Sources : Ophites
Isidore of Seville [7th century CE] (Etymologies, Book 12, 4:30): The ophites is so named because it has the color of sand. - [Barney, Lewis, et. al. translation]
Bartholomaeus Anglicus [13th century CE] (Liber de proprietatibus rerum, Book18.9): Also Ophites is a Serpent painted with divers speckles, and hath as many manner of wise to noy and to gréene, as he hath diverse colours and distinct. Heereof speaketh Lucanus, & saith, that that manner of Serpent Ophites, hath as many manner of burnings and gréevings, as he hath speckles and coulours, & is painted with burning speckles. - [Batman]