum, Book18.9): And hée sayth, that Cenchris is a Serpent, that bendeth not neither wiggeleth, but holdeth alway right foorth, as Lucanus sayeth. - [Batman]