A gland that is located in the ocular region, nearer the inner canthi. Typically associated with or part of the nictitating membrane, when present.
Comment:
[taxon-note] "Rabbits, pigs and Mongolian gerbils have both a Harderian and a nictitans gland[ISBN:1118473523]"; [taxon-note] "the distinction between Harderian and nictitans gland is only valid in mammals - the medial ocular glands in other terapods are called Harderian glands regardless of their secretion[DOI:10.1007/978-3-642-76685-5_2]"