Contributions to the comparative anatomy of the mammalian eye, chiefly based on ophthalmoscopic examination

There is absolutely nothing to be seen in the fundus of the rhinoceros but a large circular white disc in the centre of a violet-brown field covered with a faint network of coarse stippling. Rhinos have bright twinkling eyes. This ?twinkle' is due to a rapid oblique movement of the eye outward and slightly upwards, a movement which the animal performs every few seconds. This movement may be for the purpose of protection, to enable them to look around without the trouble of turning their large, massive heads. It also seems in some measure to replace our ?winking'. The eye is placed so as to have an uninterrupted view forwards and laterally. The skin round the eye forms large irregular folds, the outermost being about 5 inches across. The two lower folds form a right angle, while the upper fold forms a portion of a circle. Pupil is round, 9 mm in diameter, surrounded by a dark brown iris. The cornea is formed of two intersecting arcs nearly corresponding to the angles at the canthi. Well-formed nictitans is present. The fundus of Rhinoceros unicornis is very primitive.